Monday 9:00-12:40
Deborah Roach
Title: Welcome
Affiliation: University of Virginia
Anni Hämäläinen
Title: Fitness consequences of peak reproductive effort
Authors: AG McAdam, B Dantzer, JE Lane, S Boutin et al.
Affiliation: University of Alberta, Canada
Abstract: Breeding success of iteroparous species is often age-specific, showing improvement from onset of breeding until a peak in prime age, and a subsequent senescent decline. Despite its potential influence on fitness outcomes, the role of peak reproduction (i.e. maximum reproductive effort) has been largely overlooked in studies of life history evolution. We show that fluctuating resource availability leads to selection for reproductive flexibility and timing of peak reproductive effort to high anticipated fitness payoffs in red squirrels. Adjustments in peak reproductive effort significantly influence lifetime fitness, representing an important but overlooked component of the life history phenotype of iteroparous organisms.
Natalie Kerr
Title: Age-specific demography and lifetime reproductive success of native and exotic Pieris butterflies.”
Authors: Natalie Kerr, Elizabeth Crone, and Francie Chew.
Affiliation: Tufts University, Medford, MA.
Abstract: As individuals age through time, we often detect changes in life history processes, such as survival and reproduction. Collectively, these age-dependent processes govern the structure and dynamics of populations. Over the last century, we have seen a simultaneous decline of the native mustard white butterfly, Pieris oleracea, along with the introduction, spread, and proliferation of the introduced cabbage white butterfly, Pieris rapae. Here, we estimated survival and fecundity of both these Pieris species to delineate any differences in age-dependent vital rates. We found that the cabbage white has greater adult survival and fecundity only until around age 10 in days, then the native mustard white has greater survival and fecundity. Over their expected lifetime, we found that on average a female cabbage white contributes three times as more female eggs to the next generation than a female mustard white
Maya Groner
Title: Influence of life history plasticity on disease
Authors: Maya Groner, John Hoenig and Jeff Shields
Affiliation: Virginia Institute for Marine Science
Abstract: Diseases, particularly high-impact emerging diseases, place an enormous amount of selection pressure on host populations. The environmental factors that facilitate disease emergence are often associated with critical life history transitions which themselves may alter epidemiological processes (ie, transmission, susceptibility, and survival). For example, in the American lobster, increased temperatures are associated with molting, a key defense against epizootic shell disease (ESD). In the absence of molting, increased temperatures are also associated with increased disease incidence and severity. I am interested in how temperature-induced plasticity in molting may constrain or facilitate adaptation of lobsters to a novel disease stressor.
Aldo Compagnoni
Title: Climatic variability and population dynamics
Authors: Aldo Compagnoni, Andrew Bibian, and Tom Miller
Affiliation: Rice University
Abstract: Ecological theory emphasizes that climatic variability should decrease long-term stochastic population growth rate. However, climatic variability can in principle have neutral or positive effects as well. The effect of climatic variability depends on the relationship between climate factors and population growth rate. Concave, linear, and convex relationships have, respectively, negative, neutral, and positive long-term effects. We addressed how frequent these types of relationships are by compiling Long Term Ecological Research network data. Among the ~500 species we analyzed, 55% of relationships were linear or convex. Thus, our results question the emphasis of theory on the negative effects of environmental variability.
Daniel Harris
Title: Peruvian Genome Project: A study in Pre and Post Peruvian Inca Demography and their Evolutionary Dynamics
Authors: Daniel Harris1,2,3, Wei Song1,2,3, Amol Shetty1,2, Omar Cáceres4, Carlos Padilla4, Kelly Levano4, Víctor Borda5,6, Pedro Flores-Villanueva4, Omar Trujillo7, Cesar Sanchez4, David Tarazona4, Eduardo Tarazona5,6,Timothy D. O’Connor1,2,3, Heinner Guio4
Affiliations: 1Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD; 2Department of Medicine, University of Maryland School of Medicine, Baltimore, MD; 3Program in Personalized and Genomic Medicine, University of Maryland School of Medicine, Baltimore, MD; 4Laboratorio de Biología Molecular, Instituto Nacional de Salud, Lima, Perú; 5Departamento de Biologia Geral, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil; 6Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil; 7Centro Nacional de Salud Intercultural, Instituto Nacional de Salud, Lima, Perú
Abstract: We sequenced 150 and genotyped 130 Native American and Hispanic individuals from Peru to improve the understanding of Peruvian demography. All pairs of populations diverged approximately 10,000 years ago, which is in accordance with the hypothesis of rapid peopling of the Americas after the Last Glacial Maximum. We further constructed migration and diversity topography models of Peru which detected a migration corridor connecting the city centers in the Andes, Amazon, and Coast as well as showing the Andes as a barrier to gene flow. IBD networks showed the majority of migration to be from the Andes to the other regions.
Spencer Ingley
Title: Life-history evolution across stages of divergence
Authors: Spencer J. Ingley and Jerald B. Johnson
Affiliation: University of North Carolina, Chapel Hill
Abstract: How selection acts to drive trait evolution at different stages of divergence is of fundamental importance in our understanding of the origins of biodiversity. Yet, most studies have focused on a single point along an evolutionary trajectory. Here, we provide a case study evaluating the strength of divergent selection acting on life-history traits at early-versus-late stages of divergence in Brachyrhaphis fishes. We find that the difference in selection is stronger in the early-diverged population than the late-diverged population, and that trait differences acquired early are maintained over time.
Kevin Healy
Title: Mapping animal life-history strategies using the COMADRE database
Authors: Healy, K., Salguero-Gómez, R., Buckley, Y.M.
Affiliations: Trinity College, Dublin
Abstract: Understanding the patterns of life-history strategies is a central goal in comparative biology. While it is clear that trade-offs and constraints shape what life-history strategies are possible, the pattern of strategies across animals is still unclear. Using demographic data for a phylogenetically diverse range of species from the COMADRE database we test whether life-history traits follow expected patterns relating to body size constraints and expected trade-offs between reproduction and maintenance. We find that life-history traits scale with body size as predicted by metabolic theory and that the relationship between life history strategies is more complex than a singular fast-slow continuum.
Emily Schultz
Title: The importance of within-patch heterogeneity for metapopulation dynamics: applying scale transition theory to a size-structured metapopulation model
Authors: Emily Shultz and Tom EX Miller
Affiliation: Rice University
Abstract: When accounting for local environmental effects on larger-scale population dynamics, using average values is problematic if there are non-linear dynamics. Here we apply scale transition theory to scale from local to metapopulation dynamics, using a simulated population. We simulated a demographic dataset with non-linear relationships between an environmental variable and vital rates. We used Bayesian models to parameterize vital rate functions, including a non-linear term for environment. We then built two integral projection models: a mean field model and a scale transition model. The addition of the scale transition term resulted in a more accurate estimate of the population dynamics.
Jennifer Blake-Mahmud
Title: Changes in sex expression correlate with health in striped maple, Acer pensylvanicum (Sapindaceae)
Affiliation: Rutgers University
Abstract: In plants sex is usually a fixed trait, however, in rare species, a plant may change sex during its lifetime. One such species is striped maple, in which individuals can change sex repeatedly. Amongst five New Jersey populations, 30% of trees switched sex expression between 2014 and 2016. Preliminary data suggest that size, injury, and carbohydrate reserves may impact the frequency and direction of sex change. The switch from male to female correlates with increased carbohydrates the winter prior to flowering and with decreased health. The final floral sex is determined as late as three weeks prior to flowering.
Robert Shriver
Title: Bridging the gap between physiology and demography to understand climate change responses of a desert annual plant community
Affiliation: Duke University
Abstract: Tradeoffs have long been an essential part of the canon explaining high species diversity. Yet there has been a scarcity of linked demographic and physiological evidence to support the role of resource use tradeoffs in natural systems. Using Chihuahuan desert annual plants, I show that demographic tradeoffs driven by soil moisture variation allow multiple species to partition a limiting resource. Specifically, by achieving highest fitness in either rainfall pulse or interpulse periods, species exploit temporal niche differences that could allow coexistence on a shared resource. Differences in fitness are explained in part by response of photosynthesis to changing soil moisture.
Will Petry
Title: Partitioning the linear and non-linear effects of climate change on two-sex population dynamics
Authors: William K. Petry1,4, Tom E.X. Miller2, Judy D. Soule4, Kailen A. Mooney3,4
Affiliations: 1Institute of Integrative Biology, ETH Zürich, Switzerland; 2Department of BioSciences, Program in Ecology & Evolutionary Biology, Rice University, Houston, Texas, USA; 3Department of Ecology & Evolutionary Biology, University of California, Irvine, California USA; 4Rocky Mountain Biological Laboratory, Gothic, Colorado, USA.
Abstract: Males and females may have sex-specific responses to environmental change. Responses of either sex may directly affect population dynamics, but may also bias operational sex ratios (OSRs) and limit reproduction. We partitioned the demographic effects of climate change on a long-lived dioecious herb using a two-sex demographic model, parameterized with contemporary and historic data. Changing aridity over the species elevation range and over the past 40 years had sex-specific effects on vital rates, sufficient to explain observed skews in OSR and strongly limit mating. Population growth rates were robust to OSR changes; however, the loss of propagules may dampen range expansion as climate change continues.
Monday 1:40-5:00
Emily Bruns
Title: Demography of disease in natural plant populations: host lifespan and the evolution of resistance
Affiliation: University of Virginia
Abstract: Disease can strongly impact the ecology and evolution of natural populations by reducing population growth rate and generating selection for disease-resistance traits. Demographic studies offer a window into both these processes: We have been using a long-term demographic study of a vector-transmitted sterilizing disease in a long-lived population of wild carnations to understand how host life history traits influence host resistance and transmission of a vector-transmitted sterilizing disease in a long-lived population of wild carnations. Through this work we have found that longer-lived hosts can evolve resistance more rapidly than shorter-lived hosts, and are less likely to maintain resistance polymorphisms. We have also found that resistance increases with age, and that this age-specific resistance has important consequences for transmission dynamics.
Robert Richardson
Title: Probabilistic Integral Population Models
Authors: Robert Richardson and Mark Belk
Affiliation: Brigham Young University
Abstract: A hierarchical Bayesian model using a Poisson process likelihood and an integral population model framework can be a flexible approach to modeling demographics over time. We show how the long-term growth rate, sensitivity, and elasticity can be calculated using this approach and compare the results with estimates from matrix population models. Through simulation studies, we show how the parameters of the growth, survival, and other functions in the integral population model can be estimated with only the time profiles, potentially avoiding the need for capture-recapture data collection in many instances.
Silvia Kollerova
Title: Demographics of antibiotic persistence
Authors: Silvia Kollerova, Lionel Jouvet, Ulrich Steiner
Affiliation: Max Planck Odense Center/ SDU
Abstract: Persister cells, cells that can survive antibiotic exposure but lack heritable antibiotic resistance, are assumed to play a crucial role for the evolution of antibiotic resistance. Persistence is a stage cells associated with reduced metabolic activity. Most previous studies have been done on batch cultures, rather than the individual level. Here, we used individual level bacteria data to confirm previous studies in how fast cells switch into a persistence stage, but our results challenge the fundamental idea that persistence comes with major costs of reduced growth (cell elongation) and division due to reduced metabolic activity. Persister cells and non-persister cells do not differ substantially in their division rate and there is mixed evidence about reduction in growth under certain conditions. In any case costs are much lower than previously assumed and suggest that persistence might even play a more prominent role for the evolution of resistance and failures of medical treatment by antibiotics.
Luke Eberhart-Phillips
Title: Demographic origins of avian mating system diversity
Authors: Luke J. Eberhart-Phillips, Tamás Székely, Joe Hoffman, Oliver Krüger
Affiliations: Department of Animal Behaviour, Bielefeld University, Bielefeld, Germany
Abstract: Adult sex ratios (ASRs) have profound consequences for the evolution of breeding behaviours and the conservation of wildlife populations. However, the origins of biased ASRs have remained elusive due to challenges of collecting detailed demographic data from wild populations. We studied six plover (Charadrius spp.) populations exhibiting different breeding systems to elucidate age- and sex-specific demographic contributions to ASR. To derive ASR, we employed two-sex Lefkovitch matrix models, parameterized with vital rates estimated with mark-recapture methods. ASR varied significantly among populations, with polygamous populations being biased and monogamous populations not. Sex-biased juvenile apparent survival contributed most to ASR bias.
Mary Towner
Title: Fertility Variation across American Indian Women in Early Oklahoma
Authors: Mary C. Towner, Abigail Andrews, Kermyt G. Anderson, and Mary K. Shenk
Affiliation: Oklahoma State University
Abstract: Human evolutionary demographers know little about the reproductive consequences of dispersal, particularly under adverse conditions. Between 1828 and 1887, tens of thousands of American Indians were relocated to Indian Territory (present-day Oklahoma) under US Government removal policies. The high mortality rates incurred by American Indians during this time are well-known, but how did women's fertility vary with social and ecological conditions? We use data from the 1910 US Federal Census to examine fertility variation across women from seven tribes with different relocation histories. We find preliminary evidence for substantial fertility variation by tribe, as well as by individual characteristics.
Viripi Lummaa
Title: Measuring changes in natural selection during a rapid demographic transition in human populations
Affiliation: University of Turku, Finland
Abstract: Rapid demographic changes can complicate our ability to quantify evolutionary processes, if the relationship between timescale and performance of a fitness metric is unknown, and the heritability of the traits in question changes. We used a dataset of a human population in Finland across 175 years of rapid demographic transition to low mortality and fertility rates (1) to directly compare two fitness metrics and their estimates of selection pressures, and (2) to quantify key heritabilities and genetic correlations before and during the demographic transition. Both metrics, lifetime reproductive success and an annual metric of individual performance, declined, while selection on the ages at first and last reproduction remained nearly constant, favoring individuals with wider reproductive windows. The ability to partition the annual metric into contributions from reproduction and survival allowed us to pick up details of the demographic transition: the short term effects of a severe famine and the reversal of selection pressure via the survival component, which favored individuals with narrow reproductive windows at the end of the demographic transition. We also found that key life-history traits were heritable both before and after the demographic transition, and allow a quantifiable genetic response to selection during both time periods. Further, the G matrices remained largely stable but revealed a trend for an increased additive genetic variance and thus evolutionary potential of the population after the transition.
Torrance Hanley
Title: Effects of intraspecific diversity on survivorship, growth, and recruitment of the Eastern Oyster across sites.
Authors: Torrance C. Hanley1, A. Randall Hughes1, Bethany Williams2, Hanna Garland2, and David L. Kimbro1
Affiliations: 1Marine Science Center, Northeastern University, Nahant, MA; 2Department of Biological Science, Florida State University, Tallahassee, FL;
Abstract: Intraspecific diversity, particularly of foundation species, affects community/ecosystem processes. Examining how genetic diversity relates to demography provides a link from genotypic/phenotypic variation to population dynamics. In a field experiment manipulating oyster diversity and predator exposure at two sites, we assessed the effects of cohort diversity and genetic relatedness on demographic traits across environments. Differences in predation between sites determined oyster survivorship. Without predation, both diversity metrics influenced survivorship, growth, and recruitment; each metric had distinct yet interdependent effects on vital rates. Intraspecific diversity affects demographic traits, yet magnitude and direction of these effects depend on diversity metric and environmental context.
Tom Miller
Title: Eco-evolutionary dynamics of range expansion
Authors: Tom Miller and Brad Ochocki
Affiliation: Rice University
Abstract:
John Hagga
Title: Research priorities of the National Institute on Aging
Affiliation: NIH/NIA
Tuesday 9:00-12:30
Mary Shenk
Title: What causes misperception of mortality rates?
Authors: Mary K. Shenk, Mary C. Towner, Amber Cox, and Nurul Alam
Affiliation: University of Missouri
Abstract: Mortality risk is a key driver of life history evolution, but few studies have assessed what cues humans use to evaluate these risks. Using data from Matlab, Bangladesh, we examine a phenomenon in which people experiencing economic development perceive mortality rates to be rising when in fact they are falling precipitously. We use a model selection approach to test whether inaccuracy in perceptions of mortality risk is better explained by (a) difficulty in estimating mortality rates due to demographic and ecological factors affecting the 'social diet', or (b) factors that render mortality less controllable (more extrinsic and less intrinsic).
Sean McMahon
Title: TBD-DBT: Trait-based Demography needs demography-based traits
Affiliation: Smithsonian Institution
Abstract: Efforts in the modeling forest ecosystems are following advances in the ecological community by aggregating species into functional types that appreciate physiological trade-offs through leaf and wood functional traits and while moving away from simple life-form descriptors (e.g., "high-wood density shade tolerant" vs. "tropical broad-leaf evergreen"). The links between functional traits, fitness, and the environment, however, remain highly problematic. I will discuss a new approach to aggregating species within and across forest communities by using carefully designed and estimated vital rate functions. Growth and survival functions take into account both ecological conditions and evolutionary trade-offs, while offering a pathway towards building new, more robust plant functional types. Further, these demographic functional types offer a new approach to how we quantitatively link more traditional tree functional traits to fitness and environmental conditions.
Hiroyuki Yokomizo
Title: Testing the influence of time since introduction on population growth and optimal management
Authors: Hiroyuki Yokomizo, Takenori Takada, John Lambrinos
Affiliation: National Institute for Environmental Sciences, Japan
Abstract: Several processes likely act to change the demographic rates of introduced species over time. However, we have a poor understanding of the degree to which the vital rates and population growth of introduced species change following initial introduction, or what the consequences of these dynamics are for optimal management. We used published matrix population models of introduced plant populations to describe relationships between time since introduction and population growth. We outline a general approach for testing the influence of time on invasive population dynamics, and we describe scenarios for how changing dynamics could influence optimal management.
Siobhán Mattison
Title: Adoption and mortality in historical Taiwan
Authors: Edmond Seabright1, Siobhán M. Mattison1, and Melissa J. Brown2
Affiliations: 1University of New Mexico, Department of Anthropology; 2Harvard-Yenching Institute, Harvard University
Abstract: Adoption has been hypothesized to increase the risk of mortality for children reared by non-relatives. Yet the sociological and economic contexts shaping decision-making around adoption are critical to understanding associated costs and benefits to adoptive parents. In this talk, we explore the association between adoption and mortality using data drawn from household registers in Taiwan from 1895-1945. We explore the risk of mortality for girls who were adopted as “little daughters-in-law” (ADIL) to serve as brides for co-resident boys and for girls adopted for any other reason (AD). Our previous research showed that adopted girls experienced lower or equivalent mortality compared to biological children being raised by their parents. In this more finely resolved analyses, we confirm that adopted girls experience lower mortality than their biological counterparts, but find that ADIL experience relatively higher mortality than AD. We interpret these findings in light of kin selection theory and the possible costs and benefits of adoption in historical Taiwan.
Holly Prendeville
Title: Life history and population dynamics across latitudes
Authors: Holly Prendeville1, Laura Galloway2
Affiliations: 1USFS Pacific Northwest Research Station, Corvallis, OR, University of Virginia
Abstract: Life history theory predicts that annual life history is favored under environmental conditions that allow for low mortality and high fecundity such as a long growing season, whereas the optimal strategy in areas with shorter growing seasons will have a higher proportion of biennials. To evaluate life history theory, we monitored 20 populations of the American Bellflower, Campanula americana, a monocarpic herb with a variable life history across a latitudinal transect for four years. The American Bellflower occurs in Eastern U.S., populations experience a negative relationship between latitude and climate (i.e. temperature and precipitation). Over three cohorts, life history form (proportion of annuals) was not associated with latitude. Contributions from annual plants to population growth rate had no relationship with latitude in the first two years of observation. In the final year of study, there was a negative relationship such that annuals had a greater contribution to population growth in southern populations than northern populations. This greater contribution of annuals to southern population growth matches life history theory predictions. However, finding such results for one in three cohorts suggests that local environmental factors may sometimes outweigh regional environmental patterns.
Ulrich Steiner
Title: Quantifying hidden individual heterogeneity
Authors: Ulrich Steiner, Adam Lenart, Jim Vaupel
Affiliations: Max Planck Odense Center/ SDU
Abstract: Aging is assumed to be driven by the accumulation of damage or some other aging factor which shapes demographic patterns, including the classical late age mortality plateaus. However to date, heterogeneity in these damage stages is not observed. Here, we estimate underlying stage distributions and stage dynamics, based on observed survival patterns of isoclonal bacteria. Our results reveal demographic dynamics being dominated by low damage stages and transmission of damage from mother to daughters is low. Still, our models are too simplistic and deterministic. Explaining the observed data requires more stochastic processes as our current models includes. We are only at the beginning of understanding the diverse mechanism behind aging and the shaping of senescence.
Takenori Takada
Title: The interactive effect of mast-seeding and disturbance on stochastic population growth rate in stage-structured model.
Authors: Takenor Takada1 and Yuko Kaneko2
Affiliations: 1 Hokkaido University and 2 Toyo University, Japan
Abstract: Tree populations suffer from environmental disturbances and show mast-seeding behavior and their temporal variations affect the vital rates of the populations. Disturbance and mast-seeding give the negative and positive effects on the population dynamics. Estimating the balance between those effects is one of the important subjects in the analysis of tree population dynamics. We constructed a matrix model and apply the model to Japanese riparian tree. The addressed questions are (i) Which vital rate and life stage strongly affect the stochastic population growth rate in each habitat? (ii) Is there any optimal combination of the frequencies of mast-seeding and disturbance?
Roberto Salguero-Gómez
Title: Life history tradeoffs modulate the speed of senescence in animals and plants
Authors: Rob Salguero-Gomez1,2,3,4 and Owen Jones5,6
Affiliations: 1 Department of Animal & Plant Sciences, University of Sheffield, Sheffield, UK.;2 Australian Research Council Centre of Excellence for Environmental Decisions, The University of Queensland, School of Biological Sciences, Queensland, Australia; 3 Evolutionary Biodemography Laboratory, Max Planck Institute for Demographic Research, Rostock, Germany; 4 School of Natural Sciences, Department of Zoology & Trinity Centre for Biodiversity Research, Trinity College Dublin, Ireland; 5 Max-Planck Odense Center on the Biodemography of Aging, University of Southern Denmark, Odense;6 Department of Biology, University of Southern Denmark, Odense.
Abstract: Longevity is one of the life history traits that most varies across the tree of life… but why? We used COMPADRE & COMADRE to explore how key life history traits are associated with the speed of senescence across >650 species of animals and plants. We found that the speed of senescence varies dramatically across the tree of life, and that it has a moderate phylogenetic signal when considering both plants and animals, but that this signal is stronger in animals than in plants, implying that processes other than evolutionary pressures must be responsible for this variation among plants. We found that iteroparous, slow-growing species are more likely to senesce slowly and thus attain long mature lifespans. We further examined the speed of senescence at two taxonomic levels: comparing kingdoms, with plants more likely to postpone senescence than animals, and comparing taxonomic classes, where we found that pine trees are particularly slow to senesce, followed by reptiles and sponges. Most mammals, birds, and the vast majority of fish in our analyses, senesce rapidly.
Steven Orzack
Title: Why are dinosaurs big and mammals are not?
Affiliation: Fresh Pond Research Institute, Cambridge, Mass.
Abstract: Based on a comment by Kurten (1953), Janis and Carrano (1992) surmised that “the presumed greater reproductive output of dinosaurs might make them less vulnerable to environmental perturbations than large mammals, and hence less vulnerable to extinction. This would provide an explanation for the observation that large dinosaur taxa were commonly seen in the Mesozoic while mammalian taxa of equivalent size were very rare in the Cenozoic.” We show that finite-time and ultimate extinction probabilities increase with the average potential for population increase. These theoretical results based on model life histories suggest that dinosaurs had higher ultimate and finite-time extinction probabilities as compared to those for mammals and that the evolution of large body size in dinosaurs is not explained by greater species longevity of dinosaurs as compared to mammals. Nonetheless, there could be an empirical relationship between body size and longevity; we describe the results of our empirical investigation of this relationship in the Dinosauria.
Mark Belk
Title: Comparative demography of two small stream fishes in response to variable stream flow
Authors: Mark C. Belk1, Josh Rasmussen2, Jeff Wesner3, and R. Cary Tuckfield4
Affiliations: 1Department of Biology, 4102LSB, Brigham Young University, Provo, Utah; 2U.S. Fish and Wildlife Service, Pacific Southwest Region, Klamath Falls, OR; 3Department of Biology, University of South Dakota, Vermillion, SD; 4Ecostatys, 105 Highland Forest Drive, Aiken, South Carolina.
Abstract: Populations of western stream fishes are strongly influenced by variation in stream flow driven by local climatic variation. Drought results in lowered stream flow and corresponding changes in survival and reproduction of stream fishes. To test for differences between species we conducted a long-term mark-recapture study on northern leatherside chub (Lepidomeda copei) and speckled dace (Rhinichthys osculus) in a small tributary of the Bear River (Yellow Creek) in southwestern Wyoming. Our three recapture efforts included one high water year and two extremely low water years. We calculated survival, transition, and fecundity estimates for “good” and “bad” years and compared resulting demography between years and species. In good years when populations are increasing, juveniles represent about ½ to 2/3 of the population for both species. Both survival and fecundity rates declined sharply in bad years for both species. Overall, speckled dace were demographically more resilient to bad years than northern leatherside chub. Small changes in incidence and severity of drought (or increased water withdrawals) will likely lead to extirpation of isolated populations of northern leatherside chub.
Glenda Wardle
Title: Contrasting spatial responses of mammal, reptile and plant populations to environmental change
Authors: Glenda Wardle, Chris Dickman, Aaron Greenville and Vuong Nguyen
Affiliations: Desert Ecology Research Group, University of Sydney, Australia
Abstract: A key goal in ecology is to determine the factors that influence the spatial dynamics of species’ populations and particularly for strongly event-driven systems such as arid central Australia.
Using multivariate state-space models we found the dominant grass responded to regional rainfall and wildfire and two rodent species, a carnivorous marsupial and one reptile species also exhibited synchrony. In contrast, an annual plant, two insectivorous marsupial and five reptile species exhibited asynchronous responses across the study region (8000km2).
As climatic shifts will exacerbate rainfall-drought cycles, future work should explore these divergent responses at different spatial scales across multiple dryland taxa.
Tuesday 2:00-5:30 Talks
Jessica E. Metcalf
Title: Trade-offs and the causes of mortality: a neglected driver of life history evolution
Affiliation: Princeton University
Abstract: An adaptive life-cycle emerges from a balance of trade-offs between fitness components. Evidence from a range of systems indicates that reproduction often comes at the cost of lower future survival, or that fast early growth trades off against lower adult survival. Although the field of physiology has increasingly focused on characterizing the proximate mechanisms underlying such trade-offs, trade-offs between causes of death have received proportionally little interest, despite their potential to shed light on the diversity of mortality pattern observed across the tree of life. This is mainly due to the scarcity of data on causes of death in nature; but also because of the diversity of evolutionary processes operating across the underlying functional systems shaping these causes of mortality. Here, we illustrate one example of trade-offs between different causes of mortality, contrasting immunopathology and infectious disease mortality, and exploring implications for evolution of host life history.
Lionel Jouvet
Title: Aging patterns in different environments
Affiliation: Max Planck Odense Center/ SDU
Abstract: Environmental and genetic variability shape demographic patterns, but in most studies these factors are not controlled. We can therefore only make indirect inferences on the demographic effect of such environmental and genetic drivers. Here, we show for isogenic individual E. coli bacteria, under highly controlled environments of a microfluidic device, how diverse demographic patterns arise. We reveal patterns from classical mortality plateaus to non-senescence, simply by changing the temperature or the nutrient source. Such strong environmental influences revealed within a single strain of bacteria challenges our fundamental theories about the evolutionary shaping of aging patterns. Further, this mature technology now allows to test other mechanisms shaping aging such as antibiotic resistance, stress response pathways, or genotype
Hal Caswell
Title: Individual stochasticity dominates the effects of heterogeneity in vital rates
Authors: Hal Caswell, Charlotte de Vries, Nienke Hartemink, Greg Roth, Nora Sanchez Gassen, and Silke van Daalen
Affiliations: Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam
Abstract: Evolutionary biology is fascinated by variance. Especially by variance reflecting genetic or phenotypic heterogeneity. Even more especially, by variance in traits connected with fitness. Demographic models of fitness, however, imply the existence of variance that reflects stochasticity at the individual level, not heterogeneity. Variance due to individual stochasticity is not available for natural selection; it may even diffuse the strength of selection. We give an update on techniques to quantify individual stochasticity and to partition variance into components due to heterogeneity and stochasticity. In both longevity and reproduction, stochasticity often swamps the effects of heterogeneity.
Lise Aubry
Title: Unobserved heterogeneity in vital rates creates a diversity of life history ‘complexes’ in an Antarctic seabird population
Authors: Stephanie Jenouvrier, Lise M. Aubry (presenter), Christophe Barbraud, Henri Weimerskirch, and Hal Caswell
Affiliations: Utah State University and Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam
Abstract: Decades of research have focused on measuring observed differences across individuals to understand their impact on vital rates and lifetime integrative outcomes (longevity). The impact of unobserved heterogeneity ‘UH’ in such traits has only recently been recognized by ecologists and is often only accounted for in survival rates. In the Southern fulmar, accounting for UH in all vital rates revealed trade-offs that would have gone undetected had we not accounted for it. Further, the relative contributions of UH and individual stochasticity differed among lifetime reproductive outcomes, showing the importance of accounting for both processes in life history studies.
Xi Song
Title: The Changing Demography of Multigenerational Relationships
Authors: Robert D. Mare1 and Xi Song2
Affiliation: 1University of California, Los Angeles, 2University of Chicago
Abstract: This paper reports analyses of the effects of demographic trends on the mutual exposure of grandparents and grandchildren and their consequences for multigenerational processes of social mobility in the United States from 1900 to 2010. We examine the effects of trends in longevity and levels and timing of fertility. Using historical vital statistics and stable population models, we extend prior work on this topic by providing a systematic analysis of grandparent-grandchild exposures from both prospective (grandparent) and retrospective (grandchild) perspectives. We also estimate exposure levels and trends specific to socioeconomic groups, as indicated by the education levels of grandparents and grandchildren, and investigate the sensitivity of our results to alternative assumptions about intergenerational social mobility, assortative mating, and family heterogeneity in fertility and mortality. We examine the implications of changes in mutual exposure of grandparent and grandchild generations for the associations between grandparents’ and grandchildren’s educational attainments.
James Carey
Title: Insect biodemography: A 21st century guided tour
Affiliation: University of California, Davis
Abstract: In my presentation I will describe and, in selected cases, reinterpret what I consider to be the most important findings of biodemographic research on insects that my colleagues, students and I have published over the past 25 years including results on insect lifespan, mortality, reproduction, health and population. I will discuss why these results are important and have stood the test of time (at least so far), point to areas in insect biodemography that I consider to be the most promising for future research, and situate them in the broader context of biodemography writ large.
Alexander Scheuerlein
Title: The Diversity of Aging within Species
Authors: Alexander Scheuerlein, Ralf Schaible, Maciej Danko, Annette Baudisch
Affiliation: Max Planck Institute for Demographic Research, Rostock, Germany
Abstract: A recent study by Jones et al. (2013) has shown that age-trajectories of mortality and fertility vary greatly across the tree of life. Only some organisms show increasing mortality and declining fertility after maturity, as predicted by the standard evolutionary theories of aging. Most organisms show other patterns such as increasing, constant, decreasing trajectories, and other shapes. Here, we ask the question how flexible the trajectories of mortality are within species, and focus on variation across populations. It is generally understood that the trajectories of mortality and fertility are moulded by a genotype to maximize fitness in a given environment. Consequently, we expect that mortality trajectories within a species should show at least some variation across environmental gradients. Here, we utilize Keyfitz’ entropy, a measure developed to measure inequality of deaths in human demography, to compare the variability of mortality trajectories across environments. Utilizing a unique dataset on more that 1000 mortality trajectories across a variety of organisms (DATLife, soon to be online, open access), we test the prediction that variability in both life expectancy and Keyfitz’ entropy is higher across populations within a species than the variability across timepoints.
Carol Horvitz
Title: Photosynthetic rates and population dynamics
Authors: Andrea Westerband and Carol Horvitz
Affiliation: University of Miami
Abstract: Temporal variability in light from gaps in the tree canopy strongly influences the vital rates of understory plants. From 2012-2015, we estimated the size-specific vital rates of two herbs, Calathea crotalifera and Heliconia tortuosa, over a range of light environments. We estimated maximum photosynthetic capacity (Amax) for a subset of individuals (N=39) during three annual censuses, and modelled future size as a linear function of current size (a plant trait that changes ontogenetically), canopy openness (an environmental variable), and Amax (a potentially plastic physiological plant trait). We estimated the population growth rates in deterministic (λ) and stochastic light environments (λS), using Integral Projection Models. As light availability increased, λ increased for Calathea but decreased for Heliconia, and increasing Amax had no effect on λ for Calathea but increased λ for Heliconia in low light. As Amax increased, λS increased for Heliconia, but not Calathea. Elasticity of λS to perturbations of: the vital rates in all environments (ES), the variance of the vital rates among environments (ESσ), and the vital rates in particular environments (ESβ) were influenced by Amax for Heliconia but not Calathea. Events that affect some vital rates in high light have a greater impact on overall fitness than events in shady environments, and there is greater potential for selection on traits of large individuals in high light than in low light
Jean-Michel Gaillard
Title: Which starts first, reproductive or actuarial senescence?
Authors: Jean-Michel Gaillard, Jean-François Lemaitre
Affiliation: CNRS, Lyon, France
Abstract:
Deborah Roach
Title: Welcome
Affiliation: University of Virginia
Anni Hämäläinen
Title: Fitness consequences of peak reproductive effort
Authors: AG McAdam, B Dantzer, JE Lane, S Boutin et al.
Affiliation: University of Alberta, Canada
Abstract: Breeding success of iteroparous species is often age-specific, showing improvement from onset of breeding until a peak in prime age, and a subsequent senescent decline. Despite its potential influence on fitness outcomes, the role of peak reproduction (i.e. maximum reproductive effort) has been largely overlooked in studies of life history evolution. We show that fluctuating resource availability leads to selection for reproductive flexibility and timing of peak reproductive effort to high anticipated fitness payoffs in red squirrels. Adjustments in peak reproductive effort significantly influence lifetime fitness, representing an important but overlooked component of the life history phenotype of iteroparous organisms.
Natalie Kerr
Title: Age-specific demography and lifetime reproductive success of native and exotic Pieris butterflies.”
Authors: Natalie Kerr, Elizabeth Crone, and Francie Chew.
Affiliation: Tufts University, Medford, MA.
Abstract: As individuals age through time, we often detect changes in life history processes, such as survival and reproduction. Collectively, these age-dependent processes govern the structure and dynamics of populations. Over the last century, we have seen a simultaneous decline of the native mustard white butterfly, Pieris oleracea, along with the introduction, spread, and proliferation of the introduced cabbage white butterfly, Pieris rapae. Here, we estimated survival and fecundity of both these Pieris species to delineate any differences in age-dependent vital rates. We found that the cabbage white has greater adult survival and fecundity only until around age 10 in days, then the native mustard white has greater survival and fecundity. Over their expected lifetime, we found that on average a female cabbage white contributes three times as more female eggs to the next generation than a female mustard white
Maya Groner
Title: Influence of life history plasticity on disease
Authors: Maya Groner, John Hoenig and Jeff Shields
Affiliation: Virginia Institute for Marine Science
Abstract: Diseases, particularly high-impact emerging diseases, place an enormous amount of selection pressure on host populations. The environmental factors that facilitate disease emergence are often associated with critical life history transitions which themselves may alter epidemiological processes (ie, transmission, susceptibility, and survival). For example, in the American lobster, increased temperatures are associated with molting, a key defense against epizootic shell disease (ESD). In the absence of molting, increased temperatures are also associated with increased disease incidence and severity. I am interested in how temperature-induced plasticity in molting may constrain or facilitate adaptation of lobsters to a novel disease stressor.
Aldo Compagnoni
Title: Climatic variability and population dynamics
Authors: Aldo Compagnoni, Andrew Bibian, and Tom Miller
Affiliation: Rice University
Abstract: Ecological theory emphasizes that climatic variability should decrease long-term stochastic population growth rate. However, climatic variability can in principle have neutral or positive effects as well. The effect of climatic variability depends on the relationship between climate factors and population growth rate. Concave, linear, and convex relationships have, respectively, negative, neutral, and positive long-term effects. We addressed how frequent these types of relationships are by compiling Long Term Ecological Research network data. Among the ~500 species we analyzed, 55% of relationships were linear or convex. Thus, our results question the emphasis of theory on the negative effects of environmental variability.
Daniel Harris
Title: Peruvian Genome Project: A study in Pre and Post Peruvian Inca Demography and their Evolutionary Dynamics
Authors: Daniel Harris1,2,3, Wei Song1,2,3, Amol Shetty1,2, Omar Cáceres4, Carlos Padilla4, Kelly Levano4, Víctor Borda5,6, Pedro Flores-Villanueva4, Omar Trujillo7, Cesar Sanchez4, David Tarazona4, Eduardo Tarazona5,6,Timothy D. O’Connor1,2,3, Heinner Guio4
Affiliations: 1Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD; 2Department of Medicine, University of Maryland School of Medicine, Baltimore, MD; 3Program in Personalized and Genomic Medicine, University of Maryland School of Medicine, Baltimore, MD; 4Laboratorio de Biología Molecular, Instituto Nacional de Salud, Lima, Perú; 5Departamento de Biologia Geral, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil; 6Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil; 7Centro Nacional de Salud Intercultural, Instituto Nacional de Salud, Lima, Perú
Abstract: We sequenced 150 and genotyped 130 Native American and Hispanic individuals from Peru to improve the understanding of Peruvian demography. All pairs of populations diverged approximately 10,000 years ago, which is in accordance with the hypothesis of rapid peopling of the Americas after the Last Glacial Maximum. We further constructed migration and diversity topography models of Peru which detected a migration corridor connecting the city centers in the Andes, Amazon, and Coast as well as showing the Andes as a barrier to gene flow. IBD networks showed the majority of migration to be from the Andes to the other regions.
Spencer Ingley
Title: Life-history evolution across stages of divergence
Authors: Spencer J. Ingley and Jerald B. Johnson
Affiliation: University of North Carolina, Chapel Hill
Abstract: How selection acts to drive trait evolution at different stages of divergence is of fundamental importance in our understanding of the origins of biodiversity. Yet, most studies have focused on a single point along an evolutionary trajectory. Here, we provide a case study evaluating the strength of divergent selection acting on life-history traits at early-versus-late stages of divergence in Brachyrhaphis fishes. We find that the difference in selection is stronger in the early-diverged population than the late-diverged population, and that trait differences acquired early are maintained over time.
Kevin Healy
Title: Mapping animal life-history strategies using the COMADRE database
Authors: Healy, K., Salguero-Gómez, R., Buckley, Y.M.
Affiliations: Trinity College, Dublin
Abstract: Understanding the patterns of life-history strategies is a central goal in comparative biology. While it is clear that trade-offs and constraints shape what life-history strategies are possible, the pattern of strategies across animals is still unclear. Using demographic data for a phylogenetically diverse range of species from the COMADRE database we test whether life-history traits follow expected patterns relating to body size constraints and expected trade-offs between reproduction and maintenance. We find that life-history traits scale with body size as predicted by metabolic theory and that the relationship between life history strategies is more complex than a singular fast-slow continuum.
Emily Schultz
Title: The importance of within-patch heterogeneity for metapopulation dynamics: applying scale transition theory to a size-structured metapopulation model
Authors: Emily Shultz and Tom EX Miller
Affiliation: Rice University
Abstract: When accounting for local environmental effects on larger-scale population dynamics, using average values is problematic if there are non-linear dynamics. Here we apply scale transition theory to scale from local to metapopulation dynamics, using a simulated population. We simulated a demographic dataset with non-linear relationships between an environmental variable and vital rates. We used Bayesian models to parameterize vital rate functions, including a non-linear term for environment. We then built two integral projection models: a mean field model and a scale transition model. The addition of the scale transition term resulted in a more accurate estimate of the population dynamics.
Jennifer Blake-Mahmud
Title: Changes in sex expression correlate with health in striped maple, Acer pensylvanicum (Sapindaceae)
Affiliation: Rutgers University
Abstract: In plants sex is usually a fixed trait, however, in rare species, a plant may change sex during its lifetime. One such species is striped maple, in which individuals can change sex repeatedly. Amongst five New Jersey populations, 30% of trees switched sex expression between 2014 and 2016. Preliminary data suggest that size, injury, and carbohydrate reserves may impact the frequency and direction of sex change. The switch from male to female correlates with increased carbohydrates the winter prior to flowering and with decreased health. The final floral sex is determined as late as three weeks prior to flowering.
Robert Shriver
Title: Bridging the gap between physiology and demography to understand climate change responses of a desert annual plant community
Affiliation: Duke University
Abstract: Tradeoffs have long been an essential part of the canon explaining high species diversity. Yet there has been a scarcity of linked demographic and physiological evidence to support the role of resource use tradeoffs in natural systems. Using Chihuahuan desert annual plants, I show that demographic tradeoffs driven by soil moisture variation allow multiple species to partition a limiting resource. Specifically, by achieving highest fitness in either rainfall pulse or interpulse periods, species exploit temporal niche differences that could allow coexistence on a shared resource. Differences in fitness are explained in part by response of photosynthesis to changing soil moisture.
Will Petry
Title: Partitioning the linear and non-linear effects of climate change on two-sex population dynamics
Authors: William K. Petry1,4, Tom E.X. Miller2, Judy D. Soule4, Kailen A. Mooney3,4
Affiliations: 1Institute of Integrative Biology, ETH Zürich, Switzerland; 2Department of BioSciences, Program in Ecology & Evolutionary Biology, Rice University, Houston, Texas, USA; 3Department of Ecology & Evolutionary Biology, University of California, Irvine, California USA; 4Rocky Mountain Biological Laboratory, Gothic, Colorado, USA.
Abstract: Males and females may have sex-specific responses to environmental change. Responses of either sex may directly affect population dynamics, but may also bias operational sex ratios (OSRs) and limit reproduction. We partitioned the demographic effects of climate change on a long-lived dioecious herb using a two-sex demographic model, parameterized with contemporary and historic data. Changing aridity over the species elevation range and over the past 40 years had sex-specific effects on vital rates, sufficient to explain observed skews in OSR and strongly limit mating. Population growth rates were robust to OSR changes; however, the loss of propagules may dampen range expansion as climate change continues.
Monday 1:40-5:00
Emily Bruns
Title: Demography of disease in natural plant populations: host lifespan and the evolution of resistance
Affiliation: University of Virginia
Abstract: Disease can strongly impact the ecology and evolution of natural populations by reducing population growth rate and generating selection for disease-resistance traits. Demographic studies offer a window into both these processes: We have been using a long-term demographic study of a vector-transmitted sterilizing disease in a long-lived population of wild carnations to understand how host life history traits influence host resistance and transmission of a vector-transmitted sterilizing disease in a long-lived population of wild carnations. Through this work we have found that longer-lived hosts can evolve resistance more rapidly than shorter-lived hosts, and are less likely to maintain resistance polymorphisms. We have also found that resistance increases with age, and that this age-specific resistance has important consequences for transmission dynamics.
Robert Richardson
Title: Probabilistic Integral Population Models
Authors: Robert Richardson and Mark Belk
Affiliation: Brigham Young University
Abstract: A hierarchical Bayesian model using a Poisson process likelihood and an integral population model framework can be a flexible approach to modeling demographics over time. We show how the long-term growth rate, sensitivity, and elasticity can be calculated using this approach and compare the results with estimates from matrix population models. Through simulation studies, we show how the parameters of the growth, survival, and other functions in the integral population model can be estimated with only the time profiles, potentially avoiding the need for capture-recapture data collection in many instances.
Silvia Kollerova
Title: Demographics of antibiotic persistence
Authors: Silvia Kollerova, Lionel Jouvet, Ulrich Steiner
Affiliation: Max Planck Odense Center/ SDU
Abstract: Persister cells, cells that can survive antibiotic exposure but lack heritable antibiotic resistance, are assumed to play a crucial role for the evolution of antibiotic resistance. Persistence is a stage cells associated with reduced metabolic activity. Most previous studies have been done on batch cultures, rather than the individual level. Here, we used individual level bacteria data to confirm previous studies in how fast cells switch into a persistence stage, but our results challenge the fundamental idea that persistence comes with major costs of reduced growth (cell elongation) and division due to reduced metabolic activity. Persister cells and non-persister cells do not differ substantially in their division rate and there is mixed evidence about reduction in growth under certain conditions. In any case costs are much lower than previously assumed and suggest that persistence might even play a more prominent role for the evolution of resistance and failures of medical treatment by antibiotics.
Luke Eberhart-Phillips
Title: Demographic origins of avian mating system diversity
Authors: Luke J. Eberhart-Phillips, Tamás Székely, Joe Hoffman, Oliver Krüger
Affiliations: Department of Animal Behaviour, Bielefeld University, Bielefeld, Germany
Abstract: Adult sex ratios (ASRs) have profound consequences for the evolution of breeding behaviours and the conservation of wildlife populations. However, the origins of biased ASRs have remained elusive due to challenges of collecting detailed demographic data from wild populations. We studied six plover (Charadrius spp.) populations exhibiting different breeding systems to elucidate age- and sex-specific demographic contributions to ASR. To derive ASR, we employed two-sex Lefkovitch matrix models, parameterized with vital rates estimated with mark-recapture methods. ASR varied significantly among populations, with polygamous populations being biased and monogamous populations not. Sex-biased juvenile apparent survival contributed most to ASR bias.
Mary Towner
Title: Fertility Variation across American Indian Women in Early Oklahoma
Authors: Mary C. Towner, Abigail Andrews, Kermyt G. Anderson, and Mary K. Shenk
Affiliation: Oklahoma State University
Abstract: Human evolutionary demographers know little about the reproductive consequences of dispersal, particularly under adverse conditions. Between 1828 and 1887, tens of thousands of American Indians were relocated to Indian Territory (present-day Oklahoma) under US Government removal policies. The high mortality rates incurred by American Indians during this time are well-known, but how did women's fertility vary with social and ecological conditions? We use data from the 1910 US Federal Census to examine fertility variation across women from seven tribes with different relocation histories. We find preliminary evidence for substantial fertility variation by tribe, as well as by individual characteristics.
Viripi Lummaa
Title: Measuring changes in natural selection during a rapid demographic transition in human populations
Affiliation: University of Turku, Finland
Abstract: Rapid demographic changes can complicate our ability to quantify evolutionary processes, if the relationship between timescale and performance of a fitness metric is unknown, and the heritability of the traits in question changes. We used a dataset of a human population in Finland across 175 years of rapid demographic transition to low mortality and fertility rates (1) to directly compare two fitness metrics and their estimates of selection pressures, and (2) to quantify key heritabilities and genetic correlations before and during the demographic transition. Both metrics, lifetime reproductive success and an annual metric of individual performance, declined, while selection on the ages at first and last reproduction remained nearly constant, favoring individuals with wider reproductive windows. The ability to partition the annual metric into contributions from reproduction and survival allowed us to pick up details of the demographic transition: the short term effects of a severe famine and the reversal of selection pressure via the survival component, which favored individuals with narrow reproductive windows at the end of the demographic transition. We also found that key life-history traits were heritable both before and after the demographic transition, and allow a quantifiable genetic response to selection during both time periods. Further, the G matrices remained largely stable but revealed a trend for an increased additive genetic variance and thus evolutionary potential of the population after the transition.
Torrance Hanley
Title: Effects of intraspecific diversity on survivorship, growth, and recruitment of the Eastern Oyster across sites.
Authors: Torrance C. Hanley1, A. Randall Hughes1, Bethany Williams2, Hanna Garland2, and David L. Kimbro1
Affiliations: 1Marine Science Center, Northeastern University, Nahant, MA; 2Department of Biological Science, Florida State University, Tallahassee, FL;
Abstract: Intraspecific diversity, particularly of foundation species, affects community/ecosystem processes. Examining how genetic diversity relates to demography provides a link from genotypic/phenotypic variation to population dynamics. In a field experiment manipulating oyster diversity and predator exposure at two sites, we assessed the effects of cohort diversity and genetic relatedness on demographic traits across environments. Differences in predation between sites determined oyster survivorship. Without predation, both diversity metrics influenced survivorship, growth, and recruitment; each metric had distinct yet interdependent effects on vital rates. Intraspecific diversity affects demographic traits, yet magnitude and direction of these effects depend on diversity metric and environmental context.
Tom Miller
Title: Eco-evolutionary dynamics of range expansion
Authors: Tom Miller and Brad Ochocki
Affiliation: Rice University
Abstract:
John Hagga
Title: Research priorities of the National Institute on Aging
Affiliation: NIH/NIA
Tuesday 9:00-12:30
Mary Shenk
Title: What causes misperception of mortality rates?
Authors: Mary K. Shenk, Mary C. Towner, Amber Cox, and Nurul Alam
Affiliation: University of Missouri
Abstract: Mortality risk is a key driver of life history evolution, but few studies have assessed what cues humans use to evaluate these risks. Using data from Matlab, Bangladesh, we examine a phenomenon in which people experiencing economic development perceive mortality rates to be rising when in fact they are falling precipitously. We use a model selection approach to test whether inaccuracy in perceptions of mortality risk is better explained by (a) difficulty in estimating mortality rates due to demographic and ecological factors affecting the 'social diet', or (b) factors that render mortality less controllable (more extrinsic and less intrinsic).
Sean McMahon
Title: TBD-DBT: Trait-based Demography needs demography-based traits
Affiliation: Smithsonian Institution
Abstract: Efforts in the modeling forest ecosystems are following advances in the ecological community by aggregating species into functional types that appreciate physiological trade-offs through leaf and wood functional traits and while moving away from simple life-form descriptors (e.g., "high-wood density shade tolerant" vs. "tropical broad-leaf evergreen"). The links between functional traits, fitness, and the environment, however, remain highly problematic. I will discuss a new approach to aggregating species within and across forest communities by using carefully designed and estimated vital rate functions. Growth and survival functions take into account both ecological conditions and evolutionary trade-offs, while offering a pathway towards building new, more robust plant functional types. Further, these demographic functional types offer a new approach to how we quantitatively link more traditional tree functional traits to fitness and environmental conditions.
Hiroyuki Yokomizo
Title: Testing the influence of time since introduction on population growth and optimal management
Authors: Hiroyuki Yokomizo, Takenori Takada, John Lambrinos
Affiliation: National Institute for Environmental Sciences, Japan
Abstract: Several processes likely act to change the demographic rates of introduced species over time. However, we have a poor understanding of the degree to which the vital rates and population growth of introduced species change following initial introduction, or what the consequences of these dynamics are for optimal management. We used published matrix population models of introduced plant populations to describe relationships between time since introduction and population growth. We outline a general approach for testing the influence of time on invasive population dynamics, and we describe scenarios for how changing dynamics could influence optimal management.
Siobhán Mattison
Title: Adoption and mortality in historical Taiwan
Authors: Edmond Seabright1, Siobhán M. Mattison1, and Melissa J. Brown2
Affiliations: 1University of New Mexico, Department of Anthropology; 2Harvard-Yenching Institute, Harvard University
Abstract: Adoption has been hypothesized to increase the risk of mortality for children reared by non-relatives. Yet the sociological and economic contexts shaping decision-making around adoption are critical to understanding associated costs and benefits to adoptive parents. In this talk, we explore the association between adoption and mortality using data drawn from household registers in Taiwan from 1895-1945. We explore the risk of mortality for girls who were adopted as “little daughters-in-law” (ADIL) to serve as brides for co-resident boys and for girls adopted for any other reason (AD). Our previous research showed that adopted girls experienced lower or equivalent mortality compared to biological children being raised by their parents. In this more finely resolved analyses, we confirm that adopted girls experience lower mortality than their biological counterparts, but find that ADIL experience relatively higher mortality than AD. We interpret these findings in light of kin selection theory and the possible costs and benefits of adoption in historical Taiwan.
Holly Prendeville
Title: Life history and population dynamics across latitudes
Authors: Holly Prendeville1, Laura Galloway2
Affiliations: 1USFS Pacific Northwest Research Station, Corvallis, OR, University of Virginia
Abstract: Life history theory predicts that annual life history is favored under environmental conditions that allow for low mortality and high fecundity such as a long growing season, whereas the optimal strategy in areas with shorter growing seasons will have a higher proportion of biennials. To evaluate life history theory, we monitored 20 populations of the American Bellflower, Campanula americana, a monocarpic herb with a variable life history across a latitudinal transect for four years. The American Bellflower occurs in Eastern U.S., populations experience a negative relationship between latitude and climate (i.e. temperature and precipitation). Over three cohorts, life history form (proportion of annuals) was not associated with latitude. Contributions from annual plants to population growth rate had no relationship with latitude in the first two years of observation. In the final year of study, there was a negative relationship such that annuals had a greater contribution to population growth in southern populations than northern populations. This greater contribution of annuals to southern population growth matches life history theory predictions. However, finding such results for one in three cohorts suggests that local environmental factors may sometimes outweigh regional environmental patterns.
Ulrich Steiner
Title: Quantifying hidden individual heterogeneity
Authors: Ulrich Steiner, Adam Lenart, Jim Vaupel
Affiliations: Max Planck Odense Center/ SDU
Abstract: Aging is assumed to be driven by the accumulation of damage or some other aging factor which shapes demographic patterns, including the classical late age mortality plateaus. However to date, heterogeneity in these damage stages is not observed. Here, we estimate underlying stage distributions and stage dynamics, based on observed survival patterns of isoclonal bacteria. Our results reveal demographic dynamics being dominated by low damage stages and transmission of damage from mother to daughters is low. Still, our models are too simplistic and deterministic. Explaining the observed data requires more stochastic processes as our current models includes. We are only at the beginning of understanding the diverse mechanism behind aging and the shaping of senescence.
Takenori Takada
Title: The interactive effect of mast-seeding and disturbance on stochastic population growth rate in stage-structured model.
Authors: Takenor Takada1 and Yuko Kaneko2
Affiliations: 1 Hokkaido University and 2 Toyo University, Japan
Abstract: Tree populations suffer from environmental disturbances and show mast-seeding behavior and their temporal variations affect the vital rates of the populations. Disturbance and mast-seeding give the negative and positive effects on the population dynamics. Estimating the balance between those effects is one of the important subjects in the analysis of tree population dynamics. We constructed a matrix model and apply the model to Japanese riparian tree. The addressed questions are (i) Which vital rate and life stage strongly affect the stochastic population growth rate in each habitat? (ii) Is there any optimal combination of the frequencies of mast-seeding and disturbance?
Roberto Salguero-Gómez
Title: Life history tradeoffs modulate the speed of senescence in animals and plants
Authors: Rob Salguero-Gomez1,2,3,4 and Owen Jones5,6
Affiliations: 1 Department of Animal & Plant Sciences, University of Sheffield, Sheffield, UK.;2 Australian Research Council Centre of Excellence for Environmental Decisions, The University of Queensland, School of Biological Sciences, Queensland, Australia; 3 Evolutionary Biodemography Laboratory, Max Planck Institute for Demographic Research, Rostock, Germany; 4 School of Natural Sciences, Department of Zoology & Trinity Centre for Biodiversity Research, Trinity College Dublin, Ireland; 5 Max-Planck Odense Center on the Biodemography of Aging, University of Southern Denmark, Odense;6 Department of Biology, University of Southern Denmark, Odense.
Abstract: Longevity is one of the life history traits that most varies across the tree of life… but why? We used COMPADRE & COMADRE to explore how key life history traits are associated with the speed of senescence across >650 species of animals and plants. We found that the speed of senescence varies dramatically across the tree of life, and that it has a moderate phylogenetic signal when considering both plants and animals, but that this signal is stronger in animals than in plants, implying that processes other than evolutionary pressures must be responsible for this variation among plants. We found that iteroparous, slow-growing species are more likely to senesce slowly and thus attain long mature lifespans. We further examined the speed of senescence at two taxonomic levels: comparing kingdoms, with plants more likely to postpone senescence than animals, and comparing taxonomic classes, where we found that pine trees are particularly slow to senesce, followed by reptiles and sponges. Most mammals, birds, and the vast majority of fish in our analyses, senesce rapidly.
Steven Orzack
Title: Why are dinosaurs big and mammals are not?
Affiliation: Fresh Pond Research Institute, Cambridge, Mass.
Abstract: Based on a comment by Kurten (1953), Janis and Carrano (1992) surmised that “the presumed greater reproductive output of dinosaurs might make them less vulnerable to environmental perturbations than large mammals, and hence less vulnerable to extinction. This would provide an explanation for the observation that large dinosaur taxa were commonly seen in the Mesozoic while mammalian taxa of equivalent size were very rare in the Cenozoic.” We show that finite-time and ultimate extinction probabilities increase with the average potential for population increase. These theoretical results based on model life histories suggest that dinosaurs had higher ultimate and finite-time extinction probabilities as compared to those for mammals and that the evolution of large body size in dinosaurs is not explained by greater species longevity of dinosaurs as compared to mammals. Nonetheless, there could be an empirical relationship between body size and longevity; we describe the results of our empirical investigation of this relationship in the Dinosauria.
Mark Belk
Title: Comparative demography of two small stream fishes in response to variable stream flow
Authors: Mark C. Belk1, Josh Rasmussen2, Jeff Wesner3, and R. Cary Tuckfield4
Affiliations: 1Department of Biology, 4102LSB, Brigham Young University, Provo, Utah; 2U.S. Fish and Wildlife Service, Pacific Southwest Region, Klamath Falls, OR; 3Department of Biology, University of South Dakota, Vermillion, SD; 4Ecostatys, 105 Highland Forest Drive, Aiken, South Carolina.
Abstract: Populations of western stream fishes are strongly influenced by variation in stream flow driven by local climatic variation. Drought results in lowered stream flow and corresponding changes in survival and reproduction of stream fishes. To test for differences between species we conducted a long-term mark-recapture study on northern leatherside chub (Lepidomeda copei) and speckled dace (Rhinichthys osculus) in a small tributary of the Bear River (Yellow Creek) in southwestern Wyoming. Our three recapture efforts included one high water year and two extremely low water years. We calculated survival, transition, and fecundity estimates for “good” and “bad” years and compared resulting demography between years and species. In good years when populations are increasing, juveniles represent about ½ to 2/3 of the population for both species. Both survival and fecundity rates declined sharply in bad years for both species. Overall, speckled dace were demographically more resilient to bad years than northern leatherside chub. Small changes in incidence and severity of drought (or increased water withdrawals) will likely lead to extirpation of isolated populations of northern leatherside chub.
Glenda Wardle
Title: Contrasting spatial responses of mammal, reptile and plant populations to environmental change
Authors: Glenda Wardle, Chris Dickman, Aaron Greenville and Vuong Nguyen
Affiliations: Desert Ecology Research Group, University of Sydney, Australia
Abstract: A key goal in ecology is to determine the factors that influence the spatial dynamics of species’ populations and particularly for strongly event-driven systems such as arid central Australia.
Using multivariate state-space models we found the dominant grass responded to regional rainfall and wildfire and two rodent species, a carnivorous marsupial and one reptile species also exhibited synchrony. In contrast, an annual plant, two insectivorous marsupial and five reptile species exhibited asynchronous responses across the study region (8000km2).
As climatic shifts will exacerbate rainfall-drought cycles, future work should explore these divergent responses at different spatial scales across multiple dryland taxa.
Tuesday 2:00-5:30 Talks
Jessica E. Metcalf
Title: Trade-offs and the causes of mortality: a neglected driver of life history evolution
Affiliation: Princeton University
Abstract: An adaptive life-cycle emerges from a balance of trade-offs between fitness components. Evidence from a range of systems indicates that reproduction often comes at the cost of lower future survival, or that fast early growth trades off against lower adult survival. Although the field of physiology has increasingly focused on characterizing the proximate mechanisms underlying such trade-offs, trade-offs between causes of death have received proportionally little interest, despite their potential to shed light on the diversity of mortality pattern observed across the tree of life. This is mainly due to the scarcity of data on causes of death in nature; but also because of the diversity of evolutionary processes operating across the underlying functional systems shaping these causes of mortality. Here, we illustrate one example of trade-offs between different causes of mortality, contrasting immunopathology and infectious disease mortality, and exploring implications for evolution of host life history.
Lionel Jouvet
Title: Aging patterns in different environments
Affiliation: Max Planck Odense Center/ SDU
Abstract: Environmental and genetic variability shape demographic patterns, but in most studies these factors are not controlled. We can therefore only make indirect inferences on the demographic effect of such environmental and genetic drivers. Here, we show for isogenic individual E. coli bacteria, under highly controlled environments of a microfluidic device, how diverse demographic patterns arise. We reveal patterns from classical mortality plateaus to non-senescence, simply by changing the temperature or the nutrient source. Such strong environmental influences revealed within a single strain of bacteria challenges our fundamental theories about the evolutionary shaping of aging patterns. Further, this mature technology now allows to test other mechanisms shaping aging such as antibiotic resistance, stress response pathways, or genotype
Hal Caswell
Title: Individual stochasticity dominates the effects of heterogeneity in vital rates
Authors: Hal Caswell, Charlotte de Vries, Nienke Hartemink, Greg Roth, Nora Sanchez Gassen, and Silke van Daalen
Affiliations: Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam
Abstract: Evolutionary biology is fascinated by variance. Especially by variance reflecting genetic or phenotypic heterogeneity. Even more especially, by variance in traits connected with fitness. Demographic models of fitness, however, imply the existence of variance that reflects stochasticity at the individual level, not heterogeneity. Variance due to individual stochasticity is not available for natural selection; it may even diffuse the strength of selection. We give an update on techniques to quantify individual stochasticity and to partition variance into components due to heterogeneity and stochasticity. In both longevity and reproduction, stochasticity often swamps the effects of heterogeneity.
Lise Aubry
Title: Unobserved heterogeneity in vital rates creates a diversity of life history ‘complexes’ in an Antarctic seabird population
Authors: Stephanie Jenouvrier, Lise M. Aubry (presenter), Christophe Barbraud, Henri Weimerskirch, and Hal Caswell
Affiliations: Utah State University and Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam
Abstract: Decades of research have focused on measuring observed differences across individuals to understand their impact on vital rates and lifetime integrative outcomes (longevity). The impact of unobserved heterogeneity ‘UH’ in such traits has only recently been recognized by ecologists and is often only accounted for in survival rates. In the Southern fulmar, accounting for UH in all vital rates revealed trade-offs that would have gone undetected had we not accounted for it. Further, the relative contributions of UH and individual stochasticity differed among lifetime reproductive outcomes, showing the importance of accounting for both processes in life history studies.
Xi Song
Title: The Changing Demography of Multigenerational Relationships
Authors: Robert D. Mare1 and Xi Song2
Affiliation: 1University of California, Los Angeles, 2University of Chicago
Abstract: This paper reports analyses of the effects of demographic trends on the mutual exposure of grandparents and grandchildren and their consequences for multigenerational processes of social mobility in the United States from 1900 to 2010. We examine the effects of trends in longevity and levels and timing of fertility. Using historical vital statistics and stable population models, we extend prior work on this topic by providing a systematic analysis of grandparent-grandchild exposures from both prospective (grandparent) and retrospective (grandchild) perspectives. We also estimate exposure levels and trends specific to socioeconomic groups, as indicated by the education levels of grandparents and grandchildren, and investigate the sensitivity of our results to alternative assumptions about intergenerational social mobility, assortative mating, and family heterogeneity in fertility and mortality. We examine the implications of changes in mutual exposure of grandparent and grandchild generations for the associations between grandparents’ and grandchildren’s educational attainments.
James Carey
Title: Insect biodemography: A 21st century guided tour
Affiliation: University of California, Davis
Abstract: In my presentation I will describe and, in selected cases, reinterpret what I consider to be the most important findings of biodemographic research on insects that my colleagues, students and I have published over the past 25 years including results on insect lifespan, mortality, reproduction, health and population. I will discuss why these results are important and have stood the test of time (at least so far), point to areas in insect biodemography that I consider to be the most promising for future research, and situate them in the broader context of biodemography writ large.
Alexander Scheuerlein
Title: The Diversity of Aging within Species
Authors: Alexander Scheuerlein, Ralf Schaible, Maciej Danko, Annette Baudisch
Affiliation: Max Planck Institute for Demographic Research, Rostock, Germany
Abstract: A recent study by Jones et al. (2013) has shown that age-trajectories of mortality and fertility vary greatly across the tree of life. Only some organisms show increasing mortality and declining fertility after maturity, as predicted by the standard evolutionary theories of aging. Most organisms show other patterns such as increasing, constant, decreasing trajectories, and other shapes. Here, we ask the question how flexible the trajectories of mortality are within species, and focus on variation across populations. It is generally understood that the trajectories of mortality and fertility are moulded by a genotype to maximize fitness in a given environment. Consequently, we expect that mortality trajectories within a species should show at least some variation across environmental gradients. Here, we utilize Keyfitz’ entropy, a measure developed to measure inequality of deaths in human demography, to compare the variability of mortality trajectories across environments. Utilizing a unique dataset on more that 1000 mortality trajectories across a variety of organisms (DATLife, soon to be online, open access), we test the prediction that variability in both life expectancy and Keyfitz’ entropy is higher across populations within a species than the variability across timepoints.
Carol Horvitz
Title: Photosynthetic rates and population dynamics
Authors: Andrea Westerband and Carol Horvitz
Affiliation: University of Miami
Abstract: Temporal variability in light from gaps in the tree canopy strongly influences the vital rates of understory plants. From 2012-2015, we estimated the size-specific vital rates of two herbs, Calathea crotalifera and Heliconia tortuosa, over a range of light environments. We estimated maximum photosynthetic capacity (Amax) for a subset of individuals (N=39) during three annual censuses, and modelled future size as a linear function of current size (a plant trait that changes ontogenetically), canopy openness (an environmental variable), and Amax (a potentially plastic physiological plant trait). We estimated the population growth rates in deterministic (λ) and stochastic light environments (λS), using Integral Projection Models. As light availability increased, λ increased for Calathea but decreased for Heliconia, and increasing Amax had no effect on λ for Calathea but increased λ for Heliconia in low light. As Amax increased, λS increased for Heliconia, but not Calathea. Elasticity of λS to perturbations of: the vital rates in all environments (ES), the variance of the vital rates among environments (ESσ), and the vital rates in particular environments (ESβ) were influenced by Amax for Heliconia but not Calathea. Events that affect some vital rates in high light have a greater impact on overall fitness than events in shady environments, and there is greater potential for selection on traits of large individuals in high light than in low light
Jean-Michel Gaillard
Title: Which starts first, reproductive or actuarial senescence?
Authors: Jean-Michel Gaillard, Jean-François Lemaitre
Affiliation: CNRS, Lyon, France
Abstract: