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Sex-Specific Survival To Maturity And The Evolution Of Environmental Sex Determination, Lisa E. Schwanz, Gerardo Antonio Cordero, Eric L. Charnov, Fredric J. Janzen Feb 2016

Sex-Specific Survival To Maturity And The Evolution Of Environmental Sex Determination, Lisa E. Schwanz, Gerardo Antonio Cordero, Eric L. Charnov, Fredric J. Janzen

Ecology, Evolution and Organismal Biology Publications

Four decades ago, it was proposed that environmental sex determination (ESD) evolves when individual fitness depends on the environment in a sex-specific fashion—a form of condition-dependent sex allocation. Many biological processes have been hypothesized to drive this sex asymmetry, yet a general explanation for the evolution of sex-determining mechanisms remains elusive. Here, we develop a mathematical model for a novel hypothesis of the evolution of ESD, and provide a first empirical test using data across turtles. ESD is favored when the sex-determining environment affects annual survival rates equivalently in males and females, and males and females mature at different ...


Female And Male Life Tables For Seven Wild Primate Species, Anne M. Bronikowski, Marina Cords, Susan C. Alberts, Jeanne Altmann, Diane K. Brockman, Linda M. Fedigan, Anne Pusey, Tara Stoinski, Karen B. Strier, William F. Morris Jan 2016

Female And Male Life Tables For Seven Wild Primate Species, Anne M. Bronikowski, Marina Cords, Susan C. Alberts, Jeanne Altmann, Diane K. Brockman, Linda M. Fedigan, Anne Pusey, Tara Stoinski, Karen B. Strier, William F. Morris

Ecology, Evolution and Organismal Biology Publications

We provide male and female census count data, age-specific survivorship, and female age-specific fertility estimates for populations of seven wild primates that have been continuously monitored for at least 29 years: sifaka (Propithecus verreauxi) in Madagascar; muriqui (Brachyteles hypoxanthus) in Brazil; capuchin (Cebus capucinus) in Costa Rica; baboon (Papio cynocephalus) and blue monkey (Cercopithecus mitis) in Kenya; chimpanzee (Pan troglodytes) in Tanzania; and gorilla (Gorilla beringei) in Rwanda. Using one-year age-class intervals, we computed point estimates of age-specific survival for both sexes. In all species, our survival estimates for the dispersing sex are affected by heavy censoring. We also calculated ...


Hormonal And Metabolic Responses To Upper Temperature Extremes In Divergent Life-History Ecotypes Of A Garter Snake, Eric J. Gangloff, Kaitlyn G. Holden, Rory S. Telemeco, Lance H. Baumgard, Anne M. Bronikowski Jan 2016

Hormonal And Metabolic Responses To Upper Temperature Extremes In Divergent Life-History Ecotypes Of A Garter Snake, Eric J. Gangloff, Kaitlyn G. Holden, Rory S. Telemeco, Lance H. Baumgard, Anne M. Bronikowski

Ecology, Evolution and Organismal Biology Publications

Extreme temperatures constrain organismal physiology and impose both acute and chronic effects. Additionally, temperature-induced hormone-mediated stress response pathways and energetic trade-offs are important drivers of life-history variation. This study employs an integrative approach to quantify acute physiological responses to high temperatures in divergent life-history ecotypes of the western terrestrial garter snake (Thamnophis elegans). Using wild-caught animals, we measured oxygen consumption rate and physiological markers of hormonal stress response, energy availability and anaerobic respiration in blood plasma across five ecologically relevant temperatures (24, 28, 32, 35 and 38°C; 3 h exposure). Corticosterone, insulin and glucose concentrations all increased with temperature ...


Decades Of Field Data Reveal That Turtles Senesce In The Wild, Daniel A. Warner, David A. W. Miller, Anne M. Bronikowski, Fredric J. Janzen Jan 2016

Decades Of Field Data Reveal That Turtles Senesce In The Wild, Daniel A. Warner, David A. W. Miller, Anne M. Bronikowski, Fredric J. Janzen

Ecology, Evolution and Organismal Biology Publications

Lifespan and aging rates vary considerably across taxa; thus, understanding the factors that lead to this variation is a primary goal in biology and has ramifications for understanding constraints and flexibility in human aging. Theory predicts that senescence—declining reproduction and increasing mortality with advancing age—evolves when selection against harmful mutations is weaker at old ages relative to young ages or when selection favors pleiotropic alleles with beneficial effects early in life despite late-life costs. However, in many long-lived ectotherms, selection is expected to remain strong at old ages because reproductive output typically increases with age, which may lead ...


Developmental And Immediate Thermal Environments Shape Energetic Trade-Offs, Growth Efficiency, And Metabolic Rate In Divergent Life-History Ecotypes Of The Garter Snake Thamnophis Elegans, Eric J. Gangloff, David Vleck, Anne M. Bronikowski Jan 2015

Developmental And Immediate Thermal Environments Shape Energetic Trade-Offs, Growth Efficiency, And Metabolic Rate In Divergent Life-History Ecotypes Of The Garter Snake Thamnophis Elegans, Eric J. Gangloff, David Vleck, Anne M. Bronikowski

Ecology, Evolution and Organismal Biology Publications

Interactions at all levels of ecology are influenced by the rate at which energy is obtained, converted, and allocated. Tradeoffs in energy allocation within individuals in turn form the basis for life-history theory. Here we describe tests of the influences of temperature, developmental environment, and genetic background on measures of growth efficiency and resting metabolic rate in an ectothermic vertebrate, the western terrestrial garter snake (Thamnophis elegans). After raising captive-born snakes from divergent life-history ecotypes on thermal regimes mimicking natural habitat differences (2#2 experimental design of ecotype and thermal environment), we measured oxygen consumption rate at temperatures spanning the ...


Widespread Rapid Reductions In Body Size Of Adult Salamanders In Response To Climate Change, Nicholas M. Caruso, Michael W. Sears, Dean C. Adams, Karen R. Lips Jun 2014

Widespread Rapid Reductions In Body Size Of Adult Salamanders In Response To Climate Change, Nicholas M. Caruso, Michael W. Sears, Dean C. Adams, Karen R. Lips

Ecology, Evolution and Organismal Biology Publications

Reduction in body size is a major response to climate change, yet evidence in globally imperiled amphibians is lacking. Shifts in average population body size could indicate either plasticity in the growth response to changing climates through changes in allocation and energetics, or through selection for decreased size where energy is limiting. We compared historic and contemporary size measurements in 15 Plethodon species from 102 populations (9450 individuals) and found that six species exhibited significant reductions in body size over 55 years. Biophysical models, accounting for actual changes in moisture and air temperature over that period, showed a 7.1 ...


Swimming Against The Tide: Resilience Of A Riverine Turtle To Recurrent Extreme Environmental Events, Abigail M. Jergenson, David A. W. Miller, Lorin A. Neuman-Lee, Daniel A. Warner, Fredric J. Janzen Mar 2014

Swimming Against The Tide: Resilience Of A Riverine Turtle To Recurrent Extreme Environmental Events, Abigail M. Jergenson, David A. W. Miller, Lorin A. Neuman-Lee, Daniel A. Warner, Fredric J. Janzen

Ecology, Evolution and Organismal Biology Publications

Extreme environmental events (EEEs) are likely to exert deleterious effects on populations. From 1996 to 2012 we studied the nesting dynamics of a riverine population of painted turtles (Chrysemys picta) that experienced seven years with significantly definable spring floods. We used capture–mark–recapture methods to estimate the relationships between more than 5 m and more than 6 m flood events and population parameters. Contrary to expectations, flooding was not associated with annual differences in survival, recruitment or annual population growth rates of the adult female segment of the population. These findings suggest that female C. pictaexhibit resiliency to ...


Population Genetics Of Blanding’S Turtle (Emys Blandingii) In The Midwestern United States, Arun Sethuraman, Suzanne E. Mcgaugh, Morgan L. Becker, Christopher H. Chandler, James L. Christiansen, Sue Hayden, Andrea Leclere, Jennifer Monson-Miller, Erin M. Myers, Ryan T. Paitz, Jeanine M. Refsnider, Terry J. Vandewalle, Fredric J. Janzen Feb 2014

Population Genetics Of Blanding’S Turtle (Emys Blandingii) In The Midwestern United States, Arun Sethuraman, Suzanne E. Mcgaugh, Morgan L. Becker, Christopher H. Chandler, James L. Christiansen, Sue Hayden, Andrea Leclere, Jennifer Monson-Miller, Erin M. Myers, Ryan T. Paitz, Jeanine M. Refsnider, Terry J. Vandewalle, Fredric J. Janzen

Ecology, Evolution and Organismal Biology Publications

Blanding’s turtle (Emys blandingii) has declined substantially in North America due to anthropogenic activities, leaving populations smaller and increasingly fragmented spatially. We sampled 212 turtles to evaluate variation at eight microsatellite loci within and among 18 populations of E. blandingii across its primary range in the midwestern United States (Illinois, Iowa, Minnesota, and Nebraska). All loci and populations were highly polymorphic. Our analyses also detected considerable genetic structure within and among the sampled localities, and revealed ancestral gene flow of E. blandingii in this region north and east from an ancient refugium in the central Great Plains, concordant with ...


Trans-Gulf Of Mexico Loop Migration Of Tree Swallows Revealed By Solar Geolocation, David W. Bradley, Robert G. Clark, Peter O. Dunn, Andrew J. Laughlin, Caz M. Taylor, Carol M. Vleck, Linda A. Whittingham, David W. Winkler, D. Ryan Norris Jan 2014

Trans-Gulf Of Mexico Loop Migration Of Tree Swallows Revealed By Solar Geolocation, David W. Bradley, Robert G. Clark, Peter O. Dunn, Andrew J. Laughlin, Caz M. Taylor, Carol M. Vleck, Linda A. Whittingham, David W. Winkler, D. Ryan Norris

Ecology, Evolution and Organismal Biology Publications

One of the greatest feats of avian migration is the non-stop crossing of extensive areas of inhospitable habitat such as deserts and seas. Differences in spring and autumn migration routes have been reported in species that cross such barriers, and are thought to have evolved in response to seasonal variation in prevailing wind direction. We tested the hypothesis that migration routes vary seasonally with respect to the Gulf of Mexico in the tree swallow Tachycineta bicolor using solar geolocators attached and retrieved at 4 breeding sites in central North America. We found that 100 % of birds (n = 10) made a ...


Immobile And Mobile Life-History Stages Have Different Thermal Physiologies In A Lizard, Rory S. Telemeco Jan 2014

Immobile And Mobile Life-History Stages Have Different Thermal Physiologies In A Lizard, Rory S. Telemeco

Ecology, Evolution and Organismal Biology Publications

Temperature affects multiple aspects of an organism’s biology and thus defines a major axis of the fundamental niche. For ectotherms, variation in the thermal environment is particularly important because most of these taxa have a limited capacity to thermoregulate via metabolic heat production. While temperature affects all life-history stages, stages can differ in their ability to respond to the thermal environment. For example, in oviparous organisms, free-living adults can behaviorally thermoregulate, whereas developing embryos are at the mercy of the nest environment. These differences in the realized thermal environment should select for life-history stages to have different thermal tolerances ...


Exogenous Application Of Estradiol To Eggs Unexpectedly Induces Male Development In Two Turtle Species With Temperaturedependent Sex Determination, Daniel A. Warner, Elizabeth Addis, Wei-Guo Du, Thane Wibbels, Fredric J. Janzen Jan 2014

Exogenous Application Of Estradiol To Eggs Unexpectedly Induces Male Development In Two Turtle Species With Temperaturedependent Sex Determination, Daniel A. Warner, Elizabeth Addis, Wei-Guo Du, Thane Wibbels, Fredric J. Janzen

Ecology, Evolution and Organismal Biology Publications

Steroid hormones affect sex determination in a variety of vertebrates. The feminizing effects of exposure to estradiol and the masculinizing effects of aromatase inhibition during development are well established in a broad range of vertebrate taxa, but paradoxical findings are occasionally reported. Four independent experiments were conducted on two turtle species with temperature-dependent sex determination (Chrysemys picta and Chelydra serpentina) to quantify the effects of egg incubation temperature, estradiol, and an aromatase inhibitor on offspring sex ratios. As expected, the warmer incubation temperatures induced female development and the cooler temperatures produced primarily males. However, application of an aromatase inhibitor had ...


Telomere Length, Non-Breeding Habitat And Return Rate In Male American Redstarts, Frederic Angelier, Carol M. Vleck, Rebecca L. Holberton, Peter P. Marra Jan 2013

Telomere Length, Non-Breeding Habitat And Return Rate In Male American Redstarts, Frederic Angelier, Carol M. Vleck, Rebecca L. Holberton, Peter P. Marra

Ecology, Evolution and Organismal Biology Publications

  1. Telomeres are long repetitive noncoding sequences of DNA located at the ends of chromosomes. Recently, the study of telomere dynamics has been increasingly used to investigate ecological questions. However, little is currently known about the relationships that link environmental conditions, telomere dynamics and fitness in wild vertebrates.
  2. Using a small migratory bird (American redstart, Setophaga ruticilla), we investigated how telomere dynamics can be affected by non-breeding habitat quality and to what extent telomere length can predict the return rate of males.
  3. We show that telomeres shorten in most individuals over a 1-year period and, importantly, that telomeres of individuals wintering ...


Complex Interplay Of Body Condition, Life History, And Prevailing Environment Shapes Immune Defenses Of Garter Snakes In The Wild, Maria G. Palacios, Anne M. Bronikowski, Joan E. Cunnick Jan 2013

Complex Interplay Of Body Condition, Life History, And Prevailing Environment Shapes Immune Defenses Of Garter Snakes In The Wild, Maria G. Palacios, Anne M. Bronikowski, Joan E. Cunnick

Ecology, Evolution and Organismal Biology Publications

The immunocompetence “pace-of-life” hypothesis proposes that fast-living organisms should invest more in innate immune defenses and less in adaptive defenses compared to slow-living ones. We found some support for this hypothesis in two lifehistory ecotypes of the snake Thamnophis elegans; fast-living individuals show higher levels of innate immunity compared to slow-living ones. Here, we optimized a lymphocyte proliferation assay to assess the complementary prediction that slowliving snakes should in turn show stronger adaptive defenses. We also assessed the “environmental” hypothesis that predicts that slow-living snakes should show lower levels of immune defenses (both innate and adaptive) given the harsher environment ...


Behavioural Plasticity May Compensate For Climate Change In A Long-Lived Reptile With Temperature-Dependent Sex Determination, Jeanine M. Refsnider, Fredric J. Janzen Aug 2012

Behavioural Plasticity May Compensate For Climate Change In A Long-Lived Reptile With Temperature-Dependent Sex Determination, Jeanine M. Refsnider, Fredric J. Janzen

Ecology, Evolution and Organismal Biology Publications

How are organisms responding to climate change? The rapidity with which climate is changing suggests that, in species with long generation times, adaptive evolution may be too slow to keep pace with climate change, and that alternative mechanisms, such as behavioural plasticity, may be necessary for population persistence. Species with temperature-dependent sex determination may be particularly threatened by climate change, because altered temperatures could skew sex ratios. We experimentally tested nest-site choice in the long-lived turtle Chrysemys picta to determine whether nesting behaviour can compensate for potential skews in sex ratios caused by rapid climate change. We collected females from ...


Pleistocene And Ecological Effects On Continental-Scale Genetic Differentiation In The Bobcat (Lynx Rufus), Dawn M. Reding, Anne M. Bronikowski, Warren E. Johnson, William R. Clark Jun 2012

Pleistocene And Ecological Effects On Continental-Scale Genetic Differentiation In The Bobcat (Lynx Rufus), Dawn M. Reding, Anne M. Bronikowski, Warren E. Johnson, William R. Clark

Ecology, Evolution and Organismal Biology Publications

The potential for widespread, mobile species to exhibit genetic structure without clear geographic barriers is a topic of growing interest. Yet the patterns and mechanisms of structure—particularly over broad spatial scales—remain largely unexplored for these species. Bobcats occur across North America and possess many characteristics expected to promote gene flow. To test whether historical, topographic or ecological factors have influenced genetic differentiation in this species, we analysed 1 kb mtDNA sequence and 15 microsatellite loci from over 1700 samples collected across its range. The primary signature in both marker types involved a longitudinal cline with a sharp transition ...


Interrelations Among Immune Defense Indexes Reflect Major Components Of The Immune System In A Free-Living Vertebrate, Maria G. Palacios, Joan E. Cunnick, David W. Winkler, Carol M. Vleck Jan 2012

Interrelations Among Immune Defense Indexes Reflect Major Components Of The Immune System In A Free-Living Vertebrate, Maria G. Palacios, Joan E. Cunnick, David W. Winkler, Carol M. Vleck

Ecology, Evolution and Organismal Biology Publications

Understanding the relationships among immune components in free-living animals is a challenge in ecoimmunology, and it is important not only for selecting the immune assays to be used but also for more knowledgeable interpretation of results. In this study, we investigated the relationships among six immune defense indexes commonly used by ecoimmunologists and measured simultaneously in individual free-living tree swallows. Three main axes of variation in immune function were identified using a principal components analysis, representing variation in T-cell, B-cell, and innate immunity. Measures within each axis tended to be positively correlated among individuals, while measures in different axes were ...


Turtles: The Animal Answer Guide, Fredric J. Janzen Dec 2011

Turtles: The Animal Answer Guide, Fredric J. Janzen

Ecology, Evolution and Organismal Biology Publications

Turtles are among the most universally adored organisms. They exhibit an instantly recognizable morphology, yet lead lives that are cryptic to the casual observer, thus questions naturally surface regarding all sorts of aspects of their biology and history. In the absence of informed experience, mythic explanations have arisen and even become entrenched culturally, often doing no favor to the turtles or to turtle biologists who must combat such nonsense on behalf of the animals. Into this informational void appears this volume prepared by the expert authors, with the assistance of many knowledgeable colleagues.


Plasma Testosterone Concentrations In Adult Tree Swallows During The Breeding Season, Molly Staley, Carol M. Vleck, David Vleck Sep 2011

Plasma Testosterone Concentrations In Adult Tree Swallows During The Breeding Season, Molly Staley, Carol M. Vleck, David Vleck

Ecology, Evolution and Organismal Biology Publications

We studied seasonal profiles of circulating testosterone concentrations among male and female adult Tree Swallows (Tachycineta bicolor) breeding in nest-box colonies near Ames, Iowa, USA. Mean plasma testosterone in males was elevated during nest establishment (0.63 ± 0.86 ng/ml) and incubation stages (0.28 ± 0.26 ng/ml), and was significantly lower after hatching (0.03 ± 0.05 ng/ml) when males began provisioning nestlings. Male swallows do not incubate and high testosterone during the incubation stage may facilitate pursuit of extra-pair matings. Female testosterone concentrations were an order of magnitude lower than those of males (nest establishment ...


Stochastic Population Dynamics In Populations Of Western Terrestrial Garter Snakes With Divergent Life Histories, David A. Miller, William R. Clark, Stevan J. Arnold, Anne M. Bronikowski Aug 2011

Stochastic Population Dynamics In Populations Of Western Terrestrial Garter Snakes With Divergent Life Histories, David A. Miller, William R. Clark, Stevan J. Arnold, Anne M. Bronikowski

Ecology, Evolution and Organismal Biology Publications

Comparative evaluations of population dynamics in species with temporal and spatial variation in life-history traits are rare because they require long-term demographic time series from multiple populations. We present such an analysis using demographic data collected during the interval 1978–1996 for six populations of western terrestrial garter snakes (Thamnophis elegans) from two evolutionarily divergent ecotypes. Three replicate populations from a slow-living ecotype, found in mountain meadows of northeastern California, were characterized by individuals that develop slowly, mature late, reproduce infrequently with small reproductive effort, and live longer than individuals of three populations of a fast-living ecotype found at lakeshore ...


Consequences Of Immune System Aging In Nature: A Study Of Immunosenescence Costs In Free-Living Tree Swallows, Maria G. Palacios, David W. Winkler, Kirk C. Klasing, Dennis Hasselquist, Carol M. Vleck Apr 2011

Consequences Of Immune System Aging In Nature: A Study Of Immunosenescence Costs In Free-Living Tree Swallows, Maria G. Palacios, David W. Winkler, Kirk C. Klasing, Dennis Hasselquist, Carol M. Vleck

Ecology, Evolution and Organismal Biology Publications

Immunosenescence, the aging of the immune system, is well documented in humans and laboratory models and is known to increase infection risk, morbidity, and mortality among the old. Immunosenescence patterns have recently been unveiled in various free-living populations, but their consequences in the wild have not been explored. We investigated the consequences of immunosenescence in free-living Tree Swallows Tachycineta bicolorthrough a field experiment simulating a bacterial infection (challenge with lipopolysaccharide, LPS) in females of different ages during the nestling rearing period. We assessed behavioral and physiological responses of females, as well as growth and quality of their offspring, to ...


Low Demographic Variability In Wild Primate Populations: Fitness Impacts Of Variation, Covariation, And Serial Correlation In Vital Rates, William F. Morris, Jeanne Altmann, Diane K. Brockman, Marina Cords, Linda M. Fedigan, Anne E. Pusey, Tara S. Stoinski, Anne M. Bronikowski, Susan C. Alberts, Karen B. Strier Jan 2011

Low Demographic Variability In Wild Primate Populations: Fitness Impacts Of Variation, Covariation, And Serial Correlation In Vital Rates, William F. Morris, Jeanne Altmann, Diane K. Brockman, Marina Cords, Linda M. Fedigan, Anne E. Pusey, Tara S. Stoinski, Anne M. Bronikowski, Susan C. Alberts, Karen B. Strier

Ecology, Evolution and Organismal Biology Publications

In a stochastic environment, long-term fitness can be influenced by variation, covariation, and serial correlation in vital rates (survival and fertility). Yet no study of an animal population has parsed the contributions of these three aspects of variability to long-term fitness. We do so using a unique database that includes complete life-history information for wild-living individuals of seven primate species that have been the subjects of long-term (22–45 years) behavioral studies. Overall, the estimated levels of vital rate variation had only minor effects on long-term fitness, and the effects of vital rate covariation and serial correlation were even weaker ...


A Proposal To Sequence The Genome Of A Garter Snake (Thamnophis Sirtalis), Todd A. Castoe, Anne M. Bronikowski, Edmund D. Brodie Iii, Scott V. Edwards, Michael E. Pfrender, Michael D. Shapiro, David D. Pollock, Wesley C. Warren Jan 2011

A Proposal To Sequence The Genome Of A Garter Snake (Thamnophis Sirtalis), Todd A. Castoe, Anne M. Bronikowski, Edmund D. Brodie Iii, Scott V. Edwards, Michael E. Pfrender, Michael D. Shapiro, David D. Pollock, Wesley C. Warren

Ecology, Evolution and Organismal Biology Publications

Here we develop an argument in support of sequencing a garter snake (Thamnophis sirtalis) genome, and outline a plan to accomplish this. This snake is a common, widespread, nonvenomous North American species that has served as a model for diverse studies in evolutionary biology, physiology, genomics, behavior and coevolution. The anole lizard is currently the only genome sequence available for a non-avian reptile. Thus, the garter snake at this time would be the first available snake genome sequence and as such would provide much needed comparative representation of non-avian reptilian genomes, and would also allow critical new insights for vertebrate ...


Sequencing The Genome Of The Burmese Python (Python Molurus Bivittatus) As A Model For Studying Extreme Adaptations In Snakes, Todd A. Castoe, Ap Jason De Koning, Kathryn G. Hall, Ken D. Yokoyama, Wanjun Gu, Eric N. Smith, Cédric Feschotte, Peter Uetz, David A. Ray, Jason Dobry, Robert Bogden, Stephen P. Mackessy, Anne M. Bronikowski, Wesley C. Warren, Stephen M. Secor, David D. Pollock Jan 2011

Sequencing The Genome Of The Burmese Python (Python Molurus Bivittatus) As A Model For Studying Extreme Adaptations In Snakes, Todd A. Castoe, Ap Jason De Koning, Kathryn G. Hall, Ken D. Yokoyama, Wanjun Gu, Eric N. Smith, Cédric Feschotte, Peter Uetz, David A. Ray, Jason Dobry, Robert Bogden, Stephen P. Mackessy, Anne M. Bronikowski, Wesley C. Warren, Stephen M. Secor, David D. Pollock

Ecology, Evolution and Organismal Biology Publications

The Consortium for Snake Genomics is in the process of sequencing the genome and creating transcriptomic resources for the Burmese python. Here, we describe how this will be done, what analyses this work will include, and provide a timeline.


Ontogenetic Convergence And Evolution Of Foot Morphology In European Cave Salamanders (Family: Plethodontidae), Dean C. Adams, Annamaria Nistri Jul 2010

Ontogenetic Convergence And Evolution Of Foot Morphology In European Cave Salamanders (Family: Plethodontidae), Dean C. Adams, Annamaria Nistri

Ecology, Evolution and Organismal Biology Publications

A major goal in evolutionary biology is to understand the evolution of phenotypic diversity. Both natural and sexual selection play a large role in generating phenotypic adaptations, with biomechanical requirements and developmental mechanisms mediating patterns of phenotypic evolution. For many traits, the relative importance of selective and developmental components remains understudied. We investigated ontogenetic trajectories of foot morphology in the eight species of European plethodontid cave salamander to test the hypothesis that adult foot morphology was adapted for climbing. Using geometric morphometrics and other approaches, we found that developmental patterns in five species displayed little morphological change during growth (isometry ...


Parallel Evolution Of Character Displacement Driven By Competitive Selection In Terrestrial Salamanders, Dean C. Adams Mar 2010

Parallel Evolution Of Character Displacement Driven By Competitive Selection In Terrestrial Salamanders, Dean C. Adams

Ecology, Evolution and Organismal Biology Publications

Parallel evolution can occur when common environmental factors exert similar selective forces on morphological variation in populations in different geographic localities. Competition can also generate morphological shifts, and if competing species co-occur in multiple geographic regions, then repeated instances of competitively-driven morphological divergence (character displacement) can occur. Despite the importance of character displacement for inferring the role of selection in morphological evolution however, replicated instances of sympatric morphological divergence are understudied. I tested the hypothesis that interspecific competition generated patterns of parallel morphological divergence in multiple geographic locations where two competing salamander species, Plethodon jordani and P. teyahalee, come into ...


Evolution Of Senescence In Nature: Physiological Evolution In Populations Of Garter Snake With Divergent Life Histories, Kylie A. Robert, Anne M. Bronikowski Feb 2010

Evolution Of Senescence In Nature: Physiological Evolution In Populations Of Garter Snake With Divergent Life Histories, Kylie A. Robert, Anne M. Bronikowski

Ecology, Evolution and Organismal Biology Publications

Evolutionary theories of aging are linked to life-history theory in that age-specific schedules of reproduction and survival determine the trajectory of age-specific mutation/selection balances across the life span and thus the rate of senescence. This is predicted to manifest at the organismal level in the evolution of energy allocation strategies of investing in somatic maintenance and robust stress responses in less hazardous envirnments in exchange for energy spent on growth and reproduction. Here we report experiments from long-studied populations of western terrestrial garter snakes (Thamnophis elegans) that reside in low and high extrinsic mortality environments, with evolved long and ...


A Garter Snake Transcriptome: Pyrosequencing, De Novo Assembly, And Sex-Specific Differences, Tonia S. Schwartz, Hongseok Tae, Youngik Yang, Keithanne Mockaitis, John L. Van Hemert, Stephen R. Proulx, Jeong-Hyeon Choi, Anne M. Bronikowski Jan 2010

A Garter Snake Transcriptome: Pyrosequencing, De Novo Assembly, And Sex-Specific Differences, Tonia S. Schwartz, Hongseok Tae, Youngik Yang, Keithanne Mockaitis, John L. Van Hemert, Stephen R. Proulx, Jeong-Hyeon Choi, Anne M. Bronikowski

Ecology, Evolution and Organismal Biology Publications

Background

The reptiles, characterized by both diversity and unique evolutionary adaptations, provide a comprehensive system for comparative studies of metabolism, physiology, and development. However, molecular resources for ectothermic reptiles are severely limited, hampering our ability to study the genetic basis for many evolutionarily important traits such as metabolic plasticity, extreme longevity, limblessness, venom, and freeze tolerance. Here we use massively parallel sequencing (454 GS-FLX Titanium) to generate a transcriptome of the western terrestrial garter snake (Thamnophis elegans) with two goals in mind. First, we develop a molecular resource for an ectothermic reptile; and second, we use these sex-specific transcriptomes to ...


Aging And Its Demographic Measurement, Anne M. Bronikowski, Thomas Flatt Jan 2010

Aging And Its Demographic Measurement, Anne M. Bronikowski, Thomas Flatt

Ecology, Evolution and Organismal Biology Publications

Aging is an inevitable fact of life. But as life span increases, do aging processes slow down? Here, we introduce how to measure life span, aging rate, and frailty, in cohorts and populations.


Individual Variation In Baseline And Stress-Induced Corticosterone And Prolactin Levels Predicts Parental Effort By Nesting Mourning Doves, David A. Miller, Carol M. Vleck, David L. Otis Oct 2009

Individual Variation In Baseline And Stress-Induced Corticosterone And Prolactin Levels Predicts Parental Effort By Nesting Mourning Doves, David A. Miller, Carol M. Vleck, David L. Otis

Ecology, Evolution and Organismal Biology Publications

Endocrine systems have an important mechanistic role in structuring life-history trade-offs. During breeding, individual variation in prolactin (PRL) and corticosterone (CORT) levels affects behavioral and physiological processes that drive trade-offs between reproduction and self-maintenance. We examined patterns in baseline (BL) and stress induced (SI; level following a standard capture-restraint protocol) levels of PRL and CORT for breeding mourning doves (Zenaida macroura). We determined whether the relationship of adult condition and parental effort to hormone levels in wild birds was consistent with life-history predictions. Both BL PRL and BL CORT level in adults were positively related to nestling weight at early ...


Evolutionary Ecology Of Endocrine-Mediated Life-History Variation In The Garter Snake Thamnophis Elegans, Amanda M. Sparkman, Carol M. Vleck, Anne M. Bronikowski Mar 2009

Evolutionary Ecology Of Endocrine-Mediated Life-History Variation In The Garter Snake Thamnophis Elegans, Amanda M. Sparkman, Carol M. Vleck, Anne M. Bronikowski

Ecology, Evolution and Organismal Biology Publications

The endocrine system plays an integral role in the regulation of key life-history traits. Insulin-like growth factor-1 (IGF-1) is a hormone that promotes growth and reproduction, and it has been implicated in the reduction of lifespan. IGF-1 is also capable of responding plastically to environmental stimuli such as resource availability and temperature. Thus pleiotropic control of life-history traits by IGF-1 could provide a mechanism for the evolution of correlated life-history traits in a new or changing environment. An ideal system in which to investigate the role of IGF-1 in life-history evolution exists in two ecotypes of the garter snake Thamnophis ...