18 Works

Data from: A hybrid phylogenetic–phylogenomic approach for species tree estimation in African Agama lizards with applications to biogeography, character evolution, and diversification

Adam D. Leaché, Philipp Wagner, Charles W. Linkem, Wolfgang Böhme, Theodore J. Papenfuss, Rebecca A. Chong, Brian R. Lavin, Aaron M. Bauer, Stuart V. Nielsen, Eli Greenbaum, Mark-Oliver Rödel, Andreas Schmitz, Matthew LeBreton, Ivan Ineich, Laurent Chirio, Caleb Ofori-Boateng, Edem A. Eniang, Sherif Baha El Din, Alan R. Lemmon & Frank T. Burbrink
Africa is renowned for its biodiversity and endemicity, yet little is known about the factors shaping them across the continent. African Agama lizards (45 species) have a pan-continental distribution, making them an ideal model for investigating biogeography. Many species have evolved conspicuous sexually dimorphic traits, including extravagant breeding coloration in adult males, large adult male body sizes, and variability in social systems among colorful versus drab species. We present a comprehensive time-calibrated species tree for...

Birth timing after the long feeding migration in northern elephant seals

Richard Condit, Roxanne S. Beltran, Patrick W. Robinson, Daniel E. Crocker & Daniel P. Costa
A prominent phase of the annual cyle in migratory animals is the transition between migration and reproduction. The transition is a small part of the annual cycle, but details of its timing deserve attention. From a distant location, animals must initiate a long migration so that they arrive at the breeding ground on a precise schedule. Here we take advantage of a sample of female northern elephant seals that were tracked by satellite during their...

Mitonuclear mismatch alters performance and reproductive success in naturally-introgressed populations of a montane leaf beetle

Nathan Rank, Nathan E Rank, Patrick Mardulyn, Sarah J Heidl, Kevin T Roberts, Nicolas A Zavala, John T Smiley & Elizabeth P Dahlhoff
Coordination between nuclear and mitochondrial genomes is critical to metabolic processes underlying animals' ability to adapt to local environments, yet consequences of mitonuclear interactions have rarely been investigated in populations where individuals with divergent mitochondrial and nuclear genomes naturally interbreed. Genetic variation in the leaf beetle Chrysomela aeneicollis was assessed along a latitudinal thermal gradient in California's Sierra Nevada. Variation at mitochondrial cytochrome oxidase II (COII) and the nuclear gene phosphoglucose isomerase (PGI) shows concordance...

Data from: Long-term and interactive effects of different mammalian consumers on growth, survival and recruitment of dominant tree species

J. Hall Cushman, Vanessa Dodge & Valerie Eviner
Throughout the world, numerous tree species are reported to be in decline, either due to increased mortality of established trees or reduced recruitment. The situation appears especially acute for oaks, which are dominant features of many landscapes in the northern hemisphere. Although numerous factors have been hypothesized to explain reductions in tree performance, vertebrate herbivores and granivores may serve as important drivers of these changes. Here, using data from 8- and 14-year-old exclosure experiments, we...

Weights of northern elephant seal weanlings from Año Nuevo Reserve

Patrick Robinson, Daniel Costa, Richard Condit, Patricia Morris, Joanne Reiter, Daniel Crocker, Roxanne Beltran & Burney Le Beouf
Long-term observations of foraging success at the population scale are key to understanding demographic and ecological patterns. Northern elephant seals, Mirounga angustirostris, are capital breeders and the resources delivered to the pup during the 4-week lactation period are related to both the past foraging success of the mother and the future survival of the pup post-weaning. We collected weight and basic morphometric data from more than 7,000 recently weaned elephant seals at the Año Nuevo...

Data from: Oxidative stress is a potential cost of breeding in male and female northern elephant seals.

Jeffrey T. Sharick, Jose P. Vazquez-Medina, Rudy M. Ortiz & Daniel E. Crocker
1.The trade-off between current reproductive effort and survival is a key concept of life history theory. A variety of studies support the existence of this trade-off but the underlying physiological mechanisms are not well-understood. Oxidative stress has been proposed as a potential mechanism underlying the observed inverse relationship between reproductive investment and lifespan. Prolonged fasting is associated with oxidative stress including increases in the production of reactive oxygen species, oxidative damage and inflammation. 2.Northern elephant...

Data from: Lactation and resource limitation affect stress responses, thyroid hormones, immune function and antioxidant capacity of sea otters (Enhydra lutris)

Sarah M. Chinn, Daniel H. Monson, M. Tim Tinker, Michelle M. Staedler & Daniel E. Crocker
1. Lactation is the most energetically demanding stage of reproduction in female mammals. Increased energetic allocation toward current reproduction may result in fitness costs, though the mechanisms underlying these trade-offs are not well understood. Trade-offs during lactation may include reduced energetic allocation to cellular maintenance, immune response and survival, and may be influenced by resource limitation. 2. As the smallest marine mammal, sea otters (Enhydra lutris) have the highest mass-specific metabolic rate necessitating substantial energetic...

Data from: Getting chased up the mountain- high elevation may limit performance and fitness characters in a montane insect

Elizabeth P. Dahlhoff, Victoria C. Dahlhoff, Corinne A. Grainger, Nicolas A. Zavala, Dami Otepola-Bello, Brynn A. Sargent, Kevin T. Roberts, Sarah J. Heidl, John T. Smiley & Nathan E. Rank
1. Climate change is expected to shift species distributions as populations grow in favorable habitats and decline in harsh ones. Montane animals escape warming conditions at low elevation by moving upslope, but may be physiologically constrained by conditions there. Effects of elevation were studied for montane populations of the leaf beetle Chrysomela aeneicollis, where allele frequencies at nuclear genes and the mitochondrion vary along latitudinal and altitudinal gradients. 2. A population presence survey conducted along...

Data from: Chromosomes tell half of the story: the correlation between karyotype rearrangements and genetic diversity in sedges, a group with holocentric chromosomes

Andrew Hipp, Paul Rothrock, Richard Whitkus & Jaime Weber
Chromosome rearrangements may affect the rate and patterns of gene flow within species, through reduced fitness of structural heterozygotes or by reducing recombination rates in rearranged areas of the genome. While the effects of chromosome rearrangements on gene flow have been studied in a wide range of organisms with monocentric chromosomes, the effects of rearrangements in holocentric chromosomes—chromosomes in which centromeric activity is distributed along the length of the chromosome—have not. We collected chromosome number...

Data from: Foraging and fasting can influence contaminant concentrations in animals: an example with mercury contamination in a free-ranging marine mammal

Sarah H. Peterson, Joshua T. Ackerman, Daniel E. Crocker & Daniel P. Costa
Large fluctuations in animal body mass in relation to life-history events can influence contaminant concentrations and toxicological risk. We quantified mercury concentrations in adult northern elephant seals (Mirounga angustirostris) before and after lengthy at sea foraging trips (n = 89) or fasting periods on land (n = 27), and showed that mercury concentrations in blood and muscle changed in response to these events. The highest blood mercury concentrations were observed after the breeding fast, whereas...

Data from: Whiskers provide time-series of toxic and essential trace elements, Se:Hg molar ratios, and stable isotope values of an apex Antarctic predator, the leopard seal

Patrick Charapata, Casey Clark, Nathan Miller, Sarah Kienle, Daniel Costa, Michael Goebel, Heather Gunn, Emily Sperou, Shane Kanatous, Daniel Crocker, Renato Borras-Chavez & Stephen Trumble
In an era of rapid environmental change and increasing human presence, researchers need efficient tools for tracking contaminants to monitor the health of Antarctic flora and fauna. Here, we examined the utility of leopard seal whiskers as a biomonitoring tool that reconstructs time-series of significant ecological and physiological biomarkers. Leopard seals (Hydrurga leptonyx) are a sentinel species in the Western Antarctic Peninsula due to their apex predator status and top-down effects on several Antarctic species....

Data from: Body reserves influence allocation to immune responses in capital breeding female northern elephant seals

Hannah E. Peck, Daniel P. Costa & Daniel E. Crocker
Mounting an immune response requires substantial energy. Ecological immunology theory predicts allocation trade-offs between reproductive effort and immune responses under conditions of energy limitation. Little is known about the impact of capital breeding strategies on energy allocation to immune function in mammals. Northern elephant seals (NES) forage in the marine environment, breed in dense terrestrial colonies and exhibit high rates of energy expenditure for lactation while fasting. Body reserves strongly influence reproductive effort and lactation...

Data from: Cascading effects of mammalian herbivores on ground-dwelling arthropods: variable responses across arthropod groups, habitats and years

Eric M. Cecil, Marko J. Spasojevic & J. Hall Cushman
1. Large mammalian herbivores are well known to shape the structure and function of ecosystems worldwide and these effects can in turn cascade through systems to indirectly influence other animal species. A wealth of studies have explored the effects of large mammals on arthropods, but to date they have reported such widely varying results that generalizations have been elusive. Three factors are likely drivers of this variability: the widely varying life-history characteristics of different arthropod...

Snow modulates winter energy use and cold exposure across an elevation gradient in a montane ectotherm

Kevin Roberts, Nathan Rank, Elizabeth Dahlhoff, Jonathon Stillman & Caroline Williams
Snow insulates the soil from air temperature, decreasing winter cold stress and altering energy use for organisms that overwinter in the soil. As climate change alters snowpack and air temperatures, it is critical to account for the role of snow in modulating vulnerability to winter climate change. Along elevational gradients in snowy mountains, snow cover increases but air temperature decreases, and it is unknown how these opposing gradients impact performance and fitness of organisms overwintering...

Data from: Indirect effects of a large mammalian herbivore on small mammal populations: context-dependent variation across habitat types, mammal species and seasons

Taylor D. Ellis & J. Hall Cushman
Multiple consumer species frequently co-occur in the same landscape and, through effects on surrounding environments, can interact in direct and indirect ways. These interactions can vary in occurrence and importance, and focusing on this variation is critical for understanding the dynamics of interactions among consumers. Large mammalian herbivores are important engineers of ecosystems worldwide, have substantial impacts on vegetation and can indirectly affect small-mammal populations. However, the degree to which such indirect effects vary within...

Data from: Density-dependent effects on reproductive output in a capital breeding carnivore, the northern elephant seal (Mirounga angustirostris)

Daniel Costa, Rachel Holser, Daniel Crocker, Patrick Robinson, Gitte McDonald, Melinda Fowler, Jason Hassrick, Luis Hückstädt, Sarah Peterson, Samantha Simmons & Theresa Keates
All organisms face resource limitations that will ultimately restrict population growth, but the controlling mechanisms vary across ecosystems, taxa, and reproductive strategies. Using four decades of data, we examine how variation in the environment and population density affect reproductive outcomes in a capital-breeding carnivore, the northern elephant seal (Mirounga angustirostris). This species provides a unique opportunity to examine the relative importance of resource acquisition and density-dependence on breeding success. Capital breeders accrue resources over large...

Improving landscape-scale productivity estimates by integrating trait-based models and remotely-sensed foliar-trait and canopy-structural data

Daniel Wieczynski, Sandra Diaz, Sandra Duran, Nikolaos Fyllas, Norma Salinas, Roberta Martin, Alexander Shenkin, Miles Silman, Gregory Asner, Lisa Bentley, Yadvinder Malhi, Brian Enquist & Van Savage
Assessing the impacts of anthropogenic degradation and climate change on global carbon cycling is hindered by a lack of clear, flexible, and easy-to-use productivity models along with scarce trait and productivity data for parameterizing and testing those models. We provide a simple solution: a mechanistic framework (RS-CFM) that combines remotely-sensed foliar-trait and canopy-structural data with trait-based metabolic theory to efficiently map productivity at large spatial scales. We test this framework by quantifying net primary productivity...

Foraging strategies and lifetime fitness in northern elephant seals

Daniel Costa, Roxanne Beltran, Richard Condit, Patrick Robinson, Daniel Crocker & Chandra Goetsch
We collected 25 years of demographic, foraging route, diving, and diet data from northern elephant seals (Mirounga angustirostris) to determine the influence of behavioral strategies and mass gain during 8-month foraging trips on reproduction, survival, and lifetime reproductive success.

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Resource Types

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Affiliations

  • Sonoma State University
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