Biology subjects

Wunder, M. B.

Publications and source records attributed to Wunder, M. B..

6 recordsLinked to original sources

bioRxiv2026

Stage-specific habitat use of the Mountain Plover in Colorado

Habitat structure, food availability, and predation risk have spatiotemporal variation on the landscape that creates tradeoffs between risk and rewards for animals as they use habitat. These tradeoffs are associated with survival consequences and can vary by life or breeding stage, but stage-specific shifts in these relationships are often not considered in studies of habitat use and survival. We investigated habitat use for nests and broods in the Mountain plover as an example of a ground-nesting species with precocial, mobile young to explore breeding stage-specific responses to vegetation structure, food availability, and predation risk. We located and monitored nests and broods at two study sites in Colorado occupied by geographically separated breeding populations of plovers. We quantified the three covariate categories across standardized site-wide grids in 2021 and 2022. We employed a resource selection analysis to evaluate 10 a priori working hypotheses for how environmental covariates may influence the habitat used by plovers for nesting and brood-rearing. Model comparison results suggest that habitat use relative to availability is best explained by a linear relationship with vegetation structure while conditioning on breeding stage and site, with no effect of food availability or predation risk detected in our dataset. Specifically, probability of use for both nest and brood sites was highest in areas with taller vegetation, contrary to previous research about nest site selection. These unexpected results may be due to the unbalanced sample sizes of the two sites, as previous separate studies have shown opposing habitat use strategies, or due to the coarseness of our covariate data. Regardless of limitations, these results emphasize the importance of investigating stage-specific and potentially site-specific shifts in habitat use patterns for species with precocial young.

ecology↗

bioRxiv2023

Seasonal migration alters energetic trade-off optimization and shapes life history.

Trade-offs between current and future reproduction manifest as a set of co-varying life history and metabolic traits, collectively referred to as "pace of life" (POL). Seasonal migration modulates realized environmental dynamics and putatively affects realized POL, however, the mechanisms by which migratory behavior shapes POL remain unclear. We explored how migratory behavior interacts with environmental and metabolic dynamics to shape POL. Using an individual based model of movement and metabolism we compared fitness-optimized trade-offs among migration strategies. We found annual experienced seasonality and migration distance primarily drove POL differentiation through developmental and migration phenology trade-offs. Similarly, our analysis of empirically-estimated metabolic data from 265 bird species suggested seasonal niche conservatism and migration distance interact to drive POL. We show multiple viable life history strategies are conducive to a migratory lifestyle. Overall, our findings suggest metabolism mediates complex interactions between behavior, environment, and life history. Authorship statementAKP and SWY contributed equally to this work. AKP and SWY conceived the project, designed the model, performed analyses, and drafted the manuscript with support from MBW. Simulation and optimization model code written by AKP with input from SWY and MBW. Empirical data analysis and code lead by SWY with input from AKP and MBW. All authors contributed critical input to the manuscript. Data accessibility statementAll R code for models and analyses are available at https://doi.org/10.5281/zenodo.10145976 and https://github.com/allipierce/Pierce_et_al_2023_MigrationPOL. The empirically derived data used in this work are all publicly available. DEB data are available from the Add-My-Pet portal at https://www.bio.vu.nl/thb/deb/deblab/add_my_pet/. Geographic range data are available from BirdLife International at http://datazone.birdlife.org/species/requestdis. Niche dissimilarity data came from https://doi.org/10.1111/geb.13722 and phylogeny data are available from VertLife at http://vertlife.org/data/.

evolutionary biology↗

bioRxiv2023

Geographic distribution of feather δ34S in Europe

Geographic distribution models of environmental stable isotopes (so called isoscapes) are widely employed in animal ecology, wildlife forensics and conservation. However, the application of isoscapes is limited to elements and regions for which the spatial patterns have been estimated. Here, we focused on the ubiquitous yet less commonly used stable sulfur isotopes ({delta}34S). To predict the European{delta} 34S isoscape, we used 242 feather samples from Eurasian Reed Warbler (Acrocephalus scirpaceus) formed at 69 European wetland sites. We quantified the relationships between sample{delta} 34S and environmental covariates using a random forest regression model and applied the model to predict the geographic distribution of{delta} 34S. We also quantified within-site variation in{delta} 34S and complementarity with other isotopes on both individual and isoscape levels. The predicted feather{delta} 34S isoscape shows only slight differences between the central and southern parts of Europe while the coastal regions were most enriched in 34S. The most important covariates of{delta} 34S were distance to coastline, surface elevation and atmospheric concentrations of SO2 gases. The absence of a systematic spatial pattern impedes the application of the{delta} 34S isoscape but high complementarity with other isoscapes advocates the combination of multiple isoscapes to increase precision of animal tracing. Feather{delta} 34S compositions showed considerable within-site variation with highest values in inland parts of Europe, likely attributed to wetland anaerobic conditions and redox sensitivity of sulfur. The complex European geography and topography as well as using{delta} 34S samples from wetlands may contribute to the absence of a systematic spatial gradient of{delta} 34S values in Europe. We thus encourage future studies to focus on the geographic distribution of{delta} 34S using tissues from diverse taxa collected in various habitats over large land masses in the world (i.e., Africa, South America or East Asia). Open Research statementSample metadata are stored and available for reuse in the AviSample Network database (https://avisample.net/: AS00001-AS00117; Brlik et al. 2022b). The information on the isotopic composition and geographic origin of feather samples used to produce the{delta} 34S isoscape, predicted feather{delta} 34S,{delta} 2H and{delta} 13C isoscapes are publicly available from the Zenodo data repository at https://doi.org/10.5281/zenodo.7315567 (Brlik et al. 2022c).

ecology↗

bioRxiv2022

Genetic and ecological drivers of molt in a migratory bird

The ability of animals to sync the timing and location of molting (the replacement of hair, skin, exoskeletons or feathers) with peaks in resource availability has important implications for their ecology and evolution. In migratory birds, the timing and location of pre-migratory feather molting, a period when feathers are shed and replaced with newer, more aerodynamic feathers, can vary within and between species. While hypotheses to explain the evolution of intraspecific variation in the timing and location of molt have been proposed, little is known about the genetic basis of this trait or the specific environmental drivers that may result in natural selection for distinct molting phenotypes. Here we take advantage of intraspecific variation in the timing and location of molt in the iconic songbird, the Painted Bunting (Passerina ciris) to investigate the genetic and ecological drivers of distinct molting phenotypes. Specifically, we use genome-wide genetic sequencing in combination with stable isotope analysis to determine population genetic structure and molting phenotype across thirteen breeding sites. We then use genome-wide association analysis (GWAS) to identify a suite of genes associated with molting and pair this with gene-environment association analysis (GEA) to investigate potential environmental drivers of genetic variation in this trait. Associations between genetic variation in molt-linked genes and the environment are further tested via targeted SNP genotyping in 25 additional breeding populations across the range. Together, our integrative analysis suggests that molting is in part regulated by genes linked to feather development and structure (GLI2 and CSPG4) and that genetic variation in these genes is associated with seasonal variation in precipitation and aridity. Overall, this work provides important insights into the genetic basis and potential selective forces behind phenotypic variation in what is arguably one of the most important fitness-linked traits in a migratory bird.

ecology↗

bioRxiv2021

A multiple hypotheses framework to study movement ecology and diet in a migratory songbird

Whether and how migratory organisms exhibit inter-individual behavioral and/or physiological variation across movement strategies remains an open question. The Dark-eyed Junco (Junco hyemalis) is a migratory songbird known for its intra-species variation displayed in relation to morphology, song repertoires, and migration. Thus, studies focusing on juncos can reveal how migratory strategy may covary with other individual-scale factors and, therefore, identify the selective forces driving intra-species variations throughout its distribution. We used Dark-eyed Junco hydrogen stable isotope feather values (delta2H) and implemented a Bayesian framework to infer the breeding and molting origin of migratory juncos captured on their winter grounds in Oklahoma, United States (U.S.). We modeled the distribution of feather hydrogen stable isotope values as a function of five morphological variables including body mass and fat deposition measured in Oklahoma during the winter. We then investigated the trade-off between longer and more energetically costly migration strategies in relation to diet preferences through carbon (delta13C) and nitrogen (delta15N) stable isotope analysis from feather values. Dark-eyed Juncos wintering in south central U.S. likely originate from multiple breeding populations in northern U.S. and Canada. Body condition at the wintering ground (e.g., mass) had no effect on feather hydrogen stable isotope abundance. However, we found a positive correlation between nitrogen and hydrogen stable isotopes, suggesting that a trophic level shift towards insect consumption might occur in individuals migrating from southern latitudes. Increased insect-derived protein consumption might be explained by reduced fatty-acid reserves necessary to complete a shorter migratory journey.

ecology↗

bioRxiv2019

Migratory divides coincide with species barriers across replicated avian hybrid zones above the Tibetan Plateau

Migratory divides are proposed to be catalysts for speciation across a diversity of taxa. However, the relative contribution of migratory behavior to reproductive isolation is difficult to test. Comparing reproductive isolation in hybrid zones with and without migratory divides offers a rare opportunity to directly examine the contribution of divergent migratory behavior to reproductive barriers. We show that across replicate sampling transects of two pairs of barn swallow (Hirundo rustica) subspecies, strong reproductive isolation coincided with an apparent migratory divide spanning 20 degrees of latitude. A third subspecies pair exhibited no evidence for a migratory divide and hybridized extensively. Within migratory divides, migratory phenotype was associated with assortative mating, implicating a central contribution of divergent migratory behavior to reproductive barriers. The remarkable geographic coincidence between migratory divides and genetic breaks supports a longstanding hypothesis that the Tibetan Plateau is a substantial barrier contributing to the diversity of Siberian avifauna.

evolutionary biology↗