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Full-Text Articles in Ecology and Evolutionary Biology
Ecological Niches, Species Distributions, And Biogeographic Processes In Rodents On Neotropical Sky Islands, Mariano Soley
Ecological Niches, Species Distributions, And Biogeographic Processes In Rodents On Neotropical Sky Islands, Mariano Soley
Dissertations, Theses, and Capstone Projects
This dissertation focused on the methodological and theoretical improvement of correlative ecological niche models (ENMs) to better understand the processes governing species distributions and associated evolutionary divergence in rodents inhabiting mesic conditions in the Neotropics. Focusing on a widespread rodent from northern South America (Heteromys anomalus), in the first chapter I proposed and tested a methodological approach to surmount the challenge of incorporating environmental information from the margins of species geographic ranges into ENMs. In so doing, I argue how populations that exist on the borders of species' local ranges (spatial margins) can lead to exaggerated estimates of their niches …
Foraging Ecology Of Shorebirds At A Stopover Site: Niche Dynamics, Aggression And Resource Use In Delaware Bay, Ivana Novcic
Foraging Ecology Of Shorebirds At A Stopover Site: Niche Dynamics, Aggression And Resource Use In Delaware Bay, Ivana Novcic
Dissertations, Theses, and Capstone Projects
Classical ecological theory predicts that generally similar species ought to partition resources in order to minimize competition amongst themselves. This basic idea becomes complex when one is dealing with species that migrate over thousands of miles and forage in a broad diversity of habitats and geographical locations. I studied a suite of migratory sandpipers, and asked whether they partitioned niches at a major migratory stopover in Delaware Bay. During migration, shorebirds form large, usually mixed-species flocks, which forage on marshes, mudflats, beaches or similar two-dimensional habitats where all individuals are distributed on the same horizontal plane. These habitats are often …
Variation In Habitat Thresholds: An Analysis Of Minimum Habitat Requirements Of North American Breeding Birds, Yntze Van Der Hoek
Variation In Habitat Thresholds: An Analysis Of Minimum Habitat Requirements Of North American Breeding Birds, Yntze Van Der Hoek
Dissertations, Theses, and Capstone Projects
Many species show dramatic changes in population extinction or persistence probability at particular habitat amounts. These `extinction thresholds' could be translated to conservation targets, under the condition that we can derive generalities. I investigated the level of variation in landscape-level habitat thresholds for a suite of North American, forest-associated, breeding birds. Records from Breeding Bird Atlases and the availability of remotely-sensed land cover data allowed me to compare habitat thresholds for 25 species across the states of Massachusetts, Michigan, New York, Ohio, Pennsylvania, and Vermont. I show that variation in thresholds is considerable (Chapter II, III), as thresholds range from …
Testing Assumptions Of Coevolution In An Egg-Rejecting Brood Parasite Host: Uncovering Sensory, Cognitive, And Evolutionary Drivers Of Responses To Parasitism In American Robins (Turdus Migratorius), Rebecca Croston
Dissertations, Theses, and Capstone Projects
Hosts of brood parasitic birds face fitness costs associated with rearing unrelated offspring. In response, the recognition and rejection of parasitic eggs is a common host defense. Brown-headed cowbirds (Molothrus ater) challenge coevolutionary theory, because although they exploit over 200 host species, they lay non-mimetic eggs, and most hosts do not combat cowbird parasitism with egg rejection. American robins (Turdus migratorius) are one of a handful of cowbird hosts known to recognize and remove cowbird eggs from the nest. I addressed the mechanistic and evolutionary drivers of egg rejection in this host species, by disentangling the roles of spectral tuning …
How Important Is Land-Based Foraging To Polar Bears (Ursus Maritimus) During The Ice-Free Season In Western Hudson Bay? An Examination Of Dietary Shifts, Compositional Patterns, Behavioral Observations And Energetic Contributions, Linda J. Gormezano
Dissertations, Theses, and Capstone Projects
Trophic mismatches between predators and their prey are increasing as climate change causes decoupling of phenological relationships. Predators linked to the life histories of a particular prey will have a more difficult time persisting through environmental change unless they can alter their behavior to maintain the historical match or possess the ability to pursue alternate prey. Arctic predators typically possess flexible foraging strategies to survive in the labile environment, however, quantifying the limits of those strategies can be difficult when life history information is incomplete. In such cases, piecing together different aspects of a predator's foraging behavior, particularly when environmental …