Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 4 of 4
Full-Text Articles in Life Sciences
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 …
Methodological Advancements For Improving Performance And Generating Ensemble Ecological Niche Models, Robert Boria
Methodological Advancements For Improving Performance And Generating Ensemble Ecological Niche Models, Robert Boria
Dissertations and Theses
This study employs spatial filtering of occurrence data with the aim of reducing overfitting to sampling bias in ecological niche models (ENMs). Sampling bias in geographic space leads to localities that may also be biased in environmental space. If so, the model can overfit to those biases. As a preliminary test addressing this issue, we used Maxent, bioclimatic variables, and occurrence localities of a broadly distributed Malagasy tenrec, Microgale cowani (Family Tenrecidae: Subfamily Oryzorictinae). We modeled the abiotically suitable area of this species using three distinct datasets: unfiltered, spatially filtered, and rarefied unfiltered localities. To quantify overfitting and model performance, …
The Effect Of The Study Region On Gis Models Of Species Geographic Distributions And Estimates Of Niche Evolution; Preliminary Tests With Montane Rodents (Genus Nephelomys) In Venezuela, Ali Raza
Dissertations and Theses
Various niche-based techniques exist to model a species' potential geographic distribution in a Geographic Information Systems (GIS) framework. These models compare the environmental conditions of localities of a species' occurrence versus those of the overall study region. In addition to uses in areas such as macroecology and conservation biology, this approach has been applied recently to studies of niche evolution and historical biogeography. Definition of the study region is critical for all of these applications but has not been addressed previously. Here, I examine the effect of changes in the extent of the study region on potential distribution models of …
Using Geographically Structured Evaluations To Assess Performance And Transferability Of Ecological Niche Models For Species With Many Occurrence Records: A Test Using The Caribbean Spiny Pocket Mouse, Heteromys Anomalus, Aleksandarc Radosavljevi
Using Geographically Structured Evaluations To Assess Performance And Transferability Of Ecological Niche Models For Species With Many Occurrence Records: A Test Using The Caribbean Spiny Pocket Mouse, Heteromys Anomalus, Aleksandarc Radosavljevi
Dissertations and Theses
No abstract provided.