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Full-Text Articles in Life Sciences
Dynamics Of Avian Elevational Ranges Reveal Hidden Evolutionary Forces, Chauncey Gadek
Dynamics Of Avian Elevational Ranges Reveal Hidden Evolutionary Forces, Chauncey Gadek
Biology ETDs
The distribution of life across the Andes mountains reflects historical elevational-range contraction and expansion. Whereas contraction implies specialization, expansion requires overcoming hidden barriers. Three eco-evolutionary phenomena may drive patterns in rates of elevational range evolution: (1) The Dobzhansky-MacArthur Phenomenon (DMP) predicts lower rates of upward expansion with harsher physical conditions, while downward expansion increases with lower diversity; (2) the evolutionary tendency toward specialization predicts contraction increases when ranges are broad; and (3) natural selection for respiratory performance could suppress expansion across mid-elevations due to gene-environment mismatch. We modeled elevational range shifts of Neotropical landbirds. Contrary to the DMP, upward expansion …
Diet Specialization Does Not Explain Occupancy Or Abundance In A Test Of The Resource Breadth Hypothesis In A Small Mammal Community, Deborah R. Boro
Diet Specialization Does Not Explain Occupancy Or Abundance In A Test Of The Resource Breadth Hypothesis In A Small Mammal Community, Deborah R. Boro
Biology ETDs
The abundance-occupancy relationship (AOR) is a recurrent pattern in ecology and biogeography, in which species with expansive distributions are locally common while those with restricted distributions are locally rare. Despite occurring across a wide variety of taxa and spatial scales, the mechanisms underlying AORs are not well understood. I tested two such mechanisms regarding dietary generalism in a guild of 8 small, herbivorous African mammals: (1) the degree to which diet was explained by food availability, and (2) population-level diet breadth. I expected that food availability would better predict diet for abundant, widespread species than rare, restricted species. Additionally, I …
Where The Wild Things Are: Investigating Body Size As A Mechanism For Persistence, Meghan A. Balk
Where The Wild Things Are: Investigating Body Size As A Mechanism For Persistence, Meghan A. Balk
Biology ETDs
Body size is a trait under selection. Genetic drift, climate, diet quality, and biotic interactions all select upon body size at the population, species, and community levels. These factors can be important in the context of rapidly changing climate. One of the ways an animal can persist in its environment is through morphological adaptation in situ. Here, I investigate four questions relating to the evolution of body size: (1) what is the limit in body size change in response to climatic change; (2) how does body size influence the thermal tolerances of animals; (3) how does body size evolve …
Constraints On Distributions And Diversity Of Birds And Mammals Over Variable Environments, Trevor S. Fristoe
Constraints On Distributions And Diversity Of Birds And Mammals Over Variable Environments, Trevor S. Fristoe
Biology ETDs
The distributions of species are determined by intrinsic factors such as physiological tolerances as well as extrinsic factors of the environment such as the availability of resources. While physiological tolerances generally change over evolutionary time scales, changes in environmental productivity due to processes such as succession or seasonal progression often occur over ecological times. I address both physiology and resource availability as drivers of the distributions and diversity of endothermic birds and mammals using a macroecological approach and a metabolic perspective. Migratory birds, altering communities over seasonal cycles, provide a unique opportunity to investigate the drivers of distributions and diversity …