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Full-Text Articles in Ecology and Evolutionary Biology
The Effects Of Anthropogenic Stress On Nitrogen-Cycling Microbial Communities In Temperate And Tropical Soils, George S. Hamaoui Jr.
The Effects Of Anthropogenic Stress On Nitrogen-Cycling Microbial Communities In Temperate And Tropical Soils, George S. Hamaoui Jr.
Doctoral Dissertations
In this dissertation several research studies are discussed that characterize the effects of anthropogenic, or human-induced, stress on both ammonia-oxidizing and total bacterial soil microbial communities. The disturbances of land-use change in tropical, South American rainforests and artificial warming and nitrogen (N) fertilization in temperate, North American forests were investigated as these disturbances represent past and current disturbances caused by human landscape alteration and climate change. Initially, the response of soil ammonia-oxidizing microbial communities to land-use change from primary rainforest to pasture and, finally, back to secondary forest was determined. Next, these analyses of land-use change effects were expanded to …
The Role Of Phenotypic Integration In Mammalian Tooth Function And Jaw Morphological Diversity, Andrew Conith
The Role Of Phenotypic Integration In Mammalian Tooth Function And Jaw Morphological Diversity, Andrew Conith
Doctoral Dissertations
Here I investigate how two major components of the mammalian feeding system, teeth and jaws, are influenced by functional, environment, and developmental factors. First, I build physical models of the molars from two early mammals, Morganucodon and Kuehneotherium, and compare their ability to process a proxy food item. Early mammals were under strong selection to reduce metabolic costs, so any savings in energy during feeding would be advantageous. I tested the ability of both mammals to process a hard and soft food item with material properties similar to that of the insects they would have likely consumed. Morganucodon was …
Burrowing And Walking Mechanisms Of North American Moles, Yi-Fen Lin
Burrowing And Walking Mechanisms Of North American Moles, Yi-Fen Lin
Doctoral Dissertations
Moles (Family Talpidae) are a classic example of extreme specialization, in their case highly derived forelimb morphologies associated with burrowing. Despite many observations of mole burrows and behaviors gathered in the field, we know very little about how and how well moles use their forelimbs to dig tunnels and to walk within the built tunnels to collect and transport food. The first chapter investigates the effect of soil compactness on two sympatric mole species under controlled laboratory conditions. My results demonstrate that increasing soil compactness impedes tunneling performance as evidenced by reduced burrowing speed, increased soil transport, shorter tunnels, shorter …