Date of Award


Document Type

Open Access Dissertation


Biological Sciences

First Advisor

Blaine Griffen


Changes in global climate trends have the potential to influence diverse ecosystems at multiple levels of organization, from the species to the community. Changes in other environmental variables, such as those resulting from pollution and habitat modification, also have the potential to impact species fitness and alter species interactions. This dissertation employs a multi-focal approach to investigate species responses to two main topics: climate change and environmental heterogeneity. To investigate the first topic, this work focuses on the climate change-induced range expansion of the mangrove tree crab Aratus pisonii into novel salt marsh habitats. It investigates latitudinal patterns of life history traits, as well as alterations of these life history characteristics associated with the species’ range expansion. This work compares fitness metrics and selection pressures in historical and novel habitats, and also investigates phylogeographic patterns of genetic variation in A. pisonii to provide insight into the relative roles of phenotypic plasticity and local adaptation in the phenotypic changes facilitating its range expansion. To investigate the second topic, this dissertation provides a mechanistic understanding of how diet, which is easily influenced by changing environmental conditions, impacts the physiology and reproduction of A. pisonii. Finally, this dissertation investigates the impact of past niche construction (i.e. physical habitat modification) on the intensity and spatial variation of current plant-animal interactions. Collectively, this work assesses the diverse impacts of various environmental changes on multiple levels of organization, from the genetic to the individual to the community level.


© 2015, Megan Riley

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