Electronic Theses and Dissertations

Date of Award

1-1-2020

Document Type

Thesis

Degree Name

M.S. in Biological Science

First Advisor

William J. Resetarits

Second Advisor

Christopher J Leary

Third Advisor

Jason D Hoeksema

School

University of Mississippi

Relational Format

dissertation/thesis

Abstract

The Ideal Free Distribution (IFD) is an influential ecological model for predicting distribution of populations. Since its inception, attempts have been made to improve the IFD, including addition of spatial context. Spatial contagion is a newer ecological concept wherein quality of a habitat patch may affect the perception of neighboring patches. Using Cope’s gray treefrog (Hyla chrysoscelis) and Culex mosquitoes (Culex restuans), I conducted a series of outdoor mesocosm experiments to test key predictions of the IFD and address how it interacts with spatial contagion effects. I found some support for the IFD prediction that individual H. chrysoscelis should avoid habitat patches with higher densities of conspecifics although there was not a clear linear relationship, as would be expected. There was a strong effect of distance from the nearest tree line on oviposition habitat selection and an interaction between distance and conspecific density. It is possible that the costs of movement by ovipositing H. chrysoscelis females may outweigh the potential costs of intraspecific competition, which would violate the IFD assumption that individuals are free. Conversely, a second experiment using H. chrysoscelis revealed that the presence of conspecifics can affect the hierarchy of habitat patches by causing females to avoid larger pools that have been previously described as optimal. My results suggest that individuals are capable of distinguishing patches based upon conspecific densities, but the relationship may be a binary threshold rather than a linear relationship. Using C. restuans, I found that while females avoided patches containing conspecifics, resource availability was a more significant predictor of where egg rafts were laid. Resource availability did not have a reward contagion. While competition does play a role in habitat selection, these results suggest that other environmental factors may be more crucial in habitat selection.

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