Doctoral Dissertations

Date of Award

12-1998

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Ecology and Evolutionary Biology

Major Professor

Donald L. DeAngelis

Committee Members

Mike McKinney, Jim Drake

Abstract

The effect of abiotic factors on population dynamics has been a central focus of ecology since its inception. This study examines the role of such factors in variously regulating the dynamics of selected avian and herpetological populations. This is achieved using a landscape ecology approach with special reference to the question of scale. In the first of these investigations, an appropriately scaled spatially explicit individual-based population model is constructed for the Cape Sable Seaside Sparrow (Ammodramus maritimus mirabilis). The model combines information about the sparrow's behavioral and life history characteristics with historical hydrological data, demographic survey data, and satellite-derived vegetation maps. This model is used to investigate the effect of hydrologic patterns on breeding potential. The model was validated by comparison with demographic survey data collected over the period 1981-1997. Population viability analyses are used to con^are the effects of changing various ecological parameters in a series of sensitivity analyses. The results of these analyses support the use of the parameter values (derived from field studies) set in the validation runs. This model has since been used in a species management role within the Everglades National Park to predict the effects of proposed hydrologic scenarios on sparrow demographics.

In the second investigation global datasets, representing various abiotic variables, are used to predict modern distributions of species richness in a number of Australian and North American herpetological taxa. Multiple regression models quantify the relative importance of spatial patterns in temperature, precipitation, leaf area index, and topographic diversity in predicting patterns of species richness. These relationships differ within and between both taxa and continents. Taxonomic divisions at the family level produce more significant models than those produced using divisions at the level of order. The significance of leaf area index and topographic diversity in these models is discussed with reference to evolutionary and conservation issues.

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