Publication Date

Fall 12-4-2021

Document Type

Thesis

Degree Name

Master of Science in Biology (MS)

Department

Biology

Committee Chair

Cord Eversole

Committee Member

Neal McReynolds

Committee Member

Marvin Bennett

Committee Member

Dan Mott

Abstract

Small mammals play many roles in ecosystems and are known as great indicators of overall ecosystem function and health, but they are also highly competent hosts for ticks and tick-borne disease. In this study, I gathered data on small mammal community ecology and species diversity, abundance, and overall ectoparasite (i.e., ticks) dynamics in a south Texas Tamaulipan thornscrub habitat. I also assessed differences in these parameters in edge versus interior habitats across a gradient of habitat fragmentation and species assemblage. Lastly, I assessed which host and environmental factors can be utilized for predicting parasitization of small mammals in this habitat. Results of this study included a total of nine small mammal species collected with Sigmodon hispidus (n=581) and Peromyscus leucopus (n=443) being the most abundant. Sigmodon hispidus contained the highest species richness of ticks and P. leucopus contributed 79% of all ticks collected. A total of seven tick species were collected, with Dermacentor variabilis (n=982; 66%) being most abundant. There was no statistical difference found between edge and interior habitats for diversity of small mammals (F=1.56; P=0.24), diversity of ticks (F=0.14; P=0.72), or tick loads of any species including Chaetodipus hispidus (F=1.82; P=0.18), Neotoma micropus (F=1.67; P=0.237), Onychomys leucogaster (F=0.99; P=0.322), Peromyscus leucopus (F=1.65; P=0.199), Perognathus merriami (F=1.22; P=0.271),

Reithrodontomys fulvescens (F=1; P=0.334) and Sigmodon hispidus (F=0.72; P=0.397). However, distance from trail and diversity of vegetation were important factors in predicting tick parasitization of small mammals. Other factors which resulted in increased tick loads on small mammals were sex (F=9.09; P=0.003) and the interaction between sex and reproductive status (F=4.5; P=0.03) for Sigmodon hispidus, as well as sex (F=4.09; P=0.04) and reproductive status (F= 5.74; P=0.02) for Peromyscus leucopus. The AICc modeling results for all small mammals indicated that the model that included season, year, vegetative diversity, litter depth, canopy cover, small mammal species, sex, and reproductive status was the most informative model in predicting parasitization of small mammals (AICc= 950.45; wi = 0.14). These parameters along with others presented in each of the models can be utilized in lowering disease risk in arid habitats such as South Texas.

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