Date of Award

8-2013

Degree Name

Doctor of Philosophy

Department

Biological Sciences

First Advisor

Dr. Maarten Vonhof

Second Advisor

Dr. Steve Malcolm

Third Advisor

Dr. Steve Kohler

Fourth Advisor

Dr. Amy Russell

Abstract

Simultaneous study of the demographics and genetics of populations are relatively rare within the literature, despite insights their combined use offers regarding the life history, ecology, and evolution of species. Here I take a comprehensive approach, using capture-recapture data, polymorphic microsatellite markers, and various modeling techniques to examine the demographics and genetics of multiple local populations of Spix’s disk-winged bat (Thyroptera tricolor) in southwestern Costa Rica. T. tricolor is a highly gregarious, neotropical bat species known to form kin-based social groups with high retention of offspring of both sexes. The implications of this highly unusual social structure for survival, inbreeding, and population genetic structure were previously uninvestigated. Capture-recapture modeling based on 5 years of data at three sites indicates survival probability in T. tricolor is strongly age-structured, with three stages: juveniles (0.55 [95% CI = 0.41–0.68]), prime-age adults (0.77 [0.62–0.87]), and senescent adults (0.45 [0.38–0.52]). Survival probabilities vary significantly among populations as well, suggesting strong effects of site-specific environmental factors. Using genetic pedigree reconstruction and roosting home range mapping, I examine the effects of mate choice on inbreeding avoidance and gene flow. Analyses indicate that despite sharing small home ranges (~ 0.2 ha) with close relatives, T. tricolor mate outside of their kin-based social groups with individuals separated by large distances (~ 500 m). Such a pattern of mate choice has the effect of dispersing alleles, despite low juvenile dispersal from natal patches. I further evaluate the potential for a polygynous mating system in this species by comparing genetic and demographic estimates of effective population size Ne. Genetic estimates indicate Ne is significantly lower than adult population size N with Ne/N ratios of 0.28–0.42. Demographic modeling based on capture-recapture data suggests low Ne values are the result of few males (< 10%) achieving reproductive success, consistent with polygyny. Utilizing a comprehensive approach to study the demographics and population genetics of this species provides insights into life history characteristics that would not otherwise be possible, including strong age-structured survival, effects of mate choice on inbreeding avoidance, and the influence of polygyny to reduce genetic diversity within populations.

Access Setting

Dissertation-Open Access

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