Masters Theses

Date of Award

12-1985

Degree Type

Thesis

Degree Name

Master of Science

Major

Ecology and Evolutionary Biology

Major Professor

Gary F. McCraken

Committee Members

Arthur C. Echternacht, Edward Clebsch

Abstract

Four species of hermaphroditic terrestrial slugs of the family Philomycidae (Mollusca: Pulmonata) were collected at 13 sites in Tennessee and one site in Virginia. A total of 343 individuals were examined electrophoretically at 11 allozyme loci. These data were used to assess: (1) breeding system in all four species, (2) interdemic and interspecific systematic relationships, and (3) demic structure in Philomycus carolinianus, the most abundant species collected. Breeding system was inferred from analysis of genotypic frequencies within demes. It was concluded that all four species use outcrossing as the primary breeding system in all populations examined. The genetic identities among demes, among species and among genera were similar to values for the same comparisons in other studies and are in good agreement with systematics based on morphological characters. In the one species examined in greatest detail. Philomycus carolinianus, there was significant heterogeneity among demes. This differentiation among demes was attributed to genetic drift due to restricted gene flow. Genetic identities were not significantly correlated with geographic distance between demes. Analysis using hierarchical F-statistics demonstrated that more than half of the differentiation among demes was accounted for by differentiation at the smallest geographic scale. The Tennessee River system also appeared to form a major barrier to gene flow. It was concluded that the populations of Philomycus carolinianus are highly fragmented and gene flow among these demes is restricted by distance and the barrier of the Tennessee River.

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