Document Type

Thesis

Abstract

According to previous work along the western Atlantic Coastal Plain, 70% of molluscan species went extinct during a two pulsed event across the Plio-Pleistocene boundary; yet the nature of this extinction event is different north and south of the biogeographic boundary represented by Cape Hatteras, North Carolina. Although the evolutionary effects of this extinction have been studied, the community-level ecological effects are poorly understood. This research focuses on the confamilial predation of naticid snails and seeks to determine changes in the degree of cannibalism across the biogeographic boundary during the late Pliocene. Float and museum collections of the Yorktown (Moore House Member) and Duplin Formations (sampling before the extinction) and the lower Waccamaw and Chowan River Formations (sampling after the first pulse of extinction) were used in this study. Frequency of cannibalism per collection, and naticid size were analyzed. Data were collected from 21 localities across the Coastal Plain of Virginia, North Carolina, and South Carolina representing 3 units north of Cape Hatteras, and three units south. 1,951 specimens were analyzed. Results indicate that naticid cannibalism increases across the Plio-Pleistocene extinction and is greater north of the biogeographic boundary. Results also indicate a statistically significant decrease in naticid size across the biogeographic boundary. A statistically significant increase in maximum size occurred south of Cape Hatteras. Additional analysis of community level data from Huntoon (1999) suggests that the observed increase in cannibalism was due to a decrease in preferred prey abundance. These results suggest that naticid competition increased after the extinction event because of reduced preferred prey abundance which lead to an increase in cannibalism.

Date Awarded

2009

Department

Geology

Advisor 1

Rowan Lockwood

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