2012- 21st Annual NC State Undergraduate Research Symposium

Session Time : 4/10/12 12:15 PM - 4/10/12 1:30 PM

Content Area : Biological Sciences

Poster Appointment: , -

Student Presenters :
Taylor Rose Lansing Biology

Mentors and/or Co-Authors :
Randall Langerhans Biology

Abstract Title : Ecosystem fragmentation leads to utilization of a suboptimal prey type in endemic livebearing fishes of the Bahamas

Abstract :
A common and serious outcome of human-induced habitat degradation and fragmentation is loss of top predators. Such predator release can permit resilient prey organisms to increase in density as they experience dramatically altered ecological conditions. A fundamental prediction of optimal foraging theory is increased utilization of suboptimal prey types with greater competition for food resources, as might often occur for resilient prey taxa in these human-altered environments. In the Bahamas, anthropogenic fragmentation of wetlands via road construction is widespread, and disrupts hydrological connectivity between fragmented and adjacent marine areas, resulting in the loss of marine piscivorous predators. Here we examine the effects of ecosystem fragmentation on utilization of a suboptimal prey item, molluscs, across multiple islands for each of three divergent lineages of endemic, livebearing fishes of the genus Gambusia. We estimated conspecific density as a surrogate for the intensity of intraspecific resource competition, and employed two methods to estimate prevalence of mollusc feeding: (1) a novel, non-invasive method using x-ray radiographs, and (2) direct stomach-content analysis. Both the density of Gambusia, and the frequency and incidence of molluscivory, increased subsequent to habitat fragmentation. This shift may have a number of important ecological and evolutionary consequences, and highlights a potentially pervasive effect of habitat modification on the foraging niches of native organisms.