Does Sympatry Influence Dietary Niche Overlap? an Analysis of Gut Content in Poeciliopsis prolifica and Poeciliopsis latidens (Cyprinodontiformes: Poeciliidae)

Authors: Alexandra Duffy, Andrea Roth-Mozón, Jerald B. Johnson

Year: 2018

Abstract

Interspecific competition for resources can promote adaptive radiations through the processes of competitive exclusion and character displacement. The expectation is that if similar species co-occur (sympatry), they will evolve distinct dietary niches to avoid negative effects due to competition. In this study, we investigated trophic resource use in two congeneric livebearers fishes, Poeciliopsis prolifica and P. latidens that co- occur in western Mexico. We compared the digestive tract weight, length, and gut content between sympatric and allopatric populations of both species. We expected to find less dietary overlap in both species when they were found in sympatry than when found alone in allopatry. We will discuss the most prominent food items in each species and potential contribution of dietary niche differentiation to the stable coexistence of these two closely-related species. This work will aid our understanding of how species can coexist and what promotes species divergence in resource use when species occur in sympatry. Additionally, this study will provide important ecological information of these species, as it is the first dietary description for both species.