Niche breadth in clonal and sexual fish (Poeciliopsis): a test of the frozen niche variation model

The evolution and subsequent maintenance of sex has been debated for many y ears, and there are numerous aspects that remain poorly understood. When co mparing sexual with asexual reproduction, there are many more apparent bene fits to being asexual than sexual. The frozen niche variation (FNV) model d escribes how asexual clones can arise from a sexual population and how the two reproductive types can coexist. Herein we compared three sympatric popu lations of sexual and asexual fish (one sexual population, Poeciliopsis mon acha, and two clonal populations, P. 2-monacha-lucida) to test the assumpti on of the FNV model that sexual populations have a broader dietary niche (a s measured by gut contents analysis) than clonal populations. Individual se xual fish had similar dietary breadth when compared with clonal individuals . However, dietary breadth for sexual populations as a whole was broader th an for either clonal population, indicating differences in between-individu al dietary choice. Our results support the primary assumption of the FNV mo del and thereby provide a possible explanation for the maintenance of sexua l reproduction in this clonal-sexual complex.