Previous research has shown partial prezygotic isolation between two lineages of Poecilia reticulata: the common guppy and the endlers livebearer. Female mate choice is thought to drive this isolation. This isolation has resulted in morphological and behavioral divergence, and may signal incipient speciation. The endler morphotype is marked by distinct coloration patterns and an elongated body (1). Our experiments investigated the roles of visual and behavioral signals in determining female preference for their ancestral lineage. Female preference for males of her ancestral lineage could allow females to select for genes well suited for the environment, or be a result of run-away sexual selection since females do inherit trait preferences (2) and no genetic incompatibility between the populations has been observed.

http://www.reed.edu/biology/professors/s...FinalMonday.pdf