Morris Laboratory Research

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Current Projects

Variation in Female Mate Preferences

Not all females prefer the same male or have the same strength of preference, nor do their preferences remain inflexible to environmental influences. While historically considered “noise,” variation in female preference is now being studied for its role in maintaining variation in male traits as well as the evolution of complex male traits. Understanding variability in female preference, and viewing preference as a life history trait, could also improve our understanding of the evolution of female preference itself. Our lab continues to examine the causes and adaptive nature of variation in female preference.

Alternative Mating Tactics

We are currently examining mechanisms that maintain the genetically influenced alternative mating strategies in Xiphophorus multilineatus. In addition to determining if frequency-dependent selection is important, we have shown that variation in female mating preferences could help maintain both courter and sneaker males (Rios-Cardenas, Tudor and Morris 2007). We have found that a population of X. multilineatus fluctuates in the frequency of sneakers and courters, and when the ratio of sneakers to courters was at its highest, the two types were not at ESSt. We are now repeating this experiment for the same population for a sample when the frequency of the two types of males were closer to equal. We are also documenting alternative mating strategies in other species of swordtails with the goal of examining the evolution of these mating behaviors in a phylogenetic context.

Genetic Assimilation and the Evolution of Species

The lab has a growing interest in the evolutionary importance of environmentally influenced traits. We are currently examining the possibility that phenotypic plasticity in the form of alternative phenotypes, followed by developmental character release and genetic assimilation, drove the evolution of X. pygmaeusfrom X. multilineatus. The alternative phenotypes in X. multilineatus consist of males that coax female to mate (larger males that use only courtship behavior and have sexually selected traits) and males that both coax and coerce females to mate depending on the presence of a larger competitor (small males that use both courtship and sneak-chase behavior and have reduced sexually selected traits).