Matthew Choi Kustra

UC Santa Cruz

“The Evolutionary Consequences of Cryptic Female Choice”

I research cryptic female choice—a process in which females bias fertilization to specific males—which is a relatively young field partially due to historic biased interests in male-mediated processes. Specifically, I use empirical work on the ocellated wrasse (Symphodus ocellatus) to understand how females can influence the evolution of male behavior and simulations to understand how cryptic female choice can cause speciation (the creation of new species).


I research the evolutionary consequences of cryptic female choice. In my empirical work, I use a combination of experimental and behavioral research on a Mediterranean fish species, the ocellated wrasse (Symphodus ocellatus). I am investigating (1) how the social environment and behavioral interactions influence the timing of mating, (2) how the presence of ovarian fluid (fluid coating the eggs) influences the timing of fertilization, and (3) how these processes feedback into one another to ultimately shape the evolution of male behavior. So far, we have found that busier nests and mating scenarios allow some males to mate faster. My theoretical work uses simulations to shed light on the coevolutionary dynamics of cryptic female choice. Specifically, how female traits shape the evolution of male traits. So far, we have found that isolated populations can have codivergence in male and female traits, potentially leading to reproductive isolation. I am currently testing how well cryptic female choice can maintain reproductive isolation and contribute to creating new species.

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