The most recent study in BMC Evolutionary Biology found that while females prefer reds and yellows they go for the winner of fin-to-fin combat in a significant number of cases. In the study, the larger parae almost always prevailed, thus gaining a mating advantage despite its less-than-desirable coloration. Immaculatas, which are the smallest males, generally shunned the showy displays of violence and were mostly ignored by all but yellow males. The larger yellows almost always defeated immaculatas, stopping them from approaching females.
"In the absence of male-to-male competition, we found that females will almost always choose a red male," Hurtado-Gonzales says. "However, if the red loses a fight, the female will generally seek out the winner. In most cases, that is the larger parae, which is the most dominant male."
Immaculatas compensate for their lack of physical prowess and attractiveness through a mating strategy that relies on stealth. In a 2009 study published in the journal Animal Behavior, Hurtado-Gonzales found that the immaculatas' drab color provides camouflage that enables them to stealthy mate with females while the more colorful red males were wooing them. Females are promiscuous and will mate with multiple males. Additionally, immaculatas have developed larger testes, which produce more sperm, providing a post-mating advantage in the race to fertilize female eggs.
Finally, in a study published earlier this year in the Journal of Evolutionary Biology, produced by the European Society for Evolutionary Biology, Hurtado-Gonzales found that a common predator of Poecilia parae prefers to dine on reds and yellows, most likely because their striking colors make them easier to see. This predatory disadvantage contributes to the lower numbers of reds and yellows in the overall population.
"It seems that within an evolutionary scale, the less attractive males persist in the population ove
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