The five male subtypes of P. parae and the female (f). Sometimes being flashy isn't the only male strategy that works. Felix Breden/Anna Lindholm

When it comes to choosing a partner, most species have to rely on some version of what we think of as love at first sight. Faced with an onslaught of preening suitors, a female often decides to mate with a fellow based on how he looks. And her choice doesn’t always go with the flow of natural selection: Copulating with a wooer who has impressive feathers or stately antlers may endow her offspring with a quality that makes him better equipped to survive, or it may not. Sometimes a trait that is otherwise useless or even detrimental (think of the cumbersome peacock train) winds up dominating the male population simply because females find it attractive.

But males of the species P. parae -- a guppy-like fish that lives in ditches and streams along the coast of Guyana south to the mouth of the Amazon River -- have managed to prevent female opinion from determining their fate. The fish come in five distinct types, and they’re so different that scientists initially named each as a separate species: The yellow, red, and blue ones are medium-sized; the striped ones (or parae) are bigger and, along with the yellow, more aggressive; and the plain ones (or immaculata) are small and resemble juvenile females.

What’s more, they’re all similarly abundant. While scientists have found that at first glance, P. parae ladies seem to prefer red and yellow males, the blue, striped, and plain ones persist -- often in even greater numbers. How, biologists began to wonder, did the three least-attractive male types evade winnowing by the female cold-shoulder (otherwise known as intersexual selection)?

It turns out that each color has its own set of advantages and disadvantages for both mating and survival, says Syracuse University biologist Jorge Hurtado-Gonzales. For instance, predators also prefer the flashier red and yellow males -- to eat. Meanwhile, the puny, plain males have developed a "sneaker" strategy -- unable to best their counterparts with brawn or beauty, they trick P. parae ladies into thinking they’re one of the girls and then cop a quick mating session before their partner has a chance to say no.

In a study published in December’s BMC Evolutionary Biology, Hurtado-Gonzales also finds that females can be influenced by observing male fights -- their preference often shifts to striped males, the most physically powerful of the types, when they watch them beat up on the more handsome red or yellow fish. And the blues? Hurtado-Gonzales is working on a theory that has to do with how they use their hue in combination with light and color to achieve another sort of advantage.

Understanding how P. parae’s various mating strategies work with other forms of natural selection to maintain a genetically diverse population, says Hurtado-Gonzales, could help scientists develop new resources for protecting other gene pools and species, whether their guys are cute or not.