Conclusion: Exhibitionism Explained
We've seen in our simulations that the more brightly colored a male
guppy is, the more likely he will be seen -- and eaten -- by a predator. In a simulation
or in the wild, where predators are plentiful, male guppies become increasingly drab over
generations, pushed by predation pressure toward greater camouflage.
So if camouflage confers such an obvious survival benefit to prey
species like guppies when it comes to predator avoidance, what possible advantage could
there be to sporting colors and patterns that make an individual more conspicuous?
The answer lies in the fact that guppies have to do more than just
survive. They also have to reproduce -- and to do that, they have to attract mates. The
"flashier" a male guppy is, the more likely a female guppy will choose him as a mate,
giving him the opportunity to pass his genes along to the next generation. This is sexual
selection at work, and it is the force that pushes guppy coloration toward conspicuousness
just as hard as predation pushes coloration toward drabness.
There may be several evolutionary reasons why female guppies prefer
flashy males. On the most basic level, the male with the biggest, brightest tail spot
announces most loudly, "Hey, I'm over here" to any female within eyeshot. Flashy colors
are simply easier to locate.
Bright colors may also indicate good genes, in the way the strong
physique of a human athlete is a direct indicator of that individual's health and
vitality. And more indirectly, bright coloration may signal to a potential mate that
he's got something else going for him. After all, he's been able to survive the very
handicap -- conspicuousness to predators -- that his flashiness creates.
Whatever the reasons, it is clear from the research of Endler and
other evolutionary biologists that male guppies live in the crossfire between their
enemies and their would-be mates, with the opposing forces of predation and sexual
selection forever pushing the guppy coloration in opposite directions.