Unit 2 Performance Task: The Flashy Guppy Data Analysis
Introduction: The Flashy Guppy
A properly dressed male guppy, with its bright blue spots and brilliant splashes of orange, can’t help but stand out. But for a fish that spends its life swimming among predators, it seems that good camouflage would have a big advantage over colors that attract attention. If flashiness is a dangerous risk, why do we still see this trait in the population?
Endler’s Research
In the 1970s, a scientist named John Endler studied guppies in Trinidad. He noticed that guppies in different streams looked very different. Even guppies in the same stream looked different. Males from one pool had bright blue and orange spots along their sides, while those farther downstream carried only small dots of color near their tails. Endler also observed differences in the location of guppy predators and in the color and size of gravel in different stream locations.
Endler photographed hundreds of guppies and carefully collected data about their size, color, and the size and placement of their spots. He began to see a strong relationship between where guppies lived in a particular stream and whether the fish were bright or dull. But what was responsible for these trends in coloration? And if bright colors made guppies more noticeable to predators, why should males be colorful at all? To find out, Endler formed a hypothesis based on his observations and then set out to test it. Based on his tests, he made one of the most important discoveries in evolutionary biology.
