Guppies Experiment

In his original findings, John Endler (1978) reported that male guppies in high predator areas tend to have patterns that resemble their environment so they don’t stand out. Guppies with low or no predation, tend to not blend in and are brighter with more and larger spots (Endler, 1978). Endler thought that this could be happening because color patterns are molded by natural selection and sexual selection. Although brighter males are often preferred by the females, they are also more likely to be eaten. In areas with high predation, natural selection favors males with less coloration.
He tested his hypothesis with an experiment performed in 10 ponds built in a greenhouse. Four pools would eventually house guppy populations with high-predation, 4 would house guppy populations with medium-predation, and two would be the controls that housed guppies with no predators. The expectation was to see the following events take place; that color patterns would increase or decrease depending on the level of predation, that the changing color patterns …show more content…
To show that these finding are accurate against all guppies of this species, the greenhouse experiment can be compared to a previously conducted field experiment. Endler (1978) and his researchers found a stream that had multiple ponds separated by tributaries and waterfalls to prevent populations from mingling. They took the guppies that were already living in ponds with high predation and moved them to predator-free ponds. The results were measured by how the guppies’ appearance changed after two years in their new pool. The conclusion of the field test supports the findings in the greenhouse experiment. Guppies that are moved away from predators, develop a higher number of spots, an increased size in spots, and an increased diversity in spot coloration (Endler,