Question

Scenario: The butterflies Heliconius melpomene and H. erato each show extraordinary geographical variation in coloration, and their colors vary in parallel.

Both species gain a fitness advantage by resembling the other because birds are more likely to associate their coloration with distastefulness and so avoid attacking them.

In field experiments, butterflies were marked and released with two color patterns: the local pattern and a pattern from one of the neighboring races.

Butterflies with the local pattern survive more than twice as well as those with the “wrong” color pattern.

What does this experiment suggest about the type of selection is occurring in these butterflies?

Answer 1

Most of the Insets and small birds and animals have the habit of Mimicry to escape from its predators by appearing like a bigger animal or by adapting the color of the surroundings. In the case of butterflies mimicking is very common.

Heliconius Melpomene so much resembles with its sister species Heliconius Erato, each developing similar bright color patterns. The Heliconius Melpomene correspond to at least 20 Heliconius Erato subspecies. This coloration warns its predators that the butterflies are distasteful and could be avoided. This type of mimicry is known as Müllerian mimicry.

Some of the geographic forms of Heliconius Erato (top row) and H. Melpomene (bottom row)

Infield experiments, Butterflies with the local pattern survive more than twice as well as those with the “wrong” color pattern. As mentioned above the only defiance mechanism of this butterflies was to escape from the birds by mimicry, the butterfly with wrong color pattern can become the attraction to its predators compare to the local bright color patterns.