Date: May 3, 2016
Source: Wiley
In some animals, the same species
can occur in two or more color types, or morphs. New research may help solve
the mystery of how this can occur despite the pressures of evolution.
Researchers who studied Black
Sparrowhawks, which occur as either dark or light birds, found that the hunting
success (measured by how much food they brought to their chicks) of each color
type differed depending on light levels. Thus dark birds did better when it was
darker and light birds did better when it was brighter. When the investigators
looked at Black Sparrowhawks across the whole of South Africa, they found that
the frequency of the color types varied according to the ambient light levels found
during the breeding season.
"Our study is the first
study to reveal support for the idea that color polymorphism is due to
different morphs being better adapted to different light conditions," said
Gareth Tate, PhD student at the Percy FitzPatrick Institute and lead author of
theEcology Letters study. "This is an important finding and helps
evolutionary biologists understand how multiple color varieties can co-exist
together in the face of natural selection."
Dr. Arjun Amar, supervising
author of the paper added, "We think that dark morph birds capture more
prey in duller conditions because they are better camouflaged against darker
cloudier skies. Within our study area, high rainfall coincides with when the
species is breeding, and this may also explain why we have so many of this
usually rare colour type here."
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