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Owl Eye Color
Name: Jason C.
Status: educator
Age: 20s
Location: N/A
Country: N/A
Date: 3/26/2004
Question:
I would like to know why it is that different species of
owls have different color eyes? I know that the two main colors are
brown as in the barred owl and yellow in the great horned and orange in
European owls. I also know that melanin is what determines the color but
why is the color determined by species? I have been researching this for
a while and have not been able to find a solid answer, just the same
speculations as I came up with. Any information on this topic would be
most appreciated.
Replies:
First off...melanin is not the only determinant of eye color. In humans,
eye color is not simply a dominant recessive association of the two alleles.
If it was, then how would humans have the many shades of brown, the many
shades of blue and green. The thickness of the iris plays a role also,
which is certainly polygenic. I think rather than asking, " why it is that
different species of owls have different color eyes", perhaps a more
appropriate question is, "what advantage is there for the different species
to have those colors?" As a biologist, I ask this question when I am
wondering why a certain trait exists. There must be some evolutionary
advantage. Also, I would reframe the question, "why is color determined by
species" to what advantage in a certain species would a certain eye, or skin
color serve?" A species no more determines the color of its eyes any more
than a human being, because it is a homo sapiens, determines that it has
mammary glands, is bipedal and communicates with spoken language. The traits
we recognize in species help us define and recognize a species but these
traits do not in statically determine the species. The species accumulates
these traits through evolution because the environment has placed a
selective pressure on the evolving species to survive with those traits.
pf
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