| PURPOSE |
This experiment determined an evolutionary timeline for
the origination of trichromatic color. Previously it was believed
that only Old World monkeys, apes, and humans evolved trichromacy because
previously observed prosimians only have monochromatic or dichromatic vision. |
| PROCEDURE |
Li and Tang used electroretinographic flicker photography
to determine the maximum wavelength of light that 20 species of prosimians
could see. By this process, these scientists were able to determine
the critical sites in alleles that code for color vision. In this
way, they could see if there was a polymorphism that allowed for color
vision. |
| RESULTS |
- Nocturnal prosimians are monochromatic, as they have
no functional autosomal opsin gene
- Diurnal prosimians have a functional autosomal opsin
gene and a functional X-linked opsin gene
- There is a middle- and long-wavelength opsin gene polymorphism
in two major diurnal prosimian lemurs. This polymorphism, according
to Li and Tang, should enable a heterozygous female to be trichromatic.
Although these findings by no means solidify this claim,
it provides an excellent hypothesis for the evolution of trichromacy.
An indication that these animals have some color vision provides the necessity
of more studies of color vision in prosimians. |
