Blue-eyed lemurs: not HERC2
The genetics of blue eye color in humans is almost entirely controlled by a single SNP in a conserved non-coding region in an intron of HERC2, as was strikingly demonstrated in a recent study on using genetics to predict eye pigmentation.
Humans are not the only primate to have blue eyes–one notable example is the blue-eyed black lemur (pictured on the right). As it’s well-known that convergent evolution in pigmentation has occurred in many taxa via similar genetic mechanisms (eg. MC1R), one obvious question is: have similar genetic changes led to blue eyes in humans and other primates? For blue-eyed lemurs, a new study demonstrates that, well, the answer is no. The authors sequence the region known to be causal for human blue eyes in both blue-eyed black lemurs and a closely-related, non-blue-eyed species, and find no differences.
Though this is a negative result, it’s still kind of fun, and establishes a nice example of convergent evolution via separate genetic mechanisms in primates.
some cats have blue eyes too (siamese?). i wonder what the genetics under that is.
http://dels.nas.edu/ilar_n/ilarjournal/46_4/pdfs/v4604Kaas.pdf
It’d be interesting to look at Siamese cats, but I bet the genetic mechanism is different since Siamese cats were created by Satan as a conduit to pass messages between the earthly world and the world of darkness.
I’m betting the codon sequence is something like:
ATC TCT GGT GTT 666 CAT 666 CAT 666 AGG ACC CCA CAG
AFAIK, Siamese are the only cat breed that you can train to wear a collar and go for a walk on a leash. They really are outliers.
Blue eyes in Siamese cats is likely due to a tyrosinase mutation: http://www3.interscience.wiley.com/journal/118652329/abstract
[Well, that's proximate, Satan undoubtedly ultimate]
We did sequence this same HERC2 region for a few Burmese cats and Siberian huskies – they have the same conserved mammalian sequence.
@Sandgroper, you said…_Tame_Silver_Fox.jpg (Blue eyes aren’t a “normal” eye color for foxes, AFAIK. But I’m not an expert on foxes.)
AFAIK, Siamese are the only cat breed that you can train to wear a collar and go for a walk on a leash. They really are outliers.Reminds me of the Tame Silver Fox study. Those things were tame too, and some developed blue eyes: http://en.wikipedia.org/wiki/File:Russian
Would anyone know why some animals (some skinks, giraffes, bears, and dogs, and some others Im sure) have blue tongues?
interesting. dogs are getting all the press/investment these days, i wonder when the genomic tools for mapping in cats will get to the same point.
i wonder when the genomic tools for mapping in cats will get to the same point.
when cats decide to cooperate.
HERC2 isn’t the only mechanism for blue eyes in humans though, is it? For example, refer to this paper…
http://www.springerlink.com/content/2045q6234h66p744/fulltext.html
Assuming I’m read it correctly, blue eyes with brown spots doesn’t seem to be caused by HERC2.
(I’m drawing it from the part, in the paper linked to above, that says, “Blue with brown spots (with brown) scored as ?unknown? in the linkage and association studies.“)
HERC2 isn’t the only mechanism for blue eyes in humans though, is it? For example, refer to this paper…
3/4 of the variance. power law distribution; most variance is due to a few genes.
Darn. I could have sworn it was introgression.
Charles, that was an interesting study. Blue eyes with dark spots seems to be caused by a completely different gene than blue eyes without dark spots. As non-spotted “true” blue eyes may still have a faint haze of brown around the pupil when studied very closely, it seems possible that there could be some overlap between the phenotypes in some cases. It it interesting that the spotted phenotype is the eye color associated with blonde hair.
It is also very interesting that this spotted kind of blue eyes can sometimes express as regular brown eyes. (A spotted blue-eyed person and a blue-eyed person can have children who are blue-eyed, spotted blue-eyed, or regular brown. Those regular-appearing brown-eyed children could then have spotted-blue-eyed children. The gene for spotted blue eyes seems to act almost as a kind of wildcard and can express several different ways.)