Although this may seem off-topic at first, I feel this recent study in wild desert mouse populations serves as a genetic proof of the kind of melanic selection the peppered-moth studies suggest. I'm interested to see if others agree...
The genetic basis of adaptive melanism in pocket mice.Nachman MW, Hoekstra HE, D'Agostino SL. Proc Natl Acad Sci U S A. 2003 Apr 29;100(9):5268-73. PMID: 12704245
Briefly: Populations of "rock pocket" mice live in (mostly light-colored) rock outcroppings in the desert, and since mice avoid open areas, they are effectively geographically isolated to the rock outcroppings. Geologically recent outcroppings have formed through volcanic activity, these outcroppings are dark colored. Mice living on the light-colored rocks have light coats, those on the dark rocks have dark coats - the selection here being predation by birds.
The authors were able to determine the specific gene mutation (a melanocortin receptor) responsible for the melanism in one population of dark mice. Importantly, they were able to show that the dark coat allele was relatively young compared to the (presumably ancestral) light coat allele, since the light coat allele had ten times as many variant neutral polymorphisms. Also, the dark allele is dominant, so its initial recipient would have immediately received the benefits of camoflauge.
I guess part of the lure of the peppered moth is the idea that their selection has been witnessed (depending on who you ask) on a recent human timescale - though I appreciate that the dark mice with the younger allele in the above study are found on the geologically younger outcroppings - new niches were filled by those that adapted.
Unfortunately, the study includes photos of mice of different coat colors on different colored rocks - I'm sure the experiments will be discredited someday because the pictures were likely staged...
To some extent I don't understand the obsession surrounding the peppered moth observation (or its discreditation), given the many other examples of selection.
Thanks.