MORPHOLOGICAL EVOLUTION!!!

Industrial melanism in British peppered moths has a singular and recent mutational origin. 

van't Hof AE, Edmonds N, Dalíková M, Marec F, Saccheri IJ.

The rapid spread of a novel black form (known as carbonaria) of the peppered moth Biston betularia in 19th-century Britain is a textbook example of how an altered environment may produce morphological adaptation through genetic change. However, the underlying genetic basis of the difference between the wild-type (light-colored) and carbonaria forms has remained unknown. We have genetically mapped the carbonaria morph to a 200-kilobase region orthologous to a segment of silkworm chromosome 17 and show that there is only one core sequence variant associated with the carbonaria morph, carrying a signature of recent strong selection. The carbonaria region coincides with major wing-patterning loci in other lepidopteran systems, suggesting the existence of basal color-patterning regulators in this region.

Science. 2011 May 20;332(6032):958-60. Epub 2011 Apr 14.

Why is this cool?

 If you ever need an example of evolution, the peppered moth is the best ever. Seriously. The story goes that way back before industrialization the peppered moth inhabited some woods in Britain (I leave it up to you to find the exact details).

 

The peppered moth was black and white (hence the name "peppered") in the same way as the trees of that forest and the moths spent much of their time on the trunks of those trees hiding from predators. Well, Britain wasn't keen on being antiquated, so it became industrialized. No biggie. Turns out that industrialization caused a lot of pollution particularly in the forests frequented by the peppered moth. The end result of the pollution was that the once peppered trees were now much darker and a peppered moth that tried to hide on said trees was instantly spotted and eaten by birds. Luckily, the moths had their friend Natural Selection to back them up. 

Natty Sel worked so that the lightest moths were killed and only the darker ones could descend their modification of darker color. Eventually, the once peppered moth was now an indestructible weapon in one color: black. It is a shame that Natty Sel didn't pick a cooler color like gun metal gray.

 It is a fun story, but no one ever found the exact genetic change that led to the blackness, until today's paper. The researchers "genetically mapped" the black moth to the genome of the silkworm...I don't know exactly what it means to genetically map something. My first thought is that the genome sequence of the black moth is available, but it is not. I need to read the paper to understand that bit. Anyway, from the genetic mapping, they found that there was a 200 kilobase region with recent strong selection in an area predicted to be involved in wing-patterning.

 You may be thinking:

"Hey, why don't they mutate that area associated with wing patterning and show that it IS involved in coloring?"

 Well, it is not easy to just mutate everything all willy nilly. No one intensively studies peppered moths and they are not a model organism, so no one has worked out the genetic procedures for easy mutation.