Show Me The Science Month Day 7
The birth of new species always involves a barrier to cross-breeding between two different groups of the same species. This barrier may start out as a geographical barrier (two raccoon populations on different sides of a mountain never encounter each other and thus fail to interbreed), but however it starts, reporductive barriers always turn into a genetic barrier. To form new species, two populations of organisms have to drift apart genetically.
The genetic split can happen in a variety of ways, as scientists are discovering in the their quest to find 'speciation genes.' It can happen because
a selfish gene fails to be shut down in the offspring of cross-breeding flies, and it can happen because
one mouse gene doesn't work right when it encounters genetic variants from another subspecies.
A report in
Science describes
one more speciation gene, this time in two sub-species of thale cress plants. In this case, the barrier to reproduction is the result of faulty gene copying.