Monday, March 8, 2010
Coyne brings up another way that species evolve, without natural selection, on pgs. 122-24. This is called genetic drift. Genetic drift happens when a relatively small population of organisms reproduces with each other. Eventually, because of how the small population breeds together, variation is lost and it is possible to get alleles in weird ratios or even completely loose alleles. The allele that gets expressed more often is random and environmental pressures do not affect it. Coyne uses the example of weird blood type frequencies in the Amish and Dunker religious communities. What other traits in populations of plants and animals might arise from genetic drift? Are these traits beneficial or hurtful? If they are harmful, what can we do to help populations get rid of the harmful gene (or can we do anything at all)?