You discover that there are actually 2 different species of Drosophila living in a barn, but one is much more common (possibly it is much more successful at competing for resources). You sequence to genes in both species and use the McDonald Kreitman test to assess the role of natural selection in driving the patterns of DNA divergence. The first locus is glucose phosphate isomerase (Gpi), at which you detect 16 fixed differences (3 replacement and 8 silent changes) and 30 polymorphisms (9 replacement and 21 silent). The second locus is alchohol dehydrogenase (Adh) at which you detect 12 fixed differences (9 replacement and 3 silent) and 24 polymorphisms (8 replacement and 16 silent). Is genetic drift or natural selection driving the evolution of each gene?
Its a genetic drift, as Genetic drift causes gene variants to disappear completely. Thus the genetic variation reduces.Here also due to silencing of gene many variants and products are not synthesized.Due to Polymorphism.and silencing many genes are not produced or another function is performed by them,which causes genetic variation.
You discover that there are actually 2 different species of Drosophila living in a barn, but...