An excess of nonsynonymous fixed mutations between species is likely due to:
A)natural selection.
B)random genetic drift.
C)a catastrophic event.
D)inbreeding.
E)immigration.

Question

Quizplus · Accepted Answer

An excess of nonsynonymous fixed mutations between species suggests that natural selection is at play. This is because nonsynonymous mutations affect the amino acid sequence of a protein, and if these mutations are fixed in a species it suggests that they provide some selective advantage for that species compared to its ancestor. Random genetic drift would not necessarily result in an excess of nonsynonymous mutations, and neither would catastrophic events, inbreeding, or immigration.

An Excess of Nonsynonymous Fixed Mutations Between Species Is Likely