AP BIOLOGY

Detailed explanation-1: -Common descent is an effect of speciation, in which multiple species derive from a single ancestral population. The more recent the ancestral population two species have in common, the more closely are they related.

Detailed explanation-2: -In modern usage, a monophyletic taxon is defined as one that includes the most recent common ancestor of a group of organisms, and all of its descendents [as in (a)]. Such groups are sometimes called holophyletic.

Detailed explanation-3: -The pattern of branching in a phylogenetic tree reflects how species or other groups evolved from a series of common ancestors. In trees, two species are more related if they have a more recent common ancestor and less related if they have a less recent common ancestor.

Detailed explanation-4: -That’s because closely related species most likely diverged from one another fairly recently in the evolutionary span. Thus, they haven’t had as much time to accumulate random mutations in their genetic codes.

Detailed explanation-5: -DNA evidence for evolution Biologists often compare the sequences of related (or homologous) genes. If two species have the “same” gene, it is because they inherited it from a common ancestor. In general, the more DNA differences in homologous genes between two species, the more distantly the species are related.