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: -The principle of common descent is the demonstration that all living things on Earth have attributes in common, suggesting we arose from a common ancestor. For example, humans and whales are very different creatures, but both have eyes, brains, hearts, and stomachs that work in almost exactly the same ways.

Detailed explanation-3: -Overwhelming evidence shows us that all species are related–that is, that they are all descended from a common ancestor. More than 150 years ago, Darwin saw evidence of these relationships in striking anatomical similarities between diverse species, both living and extinct.

Detailed explanation-4: -The theory of evolution states that all life has a common ancestry. The direct proof of evolution would be knowledge of lines of descent, that is, actual specimens showing gradual transition from form to form. Fossils provide such evidence. The fossil record shows that birds were evolved from reptiles.

Detailed explanation-5: -Darwin proposed that species can change over time, that new species come from pre-existing species, and that all species share a common ancestor. In this model, each species has its own unique set of heritable (genetic) differences from the common ancestor, which have accumulated gradually over very long time periods.