How is the idea of common descent supported by examples of homologous structures as shown in 16-5?

Question

anonymous · Answer

attachment

pooja195 · Answer

what do you think?

pooja195 · Answer

ok let me rephrase that do you have an answer to your question sort of?

abhisar · Answer

Homologous structures are those which show anatomical similarity like pattern of bones but they perform different functions. For ex: vertebrate forelimbs. These structures indicate that they have descended from a common ancestor via divergent evolution in order to survive in changed environmental conditions.

Now let's try to understand it with an example,

$\Delta$ The forelimbs of vertebrates, such as man, cheetah, whale and bat are good examples of homologous organs. The forelimbs of these animals have different shapes and serve different purposes. They are used for grasping in man, for running in cheetah, for swimming in whale and for flying in bat. They are , however, built on the same plan. In each case, the forelimb consists of upper arm having carpals in the wrist, metacarpals in the palm, and phalanges in the digits. All vertebrates have basic similarity in the structure of their forelimbs because they inherited it from an ancestor which had five-digited limbs or pentadactyly limbs. The pentadactyl limbs of the ancestral vertebrate became modified according to the special needs of the subsequent generations during the course of evolution. The modification has been minor, e.g reduction in the number of digits, fusion of certain bones and external form.