Question

“Every species has come into existence coincident both in time and space with a pre-existing closely allied species.”

Alfred Russel Wallace, 1855

Wallace, A. R. 1855. On the law which has regulated the introduction of new species. Annals and Magazine of Natural History, 2nd Series, 16:184–196.

Wallace presents several examples of ‘evidence’ that supports his statement. Discuss two of these.

Answer 1

According to Alfred Wallace, the new species have originated from the already existing species either due to geographical isolation or reproductive isolation. This statement is accepted by many scientist because Wallace has given many evidences in support of his statements. The two evidences are"

1. The flora and fauna present in the Galapagos island have high similarity with the mainland plants and animals from which Galapagos island have originated from geographical isolation. The Darwin also seen that Galapaoes finches have many similarity with the finches of mainland. This evidence suggest that plants and animals species have living on Galapagos island were originated from mainland plants and animals.

2. When a mountain range, attain a high elevation and remain that for a long time, the species of the two side of elevation will becomr  different from each other but once they were same.