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Australia, bird with three-toed feet

A. At one time the continent of Australia was connected to Asia. About 50 million years ago Australia became separated. It has many unusal animal not found elsewhere, such as the kangaroo and the koala bear. Using the concepts of geographic isolation the gene pool, explain why these animal developed.

B.A species of bird with three-toed feet feeds mostly on worms and crwling insects. Over a period of several thousand years, the ocean level rises, and the region where the bird lives is flooded. Over several thousadn years ago or so, the birds' descendants evolve webbed feet and begin to feed on fish. Is this an example of gradualism or punctuated equilibrium? Can you give me an explanation of this answer?

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A. Australia probably (but this is not absolutely certain) became isolated with a large number of marsupials on it. (Such exist also elsewhere, for example the American Opossum). So the whole - or almost whole - animal population of Australia ...