How does the concept of convergent evolution explain similar

How does the concept of convergent evolution explain similarities in the appearance and function of unrelated taxa in similar biomes from different parts of the world?

- This is related to Whittakers\'s system of classifying biomes.

Solution

Convergent evolution refers to the attainment of similar structures by distantly related animals,. This happens when different groups of animals live a similar way of life. Similar way of life is the rule when they live in the same environment or habitat. The structures developed in convergent evolution are analogous and not homologous.

Aquatic life:

The aquatic vertebrates fishes, Ichthyosaurs and whales are three distant, unrelated groups. They settled in water. Hence all of them developed similar types of adaptive characters. The characters include streamlined body, fins, etc. Convergent evolution leads to the production of analogous similarities among different groups of organisms. This indicates that evolution may lead to superficial resemblence.

Marsupials and Placentals

Marsupial mammals and placental mammals form a suitable example for convergent evolution. Both groups diverged from a common ancestor about 120 milion years ago. After isolation each group evolved independently. Eventhough they are geographically seperated, marsupials in Australia and placentals in North America have remarkable similarities in body shape, diet and locomotion.

About 200 million years ago Australia was a part of Gondwana, the largest southern continent that included Africa, Antartica and South America. As Gondwana split up, Australia became isolated and has remained so far over 100 million years. The marsupials had entered Australia before isolation. So their evolution had been independent for over 100 million years.