Question

Based on the phenomenon represented by the given diagram, choose the correct statement from the following.

• A. The finches on the Galapagos islands prove an evolution due to mutation.
• B. A rapid decline was observed in the population of finches on the islands due to competition among the species.
• C. This phenomenon is an example of convergent evolution, which is similarly observed between the Australian marsupials and placental mammals.
• D. The original insectivorous finches evolved into seed-eating and vegetarian finches, eventually changing the shape of their beaks according to their food habits.

Answer 1

Answer: (C)

The finches of Galapagos Islands provided evidence in favor of adaptive radiation. They are known as Darwin's finches, as they were observed by Darwin while he visited the island. He discovered that different varieties of the finches which evolved in the same island. The variety ranged from the original seed-eating features to other forms with altered beaks. These modifications enabled them to become insectivorous and vegetarian finches. This process of evolution of species in a given geographical area which starts at a particular point and radiates to other areas of geography is called adaptive radiation.
Another example is Australian marsupials. A number of marsupials, each different from the other evolved from an ancestral stock, but all within the Australian island continent. When more than one adaptive radiation appeared to have occurred in an isolated geographical area (representing different habitats), one can call this convergent evolution. Placental mammals in Australia also exhibit adaptive radiation in evolving into varieties of such placental mammals each of which appears to be ‘similar’ to a corresponding marsupial (e.g., Placental wolf and Tasmanian wolf-marsupial).