Question

In order to build a longitudinal dataset, data of adult finches Geospiza fortis living on one of the Galapagos islands were collected. The beak shape data collected between $1971-2001$ are shown in the graph

Study the graph and select the correct statement

• A. The fluctuating direction in the beak shape is most probably due to change in the environment
• B. The graph as a whole does not indicate evolutionary change in the beak shape as the time interval is too small and evolution requires thousands of years to occur
• C. The graph indicates that the beak shape may lead to convergent evolution in the finches of Galapagos islands
• D. The change in any phenotypic character requires selection to alter the expression of large number of genes in coordinated fashion. Hence, it is unlikely that change in the beak shape depicted in the graph is a result of evolution

Answer 1

Answer: (A)

The diversity in beak shape is most probably due to changes in environment which lead to natural selection and gene flow among species. The graph does indicate evolutionary change. It has been shown that evolution can occur with surprising speed; as fast as those resulting from artificial selection. The selection in case of finches was strong and the populations evolved in a matter of generations.The Galapagos finches afford an excellent example of adaptive radiation. It is assumed that a stock of ancestral finches reached the islands from the mainland and then in the absence of much competition, evolved to fill many of the empty ecological niches. There a change in a phenotypic character can be attributed to alteration in the expression of one to several genes. Thus, the change in beak shape can be attributed to evolution