Question

Using relevant vocabulary, explain the concept of natural selection and how it led to changes in the frequencies of beak sizes within this population over generations.

Answer 1

Natural selection is a key mechanism to evolution . The theory of evolution by natural selection was proposed by Charles Darwin . In the process of natural selection , heritable variations in the individuals enables better reproduction , survival & leave greater number in progeny & later pass on the traits to the next generation. Because of the variations due to mutation or recombination during the process of gametogensis or it can be because of the gene flow/genetic drift which results in changes in frequency of the genes & alleles in future generations . In all the population of an individual variation exists . Natural selection totally depends upon the environment . It doesn't favour traits which are inherently superior . It only favour traits which are beneficial for an individual in a specific environmental conditions because it can be possible that tge traits which are helpful in one environment & can be harmful in another. Later the George Mendal's " theory of inheritance" & "the theory of evolution by natural selection " by Darwin combined together & gave birth to modern population genetics .

The Darwin's finches illustrated that how rapid & effective natural selection can be . In 1977 , on Daphne Major there was a major drought & it effected the plants . The plants on the island produced no seeds or fewer seeds . The ground finches depends on the seeds for food & because of the shortage of seeds the population drastically reduced in just few years .

The Grants research group have observed that the population of finches had recovered but the size of the beak was larger than normal the reason for this was during drought , only the large seeds with husks were available & the small seeds were rare . Because of this only large birds who have large beak were able to crack & open the husks and eat the seeds . The small birds with small beak were not able to do this therefore, they starved . Because of this death pattern the finches population & size of the beaks rapidly changed . In these finches, the size of beak is heritable, which means that the adults who have large beak passes on the traits of large beak size to the next generations .