Question

When a species occupirs a wide area, its phenotyprs usually vary actoss its geographic range. This variation results from different evolutionary processes in different environments.

Contrast adaptive evolution from non-adaptive evolution and give an example of how each can generate phenotype variation among population of a species

Answer 1

Evolution is defined as the change in the heritable characteristics which are present in the population. Evolution may occur through natural selection, sexual selection, artificial selection, genetic drift, mutation pressure, or migration. Adaptive evolution refers to the evolutionary changes in an organism which makes the organism suitable for its habitat. These evolutionary changes result in an increased chance of survival and reproduction. These changes are the organism's adaptive traits which enable the particular organism to fit into an environment. They arise as a result of natural selection. Example-adaptive evolution in finches. A population of finches evolved into three separate species through natural selection by adapting to various selection pressures. Each of the three finches has a beak which is adapted to its life history and diet.

While non-adaptive evolution refers to any change in allele frequency which does not lead the population to become more adapted to its environment. These changes are due to the mutation, genetic drift, and gene flow which occurs when the allele frequencies in a population change randomly. Example- the African rhinoceros has two horns while the Asian rhino has only one.