Question

Discuss the mechanisms of evolution

Answer 1

There are five main mechanisms of evolution: mutation, genetic drift, gene flow, non-random mating, and natural selection.

Mutation is the source of new alleles. We cannot predict when or in which individual a particular gene will mutate. We can predict an average mutation rate, the probability that a mutation will occur in a given interval, for a species.

Genetic drift is a random change in allele frequencies over time, brought about by chance. Genetic drift is pronounced when a few individuals rebuild a population or start a new one, such as occurs

after a bottleneck – a drastic reduction in population size brought about by severe pressure.

Individuals of the same species do not always stay in the same geographic area, or in the same population. A population can lose alleles when individuals leave it permanently, an act called emigration. A population gains alleles when individuals permanently move in, an act called immigration. Gene flow, the movement of alleles among populations, occurs in both cases. Gene

flow is a microevolutionary process that counters the diversifying effects of mutations, natural selection, and genetic drift in a population.

A common form of non-random mating is inbreeding. It refers to matings between relatives. Inbreeding leads to a decrease in the frequency of heterozygotes. The most intense form of inbreeding is self-fertilization, which may occur in hermaphroditic organisms.

Natural selection is differential survival and reproduction among individuals of a population that vary in the details of shared traits. Some traits prove more adaptive than others in prevailing environmental conditions. Natural selection influences all levels of biological organization.