Natural selection is an inevitable process that selects for the fitness of organism with different traits.The common reference to 'survival of the fittest' simply refers to adaptation of a species through through extinction of the less fit genotype.Mutations accumulate in the genotype of organisms,resulting in descent with modification,a situation where the genome of the descent is not homologous to that of the parent.These changes in the genome may result in phenotypic variations,which in some cases lead to speciation.Since natural selection only selects for fitness,useless traits that do no negatively impact fitness is not selected against; humans,for example,still possesses a vestigial tail despite of its obvious inutility.Speciation is not to be confused with genetic recombination,in which case the same genetic information is rearranged within a population; speciation is the result of novel alleles due to various types of mutations.Small populations,which may have been created by genetic drift,is often exposed to the issue to reproductive isolation,otherwise known as inbreeding.This reduces the variability in the population,and reduces the viability of the population as a whole.
你学什么的?怎么有这种题?