Question

In a large, sexually reproducing population with random mating with respect to phenotype, the frequency of an allele changes from 20% to 60% across several generations. Based upon this change in allele frequency, the most likely cause of the change is

that the allele mutates readily.

that genetic drift is responsible for the increase in the allele’s frequency.

that the allele codes for a trait that is maladaptive in thepopulation.

that the allele codes for a trait that is adaptive in thepopulation.

Answer 1

In a large, sexually reproducing population with random mating with respect to phenotype, the frequency of an allele changes from 20% to 60% across several generations. Based upon this change in allele frequency, the most likely cause of the change is

that the allele codes for a trait that is adaptive in thepopulation.

Genetic drift (also known as allelic drift or the Sewall Wright effect after biologist Sewall Wright) is the change in the frequency of a gene variant (allele) in a population due to random sampling of organisms. The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces. A population's allele frequency is the fraction of the copies of one gene that share a particular form. Genetic drift may cause gene variants to disappear completely and thereby reduce genetic variation.

Adaptive evolution is shaped by the interaction of population genetics, natural selection and underlying network and biochemical constraints. Variation created by mutation, the raw material for evolutionary change, is translated into phenotypes by flux through metabolic pathways and by the topography and dynamics of molecular networks. Finally, the retention of genetic variation and the efficacy of selection depend on population genetics and demographic history. Emergent high-throughput experimental methods and sequencing technologies allow us to gather more evidence and to move beyond the theory in different systems and populations. Here we review the extent to which recent evidence supports long-established theoretical principles of adaptation.