How can harmful alleles be maintained in a population?

How can natural selection maintain harmful alleles in a population?

How can natural selection maintain harmful alleles in a population? Natural selection can only select against phenotypes. If the dominant phenotype is selected for, heterozygous individuals will retain the recessive allele in the population.

How do you maintain genetic variation in a population?

Finally, changing patterns of selection over time or space can help to maintain genetic variation in a population. If selection patterns fluctuate over time, different alleles or genotypes may enjoy greater fitness at different times. The overall effect may be that both alleles persist in a population.

How can a harmful trait such as Huntington’s disease remain in a population?

Research on the evolutionary genetics of this disease suggests that there are two main reasons for the persistence of Huntington’s in human populations: mutation coupled with weak selection. The diagram at left shows how the Huntington’s allele is passed down.

Why natural selection keep a harmful allele in a gene pool?

Here’s how natural selection can keep a harmful allele in a gene pool: … Heterozygotes (AS) with the sickle-cell allele are resistant to malaria. Therefore, they are more likely to survive and reproduce. This keeps the S allele in the gene pool.

IT IS INTERESTING:  What does the Telocentric chromosome looks like?

Why would a harmful allele be maintained in a population?

Deleterious alleles may also be maintained because of linkage to beneficial alleles. The inability of natural selection to eliminate diseases of aging is a reminder that fitness — success in producing progeny, or in contributing genes to the population gene pool — is not equivalent to the absence of disease.

How is variation maintained population quizlet?

How is variation generated in a population? How is it maintained? Through sexual or gene mutation. It is maintained through the random arrangement found in sexual reproduction.

What causes genetic variation in a population?

Mutations, the changes in the sequences of genes in DNA, are one source of genetic variation. Another source is gene flow, or the movement of genes between different groups of organisms. Finally, genetic variation can be a result of sexual reproduction, which leads to the creation of new combinations of genes.

How does gene fixation occur?

Fixation can refer to a gene in general or particular nucleotide position in the DNA chain (locus). In the process of substitution, a previously non-existent allele arises by mutation and undergoes fixation by spreading through the population by random genetic drift or positive selection.

What does it mean for an allele to reach fixation?

A gene has achieved fixation when its frequency has reached 100% in the population. At that stage, all individuals are homozygous for that allele until a new mutation arises. A gene may be taken to fixation by selection or genetic drift. Populations often maintain polymorphism at a locus.