In directional selection, a population’s genetic variance shifts toward a new phenotype when exposed to environmental changes. Diversifying or disruptive selection increases genetic variance when natural selection selects for two or more extreme phenotypes that each have specific advantages.
How does selection act on phenotype?
Natural Selection Operates on Phenotype
The traits that an individual expresses, its phenotype, are what will give that individual an advantage or disadvantage in the struggle to survive and reproduce. Natural selection operates on phenotype.
How does natural selection affect phenotypes?
Natural selection on single-gene traits can lead to changes in allele frequencies, causing changes in phenotype frequencies. Natural selection on polygenic traits can affect the relative fitness of phenotypes thereby producing directional, stabilizing, or disruptive selection.
What causes phenotype to change?
The phenotype may change constantly throughout the life of an individual because of environmental changes and the physiological and morphological changes associated with aging. … Three types of natural selection, showing the effects of each on the distribution of phenotypes within a population.
What is the source of new phenotypes?
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.
Does selection act on genotype or phenotype?
Natural selection acts on an organism’s phenotype, or observable features. Phenotype is often largely a product of genotype (the alleles, or gene versions, the organism carries).
Why does natural selection act on phenotype rather then genotype?
While it may make sense that natural selection would act on the genotype, an organism’s genetic make-up, the action actually occurs on the phenotype, an organism’s physical traits. Having a secret genetic ability to produce blue-eyed offspring doesn’t matter one bit to your potential mate.