Answer:
See explanations
Explanation:
success (how many offspring an organism leaves in the next generation, relative to others in the group).
Natural selection can act on traits determined by alternative alleles of a single gene, or on polygenic traits (traits determined by many genes).
Natural selection on traits determined by multiple genes may take the form of stabilizing selection, directional selection, or disruptive selection.
Introduction
We've already met a few different mechanisms of evolution. Genetic drift, migration, mutation...the list goes on. All of these mechanisms can make a population evolve, or change in its genetic makeup over generations.
But there's one mechanism of evolution that's a bit more famous than the others, and that's natural selection. What makes natural selection so special? Out of all the mechanisms of evolution, it's the only one that can consistently make populations adapted, or better-suited for their environment, over time.
You may have already seen natural selection as part of Darwin’s theory of evolution. In this article, we will dive deeper – in fact, deeper than Darwin himself could go. We will examine natural selection at the level of population genetics, in terms of allele, genotype, and phenotype frequencies.
Quick review of natural selection
Here is a quick reminder of how a population evolves by natural selection:
Organisms with heritable (genetically determined) features that help them survive and reproduce in a particular environment tend to leave more offspring than their peers.
If this continues over generations, the heritable features that aid survival and reproduction will become more and more common in the population.
The population will not only evolve (change in its genetic makeup and inherited traits), but will evolve in such a way that it becomes adapted, or better-suited, to its environment.
Natural selection can cause microevolution
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). When a phenotype produced by certain alleles helps organisms survive and reproduce better than their peers, natural selection can increase the frequency of the helpful alleles from one generation to the next – that is, it can cause microevolution.
