Final answer:
Positive selection is more likely to occur at genes and specific codons within those genes that are associated with adaptive traits. Outlier analyses and single nucleotide polymorphism (SNP) analysis are methods to detect loci under positive selection by comparing genetic divergence and allele frequencies.
Step-by-step explanation:
Positive selection refers to the process in which certain genetic variants or alleles are favored and increase in frequency within a population over time. In terms of loci, positive selection is more likely to occur at genes and specific codons within those genes that are associated with adaptive traits. For example, if a particular gene is involved in providing resistance to a disease, positive selection would favor alleles that confer this resistance, leading to an increase in their frequency within the population.
One way to identify loci under positive selection is through outlier analyses. These analyses compare the genetic divergence of a gene with the divergence of neutral genetic markers, such as microsatellites, scattered throughout the genome. If the divergence at a specific gene is significantly higher or lower than the neutral markers, it suggests that positive selection may have acted on that gene.
Another method to detect loci under positive selection is through single nucleotide polymorphism (SNP) analysis. By comparing the frequency of different alleles at specific loci between individuals with different traits, researchers can identify loci that are associated with adaptive differences.