Question

When a gene locus is not in Hardy-Weinberg equilibrium, we can conclude that some force of evolution is acting upon this locus to cause evolutionary change. What additional lines of evidence are used to provide us with clues about the likelihood of particular forces of evolution being responsible for the observed deviation from HWE? Offer several examples of the patterns in allele and genotype frequencies that one would expect under various forces of evolution.

Answer 1

Deviations from Hardy-Weinberg equilibrium indicate evolutionary forces at play, such as natural selection, genetic drift, mutation, and gene flow. These forces cause changes in allele and genotype frequencies, offering clues about the mechanisms of evolution.

Step-by-step explanation:

When a gene locus is not in Hardy-Weinberg equilibrium (HWE), it suggests that evolutionary forces are present. To discern which forces might be responsible, scientists look for patterns in allele and genotype frequencies. For instance, an increase in allele frequency due to natural selection will be seen if the allele confers a selective advantage. Conversely, random changes in allele frequencies due to genetic drift are expected in small populations, potentially leading to a loss of genetic variation.

Mutation as a force introduces new alleles and changes frequencies incrementally over generations. Gene flow, on the other hand, involves the movement of alleles between populations, which can introduce new genetic material and alter allele frequencies. Nonrandom mating affects genotype frequencies but not the alleles directly unless it influences reproductive success. Allele frequencies under these evolutionary pressures provide insights into the types and intensities of forces at work.