Which of the following evolutionary forces tends to remove genetic variation from a population

In many birds males display to females at perch sites.  Females visit multiple perch sites, watch the displays, and then mate with one of the males.  What type of evolutionary force is acting on male displays? Group of answer choices A. directional (natural) selection B. intersexual selection C. stabilizing (natural) selection D. disruptive (natural) selection E. intrasexual selection

Atlantic cod have experienced decades of overharvesting. As a result, the age of maturity of Atlantic cod populations have decreased, so that fish today reach sexual maturity early – at significantly smaller sizes than fish 50 years ago. From this, we can interpret that populations of Atlantic cod are experiencing. A. Directional selection B. frequency dependent Selection C. Disruptive Selection D. Genetic Drift E. Stabilizing Selection 2. In 1958, the average age to sexual maturity in the Atlantic cod population was 7.0 years. In 1959 there was a particularly large harvest of the Atlantic cod population. Fish that bred successfully that year had an average age of sexual maturity of 6.0 years. The difference between these values represents A. Mutation rate B. Selection Differential C. Response to selection D. Heritability   3. The difference in age at sexual maturity between the offspring of the fish that survived the harvest in 1959 (i.e. 6.2 years) and the population average before…

Given that selection cannot favor traits that lower fitness, what might cause a population to move down from a fitness peak in Sewall Wright’s “adaptive landscape”? (Pick one answer)   A. Inverse frequency dependent selection   B. Large population size   C. Overdominant selection   D. Genetic drift   E. All of the above