Darwin observed that members of a population vary in their traits. We now know that this variability is generated by: random DNA mutations adaptation of DNA directional selection allopatric speciation

In a population of birds, the climate becomes colder over time. Birds with larger bodies and thicker feathers survive better and produce more offspring than those with smaller bodies and thinner feathers. Which type of selection is occurring in this scenario? Stabilizing selection Disruptive selection Directional selection Frequency-dependent selection

The next five questions (questions 11-15) are related to each other. Read all of the scenarios very carefully and in order and select the correct answer. A population of 10,000 blue grasshoppers lives on an island. Most members of the population live among the grasses because they are not very good climbers. Some grasshoppers live in the trees because they are good climbers. One year, a short-legged mouse arrived at the island and ate all grasshoppers within its reach, thus totally wiping out the grasshoppers living in the grasses. Luckily, those grasshoppers that were good climbers were spared. This story is an example of Gene Flow Founder Effect C Natural Selection Genetic Drift

Select all of the processes that can cause changes in allele frequencies. gene flow large population size genetic drift natural selection mutation

With which statement would Darwin most likely have agreed? *       Competition among individual species causes heritable variations       Variations are caused by Natural selection       Organisms best adapted to a particular environment are the most likely to reproduce.       No answer       Survival of any species is proportional to the inheritance acquired characteristics.

Human adult males generally have deeper voices than do adult females, which is the direct result of higher levels of testosterone causing the enlargement of the larynx. If one excludes the involvement of gender in the situation, then the pattern that is apparent in the fossil record is most similar to one that should be expected from what type of selection? directional selection stabilizing selection asexual selection disruptive/diversifying selection

In a population of birds, those with either very long or very short beaks are more successful at obtaining food resources than those with medium-sized beaks. Over time, the two extremes of beak size become more prevalent in the population. Which type of selection is occurring, and what might be the long-term consequence for this population? oooo Disruptive selection; speciation Directional selection; speciation Frequency-dependent selection; no change in the population Stabilizing selection; no change in the population

Population divergence occurring as a result of females in a species consistently choosing males of a particular color is an example of     ecological speciation     Haldane's Rule     genetic drift     sexual selection

There are two major mechanisms that help populations evolve. The first is Natural Selection. The second is Prezygotic Isolation Genetic Drift Directional Selection Independent Assortment

The relatively high percentage of individuals in parts of Africa who are heterozygous for the sickle cel trait is an example of founder effect natural selection natural selection and heterozygote advantage genetic drift heterozygote advantage