Bio Test 3 (Part 4)

The sharp reduction of the gene pool and population numbers through a severe epidemic is an example of the bottleneck effect. This occurs when a population is drastically reduced in size, leading to a significant loss of genetic diversity. As a result, the surviving individuals have a limited gene pool, which can impact the population's ability to adapt to environmental changes. This phenomenon is a key concept in evolutionary biology and can have long-lasting effects on the genetic composition of a population.

The correct answer is "inherited genes that made it resistant to the pesticide." This is because resistance to a pesticide is usually due to genetic variations that are passed down from one generation to another. Insects with these inherited genes are better able to survive and reproduce in the presence of the pesticide, leading to an increase in the resistant population over time.

Sexual dimorphism refers to the physical differences between males and females of the same species. These differences can include size, coloration, and other characteristics that are related to reproduction and mate selection. Polymorphism refers to the occurrence of different forms or variations within a species, which may or may not be related to sexual differences. The dioecious condition refers to the separation of sexes into distinct male and female organisms. Sexual selection refers to the process by which certain traits are favored and passed on to the next generation due to their attractiveness to potential mates. Primary sexual characteristics are the anatomical structures directly involved in reproduction. Therefore, sexual dimorphism is the most appropriate term to describe the difference in appearance between male and female individuals.

The correct answer is "natural selection of forms that expressed genes for resistance." This explanation is based on the concept of natural selection, which states that organisms with traits that provide an advantage for survival and reproduction are more likely to pass on their genes to the next generation. In this case, when DDT was first introduced, insects that had genes for resistance to DDT were more likely to survive and reproduce, leading to the development of resistance in the insect population over time.

In most species that exhibit sexual dimorphism, the selection of a mate is the responsibility of the female. This means that females have the power to choose their mates based on various factors such as physical traits, behavior, or resources provided by the male. This is often observed in species where males compete with each other for the attention and favor of females, and females have the final say in selecting the most suitable mate.

Male northern sea lions are nearly twice the size of females because males compete to mate with females. This is a common phenomenon in many animal species where males develop larger bodies or other physical traits to gain an advantage in competing for mates. In the case of northern sea lions, larger males are more successful in competing for females, which leads to a size difference between the sexes. This competition for mates drives the evolution of larger male size in order to increase reproductive success.

As the trees of England become less sooty due to pollution controls on factories, the environment becomes less favorable for dark moths. Dark moths are more visible and easier for predators to spot on cleaner trees, which makes them more likely to be eaten. On the other hand, light-gray moths are better camouflaged against the lighter-colored trees, which gives them an advantage in survival. Therefore, fewer dark moths should survive, and more light-gray moths should survive.

The given information states that male mallards have distinct physical characteristics (emerald green head feathers and metallic blue patches) while female mallards have less noticeable features (drab, brown feathers). This suggests that there is a difference in appearance between males and females, which could lead to sexual isolation. Sexual isolation refers to the situation where individuals of different sexes have different traits or behaviors that prevent them from successfully mating with each other. In this case, the distinct physical characteristics of male and female mallards could lead to a reduced likelihood of successful mating, indicating sexual isolation.

The genetic variability in the North American population of starlings is reduced relative to that in Europe because the North American population is derived from a small founder population. This means that only a limited number of individuals were initially introduced into North America, resulting in a smaller gene pool and less genetic diversity compared to the larger and more diverse population in Europe.

Genetic drift refers to the random fluctuations in allele frequencies within a population. It occurs more prominently in smaller populations where chance events can have a greater impact on the gene pool. As population size decreases, genetic drift becomes more influential because there are fewer individuals to contribute to the next generation's gene pool. In larger populations, gene flow, mutation rates, the number of heterozygous loci, and random mating have a relatively smaller effect on allele frequencies compared to genetic drift.

Gene flow refers to the transfer of genetic material from one population to another through migration or interbreeding. This process can lead to increased genetic similarity between adjacent populations as individuals from one population introduce new genetic variations to another population. This can result in the spread of beneficial traits and the homogenization of gene pools, making adjacent populations more similar. Therefore, the correct answer is "makes adjacent populations more similar."