Choices B, C, and D are all incorrect. These terms do not relate to the genetic information of a population.

The correct answer is A.
A gene pool consists of the sum of a population’s genetic material or genetic information.

a. gene pool

Most mutations are neutral, which means it has little effect on the organism. Some mutations are harmful when they decrease the fitness of an individual. However, if the mutation gives the individual an advantage on survival and reproduction, it is considered beneficial. Therefore, the answer is C.

c. beneficial

A polygenic trait is influenced by two or more genes, wherein the traits have a wide variety of phenotypes. Height, hair color, and skin color are examples of polygenic traits.

b. polygenic traits

A gene pool contains different types of alleles. The percentage or the number of times that an allele occurs in a particular gene pool is called allele frequency. When the allele frequency in a gene pool changes over time, this indicates that a population is evolving.

We can use the fur color in a rabbit population as an example. In this gene pool, there are two types of alleles: gray fur and white fur. The allele frequency for the gray fur is 60%, whereas the allele frequency for white fur is 40%.

The number of phenotypes for a certain trait is usually influenced by the number of genes that control the trait. It can either be a single-gene trait or a polygenic trait. A single-gene trait refers to a characteristic or a phenotype that is controlled by one gene. Each gene trait is influenced or controlled by two or three phenotypes. On the other hand, a polygenic trait is influenced by two or more genes, wherein the traits can have a wide variety of phenotypes.

Lateral gene transfer occurs when the genetic material is transferred between organisms. This is not the same as transferring the genes from parent to offspring. This process usually occurs in single-celled organisms such as bacteria and plasmids.

A gene pool contains different types of alleles. The percentage or the number of times that an allele occurs in a particular gene pool is called allele frequency. When the allele frequency in a gene pool changes over time, this indicates that a population is evolving. When evolution takes places, the combination of alleles or phenotypes in the population is changing and not the individual organism.

Choices A, C, and D are all incorrect. In directional selection, nature favors the individuals at one end of the curve. These individuals have a higher fitness when compared to the others. On the other hand, disruptive selection takes place when two extreme traits or phenotypes are favored by nature, while the average type has a difficulty in adapting to the new condition. This is shown by a curve that has two peaks.

The correct answer is B. A stabilizing selection takes place when individuals that are considered as average types are favored by nature. This is shown when the center of the curve is in the middle.

b. stabilizing selection

Due to the isolation of the smaller population among the original and larger population, such as the bottleneck effect or the founder effect, a genetic drift may happen by chance. This random change happens when a small population that carries an allele are able to reproduce more offspring than the other group. Eventually, this kind of allele becomes common in a particular population.

b. genetic drift

The founder effect occurs when a small subgroup of a population decides to migrate from one place to another. As a result, there are now changes in their allele frequencies that are different from the original species.

b. the founder effect

When natural selection takes place on a population that has single-gene traits, it may affect the allele frequencies and cause some changes in the frequency of phenotypes. For example, the gene for the lizard’s color has two alleles: yellow or brown color. When a predator is introduced into the environment, the yellow lizards are often eaten since they are more visible than the brown lizards when they are perched on tree branches. As a result, the population of yellow lizards would decline., Eventually, the frequency of the allele for yellow color will decrease and the frequency of allele for brown color would increase. This would result in a higher population of brown lizards on the next generation.

A stabilizing selection takes place when individuals that are considered as average types are favored by nature. This is shown when the center of the curve is in the middle. On the other hand, a disruptive selection takes place when two extreme traits or phenotypes are favored by nature, while the average type has a difficulty in adapting to the new condition. This is shown by a curve that has two peaks.

Genetic equilibrium is a condition that is characterized by constant allele frequencies in a particular population. Here are the five conditions that would help maintain the genetic equilibrium:

1. individual organisms must mate with others randomly
2. large population size
3. no migration to inhibit low gene flow
4. no mutation in the genes
5. low genetic variability to inhibit natural selection

Choices A, B, and D are all incorrect. These ideas refer to behavioral and geographical isolation mechanisms.

The correct answer is C. If two species reproduce offspring at different times, this isolating mechanism is called temporal isolation.

c. reproduce at different times

The term reproductive isolation is a mechanism that involves two populations that are no longer mating and producing offspring. As a result, the gene pool cannot spread and connect to other species.

b. reproductive isolation

In this graph, a disruptive selection in the rabbit population took place. When natural selection takes place on a population that has polygenic traits, it affected the average types and favored two distinct phenotypes. The two distinct phenotypes, which includes the white and dark brown rabbits, are characterized by the two peaks in the curve. On the other hand, the average type includes the rabbits that have a light brown color. These species are having difficulties in surviving and reproducing; hence, their population size is very small.

Factors such as geography, behavior, and time can separate populations and trigger reproductive isolation. In geographic isolation, the population is separated by a physical barrier, such as mountains, rivers, and oceans. In behavior isolation, behavioral patterns set differences among species in terms of their interbreeding methods such as courtship rituals and reproductive strategies. On the other hand, time acts as an isolating mechanism if two species reproduce offspring at different times. This event is called temporal isolation.

The geographic barriers that result in the geographic isolation of species include natural land and water features such as rivers, oceans, and mountains.

Hox genes, which are a group of related genes that code proteins, influence the organism’s body development by controlling the size and shape of the fingers, toes, arms, legs, and other body parts. Small changes in these genes during the development can create significant differences in the appearance of such body parts when they become adults.

d. Hox genes

Through the help of molecular clocks, which show the DNA mutation rate, scientists can estimate the amount of time that has passed since the two species shared a common ancestor. According to them, the mutation rate is compared to seconds ticking on a clock. More importantly, this method can show how these two organisms are closely related.

c. DNA mutation

Homologous chromosomes receive an extra copy of a gene when there is an unequal swapping or exchange of DNA during a cross-over in meiosis. When a gene is duplicated, the original gene may continue to perform its old role, whereas the duplicated copy of the gene may start to mutate and perform a new role.

Evo-devo refers to evolutionary developmental biology. It studies and focuses on the developmental processes of organisms in order to know their evolutionary origin. This discipline is related to evolution because it helps us understand how the developmental processes and phenotypes of organisms have evolved due to natural selection.

Neutral mutations refer to changes in the genes that are considered as neither beneficial nor harmful to an organism’s fitness. One example of a neutral mutation is the eye color. This is a neutral mutation because it does not have a positive or a negative effect to the organism’s ability to survive and reproduce.

In most cases, mutations affect the phenotype and cause genetic variation by making a new DNA sequence, which creates a new allele. However, if the DNA of a person contains 300 mutations, there is a huge possibility that the number of the distinct effects in phenotype are fewer than 300.

We can expect that some mutations are not passed on the offspring. This can happen in many situations, particularly when the mutations occur in non-reproductive cells. On the other hand, some mutations don’t have any noticeable effect on the individual’s phenotype. This occurs when the mutation occurs in a stretch of DNA that has no function or a noncoding region.

A single-gene trait refers to a characteristic or a phenotype that is controlled by one gene. In each gene trait, it can be controlled by two or three phenotypes. For example, the gene for the guinea pig’s color has two alleles. One allele is responsible for the white color and the other one is for the black color. There are only two phenotypes for this trait: white or black color.

Aside from the geographic barriers, factors such as behavioral patterns and time can separate populations and trigger reproductive isolation and creation of new species. In addition, changes in the gene pool and ecological competition can also lead to speciation.

According to the Hardy-Weinberg principle, allele frequencies remain in genetic equilibrium unless an event or a condition causes them to change. In order for a population to maintain genetic equilibrium, the individuals must mate randomly with other individuals. However, if individuals undergo sexual selection, wherein they pick mates based on a certain trait, the frequency of that trait will surely increase. This event would disrupt the genetic equilibrium.

The speciation in the Galapágos Islands was caused by geographic isolation. When the finches arrived in the different islands of Galápagos, they were isolated and they do not share the common gene pool anymore because they rarely flew over open water. Even when some flew across from one island to another, their differences in mating rituals, ecological competition, and other behavioral patterns have made interbreeding and coexisting in one habitat difficult. Because of this, the gene pools of the two populations remained isolated. As a result, populations of finches in the different islands evolved separately and eventually, they have become separate species.

If a highway is built through the forest and divides it in half completely, it causes habitat fragmentation and it creates a barrier that would isolate the two groups of pine trees. Since a small population is susceptible to genetic drift, the genetic makeup of the two groups of pine trees would randomly change. This becomes the main driving force of evolution.

Hox genes, which are a group of related genes that code proteins, influence the organism’s developmental processes by controlling head-to-tail organization of many organisms such as the size and shape of the fingers, toes, arms, legs, and other body parts. Small changes in these genes during the development can create significant differences in the appearance of such body parts when they become adults.

Moreover, these genes are considered homologous to the ancestor of a particular organism. In this case, scientists study the coding of proteins in the embryo of animals since these genes give us clues about the origin and evolution of body plans between organisms.

The DNA of two species are used to trace their evolutionary relationship on a molecular level. Since living things are able to pass on their genetic information to their offspring, the mutations in the genes are also passed into them. Once the mutation is passed into the next generation, evolution takes place. In this case, by studying the DNA or the genetic information of organisms, scientists can determine how species diverged from their ancestors.

Yes, the gene pool for the turkey’s feather color is changing due to a directional selection on polygenic traits. Since nature favors the trait of black feathers more than the bronze feathers, it becomes more common; hence, the evolution moves in one direction.

When nature favors one trait over another, a natural selection takes place. In this process, the stronger species survive and they change the balance in the population of species.

In the case of the turkeys, nature favors the turkeys with black feathers over the ones with bronze feathers. As a result, the frequency of the black feather trait becomes more common in the population.

If turkeys are domesticated, they are often isolated from the other species that live in the wild. This causes the genetic pool to change due to the isolation of the small population as they move into a new habitat. The changes in the genetic makeup are usually different when the turkeys from the farms are compared to the turkeys that live in the wild. Therefore, this event gives rise to the diversity between the two populations (wild and domesticated).