True or false? (if false, replace word in *here*)
1) The random changes of allele frequencies associated with genetic drift frequently lead to a *gain* in genetic diverse.
2) *sexual selection* helps maintain the Hb^a/Hb^s heterozygous conditions in humans.
3) bottleneck and founder effects are examples of *genetic drift*.
4) *gene flow* counteracts the effect of mutation, natural selection. And genetic drift.
5) the high rate of Ellis-van creaked syndrome inamish populations is due to gene flow.
6) inbreeding *increases* genetic diversity of a population.
1) True
2)natural selection
3)true
4)??
5)False
6)Decreases (you have the same # of different genes staying within a small area((inbreeding))
False. The correct word is "loss" instead of "gain."
False. The correct term is "balanced polymorphism" instead of "sexual selection."
True.
False. The correct word is "enhances" instead of "counteracts."
False. The correct term is "genetic drift" instead of "gene flow."
False. The correct term is "decreases" instead of "increases."
True or false? (if false, replace word in *here*)
1) The random changes of allele frequencies associated with genetic drift frequently lead to a *gain* in genetic diversity.
Answer: False. The random changes of allele frequencies associated with genetic drift frequently lead to a *loss* in genetic diversity. Genetic drift refers to the random fluctuations in allele frequencies in a population that can lead to the loss of genetic variation over time.
To understand why genetic drift leads to a loss in genetic diversity, you can consider the process. Genetic drift occurs in small populations where chance plays a significant role in determining which individuals reproduce and pass on their alleles to the next generation. Due to random events, certain alleles can become more or less common in subsequent generations, leading to a reduction in the overall genetic diversity of the population. This is because some alleles may be lost entirely, while others may become fixed (present in all individuals) within the population.
2) *sexual selection* helps maintain the Hb^a/Hb^s heterozygous conditions in humans.
Answer: False. *Natural selection* helps maintain the Hb^a/Hb^s heterozygous conditions in humans, not sexual selection. The Hb^a/Hb^s heterozygous condition refers to the presence of both the sickle cell allele (Hb^s) and a normal hemoglobin allele (Hb^a) in individuals, which provides a selective advantage in regions where malaria is prevalent.
To understand why natural selection, rather than sexual selection, helps maintain the Hb^a/Hb^s heterozygous conditions in humans, you need to consider the impact of malaria. Individuals who are heterozygous for the sickle cell allele (Hb^a/Hb^s) have a greater resistance to malaria compared to those who are homozygous for either the sickle cell allele (Hb^s/Hb^s) or the normal hemoglobin allele (Hb^a/Hb^a). As a result, individuals with the Hb^a/Hb^s genotype have a selective advantage in regions with malaria since they are less likely to develop severe cases of the disease. This selective advantage leads to the preservation of the Hb^a/Hb^s heterozygous genotype in populations exposed to malaria.
3) Bottleneck and founder effects are examples of *genetic drift*.
Answer: True. Bottleneck and founder effects are examples of *genetic drift*. Both involve a reduction in population size and the subsequent loss of genetic variation.
To understand how bottleneck and founder effects are examples of genetic drift, let's define each:
- Bottleneck effect: This occurs when a population undergoes a drastic reduction in size, usually due to a catastrophic event like a natural disaster or disease outbreak. The surviving individuals are a random subset of the original population and may not represent the original genetic diversity. As a result, the new population that emerges from the bottleneck has reduced genetic variation compared to the original population.
- Founder effect: This happens when a small group of individuals separate from a larger population and establish a new population in a different geographic area or habitat. The founding population is usually not representative of the original population in terms of genetic diversity. As a result, the new population derives its genetic composition from the small group of founders, leading to a loss of genetic variation.
Both bottleneck and founder effects are essentially random events that can cause significant changes in allele frequencies within a population. These effects illustrate how genetic drift can lead to a reduction in genetic diversity over time.
4) *Gene flow* counteracts the effect of mutation, natural selection, and genetic drift.
Answer: True. *Gene flow* counteracts the effect of mutation, natural selection, and genetic drift. Gene flow refers to the transfer of genetic material (alleles) between populations as a result of migration or interbreeding.
To understand how gene flow counteracts the effects of mutation, natural selection, and genetic drift, consider the following:
- Mutation: Gene flow can introduce new alleles into a population, increasing genetic variation. This counters the potential loss of genetic diversity caused by mutations since new alleles can be introduced from other populations.
- Natural selection: Gene flow can bring advantageous alleles to a population, allowing them to spread more rapidly through interbreeding. It can also prevent isolated populations from undergoing independent selection events, thus maintaining genetic diversity across populations.
- Genetic drift: Gene flow can reduce the impact of genetic drift by introducing new alleles and preventing genetic differentiation between populations. It can help offset the effects of random fluctuations in allele frequencies and maintain genetic diversity.
Therefore, gene flow is considered an important evolutionary force that can counteract the negative effects of mutation, natural selection, and genetic drift on genetic diversity within and between populations.
5) The high rate of Ellis-van Creveld syndrome in Amish populations is due to gene flow.
Answer: False. The high rate of Ellis-van Creveld syndrome in Amish populations is not due to gene flow. It is the result of a genetic founder effect, where a small group of founders who carried the rare Ellis-van Creveld syndrome allele established the Amish population.
To understand how the high rate of Ellis-van Creveld syndrome in Amish populations is due to a genetic founder effect, consider the following:
- A founder effect occurs when a small number of individuals establish a new population, and their genetic composition is not representative of the original population.
- In the case of the Amish populations, a few individuals who carried the Ellis-van Creveld syndrome allele were part of the founding group. As a result, the syndrome became more prevalent within the population due to the limited genetic diversity introduced by the founders.
Gene flow refers to the transfer of genetic material between populations, which can increase genetic diversity. However, in the case of the high rate of Ellis-van Creveld syndrome in Amish populations, the cause is the founder effect rather than gene flow.
6) Inbreeding *increases* genetic diversity of a population.
Answer: False. Inbreeding *decreases* genetic diversity of a population. Inbreeding refers to the mating between individuals who share a close genetic relationship, such as closely related relatives.
To understand why inbreeding decreases genetic diversity, consider the following:
Inbreeding increases the likelihood of mating between individuals who have similar alleles, including harmful recessive alleles. As a result, the frequency of harmful recessive alleles in the population increases, potentially leading to a higher incidence of genetic disorders and reduced overall fitness.
In contrast, outbreeding, which involves mating between individuals who are less closely related, promotes genetic diversity. Outbreeding increases the chances of introducing new alleles into a population and reduces the risk of harmful recessive alleles being expressed.
Therefore, inbreeding is generally associated with a decrease in genetic diversity, while outbreeding or mating between less closely related individuals promotes genetic diversity in a population.