Question

Which of the following statements is correct? a. Genetic drift occurs only in small populations. b. Inbreeding increases genetic diversity. c. Gene flow can reintroduce alleles into a population.

Short answer

Statement 'c' is correct: Gene flow can reintroduce alleles into a population.

Step-by-step solution

Understanding Genetic Drift

Genetic drift is a random process that can cause changes in allele frequencies in a population. While it is particularly pronounced in small populations due to the smaller pool of alleles, it can theoretically occur in large populations as well. Therefore, saying it occurs only in small populations is incorrect.

Evaluating Inbreeding

Inbreeding refers to the mating of closely related individuals, which often results in a decrease in genetic diversity due to the increase in homozygosity of alleles. This concentration of similar alleles generally reduces genetic variability in the population, meaning inbreeding does not increase genetic diversity.

Understanding Gene Flow

Gene flow is the transfer of alleles or genes from one population to another. It occurs when individuals from different populations interbreed, which can introduce new alleles into the population. Therefore, gene flow can indeed reintroduce alleles into a population, making this statement correct.

Key concepts

Genetic Drift

Genetic drift is a fascinating concept in the field of population genetics. It's essentially a random process, meaning that it does not follow a predictable pattern like natural selection. The key point to understand about genetic drift is that it causes allele frequencies—variations of genes within a population—to change over time purely by chance.

While it can happen in any population, its effects are most commonly observed in small populations. This is because there are fewer individuals to "average out" the randomness, which means certain alleles might become more common simply by chance, while others might disappear. In larger populations, the sheer number of individuals can often mitigate these random fluctuations, making genetic drift less noticeable.

Regardless of population size, genetic drift can lead to a lack of genetic variation over time. This phenomenon can reduce a population's ability to adapt to new environmental conditions, as the genetic repertoire is limited. Understanding the role of genetic drift emphasizes the importance of preserving biodiversity, especially in species with declining population sizes.

Inbreeding

Inbreeding is essentially the mating of individuals who are closely related genetically. This doesn't introduce any new genetic material into the population, as the parents share many of the same alleles. This unique mating system has some profound effects on genetic variance.

One of the primary consequences of inbreeding is an increase in homozygosity, where offspring inherit the same alleles from both parents. This can lead to a reduced genetic diversity because there is less variability in the alleles being passed on to the next generation. Reduced genetic diversity can limit a population’s ability to adapt to environmental changes because there are fewer variations to select from if conditions change.

Additionally, inbreeding can lead to the expression of deleterious recessive traits that can negatively affect the health and survival of individuals. This is why understanding and monitoring inbreeding is crucial, especially in conservation efforts, where maintaining healthy and viable populations is a primary goal.

Genetic Diversity

Genetic diversity refers to the total number of genetic characteristics within a species. It's one of the key factors that can influence a population's ability to adapt to changing environments. High genetic diversity means greater variation in traits among individuals, which can enhance a population's resilience to challenges such as disease outbreaks or climate change.

There are several factors that can affect genetic diversity, including mutation, gene flow, genetic drift, and natural selection. Among these, gene flow is particularly important because it involves the movement of alleles between populations. This can introduce new alleles and increase genetic variability, promoting adaptability.

Maintaining genetic diversity is critical for the health and survival of populations, as it allows them to evolve and cope with environmental shifts. Conservation biologists often aim to preserve or increase genetic diversity in endangered populations to ensure their long-term survival.