Problem 9 - Biology: Science for Life with Physiology

Question

The risks faced by small populations include ________. A. erosion of genetic variability through genetic drift; B. decreased fitness of individuals as a result of inbreeding; C. increased risk of experiencing natural disasters; D. A and B are correct; E. A, B, and C are correct

Step-by-Step Solution

Answer

Option D: A and B are correct.

Step 1: Understanding the Question

The question is asking us to identify risks that are unique to small populations. It provides five options to choose from, including various potential risks.

Step 2: Analyzing Option A

Option A states that small populations are at risk of genetic variability erosion due to genetic drift. This is true because genetic drift has a more significant impact when there are fewer individuals to contribute genetic information.

Step 3: Analyzing Option B

Option B suggests that small populations face decreased fitness due to inbreeding. This is a valid concern because inbreeding is more likely in small populations, which can lead to the expression of deleterious alleles and reduced overall fitness.

Step 4: Analyzing Option C

Option C mentions increased risk of natural disasters. While natural disasters can affect any population, small populations might be more vulnerable in the aftermath due to fewer resources and reduced ability to recover, but this is not typically listed as a unique risk associated specifically with small populations.

Step 5: Evaluating Combined Options

Option D includes both A and B, which are correct risks for small populations as previously analyzed. Option E includes A, B, and C; however, while natural disasters are a risk, it is not considered an inherent risk due to population size alone.

Step 6: Choosing the Correct Answer

Based on our analysis, Option D, which lists A and B as the correct risks, is the most accurate choice. These are the commonly discussed risks specific to small populations.

Key Concepts

Inbreeding

Inbreeding occurs when individuals in a population are more likely to mate with relatives than with non-relatives. This is more common in small populations. When individuals breed with close relatives, it can increase the chance that harmful genetic traits are passed down. This is due to both parents possibly carrying recessive alleles that only manifest when two copies are present. Inbreeding can lead to:

• Expression of deleterious alleles: Recessive harmful traits can appear more frequently.
• Reduction in genetic diversity: A smaller gene pool results in less variation.
• Decrease in individual fitness: Lower survival and reproduction rates due to poor traits.

These effects can make a population less adaptable to environmental changes, increasing their risk of extinction. Managing inbreeding is crucial in conservation biology to maintain healthy populations.

Small Populations

Small populations are especially vulnerable to several genetic risks, primarily because they have fewer individuals contributing to the gene pool. This means that every individual's genetic makeup carries more weight in shaping future generations. One major genetic concern for small populations is genetic drift, which refers to random changes in allele frequencies. In a small population:

• Genetic drift can significantly alter allele frequencies rapidly, potentially leading to the loss of beneficial alleles.
• The effects of genetic drift are more pronounced since each individual's genetic contribution is larger.
• Such changes can occur faster than natural selection might counterbalance them, leading to unpredictable changes in the population's genetic structure.

This unpredictability is why conservation efforts often focus on increasing population sizes to preserve genetic diversity and stability.

Population Genetics

Population genetics is the study of genetic variation within populations and involves the examination of changes in allele frequencies under different evolutionary influences such as mutation, natural selection, genetic drift, and gene flow. Key aspects include:

• Genetic drift: It affects allele frequencies randomly and has a larger impact in smaller populations.
• Natural selection: This process often competes with genetic drift in shaping genetic variations.
• Inbreeding: Increases homozygosity and can lead to inbreeding depression.

Understanding population genetics helps scientists develop strategies to conserve endangered species, ensuring they maintain enough genetic diversity to adapt and survive environmental pressures. It's a crucial tool for managing small and inbred populations, aiming to minimize the risks of diminished fitness and potential extinction.