Problem 1 - Campbell Biology

Question

Knowledge/Comprehension One characteristic that distinguishes a population in an extinction vortex from most other populations is that (A) it is a rare, top-level predator. (B) its effective population size is lower than its total population size. (C) its genetic diversity is very low. (D) it is not well adapted to edge conditions.

Step-by-Step Solution

Answer

C. its genetic diversity is very low.

Step 1: Understand the Concept of an Extinction Vortex

An extinction vortex refers to a situation where a population's decline becomes self-perpetuating, leading to eventual extinction. Genetic factors, demographic factors, and environmental factors often interact in this process.

Step 2: Identify Key Characteristics of Populations in Extinction Vortex

Populations in an extinction vortex generally suffer from problems such as reduced genetic diversity, inbreeding depression, population size reduction, and loss of fitness.

Step 3: Analyze Each Option

Option A: Being a rare, top-level predator does not necessarily mean the population is in an extinction vortex. Option B: A lower effective population size compared to the total population size is common in small populations but not exclusive to extinction vortex scenarios. Option C: Low genetic diversity is a critical factor in extinction vortices as it reduces the population's ability to adapt and survive. Option D: Not being well adapted to edge conditions can be a problem but is not a defining characteristic of an extinction vortex.

Step 4: Choose the Correct Answer

Based on the analysis, the characteristic that most distinctly identifies a population in an extinction vortex is its very low genetic diversity.

Key Concepts

Population Genetics

Population genetics is the study of the distribution and change in frequency of alleles within populations. This field examines processes such as mutation, natural selection, and genetic drift. These processes are essential in understanding how populations evolve over time.
When a population becomes small, genetic drift can lead to the loss of genetic variation. This makes it difficult for populations to adapt to new environmental changes, which is a critical aspect in the concept of the extinction vortex.
Additionally, genetic bottlenecks can occur, where a significant reduction in population size limits the gene pool. Hence, populations in an extinction vortex often suffer from genetic issues that exacerbate their decline.

Genetic Diversity

Genetic diversity refers to the total number of genetic characteristics in the genetic makeup of a species. It plays a crucial role in the survival and adaptability of organisms.
When genetic diversity is high, populations are better equipped to adapt to changing environments. This adaptability helps in overcoming diseases, environmental changes, and other survival challenges.
In an extinction vortex, one of the main issues is the severe reduction in genetic diversity. This reduced diversity diminishes the population's resilience to environmental stresses, making them more susceptible to extinction.

• Low genetic diversity
• Reduced adaptability
• Higher susceptibility

Inbreeding Depression

Inbreeding depression occurs when a population becomes so small that individuals begin to mate with close relatives. This leads to an increase in the expression of deleterious recessive genes.
The consequences of inbreeding depression are severe as it can lead to reduced fitness, lower reproduction rates, and higher mortality rates. These factors accelerate the population's decline, making recovery even more difficult.
In the context of the extinction vortex, inbreeding depression is one of the biological challenges that ensnare the population further into the vortex.

• Increased genetic disorders
• Reduced survival rates
• High mortality

Population Ecology

Population ecology examines how populations interact with their environment and how these interactions influence population dynamics. Factors such as resource availability, predation pressure, and disease prevalence are key aspects.
In an extinction vortex, environmental and demographic factors compound the genetic challenges. For example, reduced population size can lead to insufficient mating opportunities and skewed sex ratios.
Understanding population ecology helps in identifying the external pressures a population faces. It highlights how habitat loss, environmental changes, and human impacts can contribute to the population's decline.

• Environmental interactions
• Resource limitations
• Human impacts