Problem 6 - Campbell Biology

Question

Which of the following is not required for a behavioral trait to evolve by natural selection? (A) In each individual, the form of the behavior is determined entirely by genes. (B) The behavior varies among individuals. (C) An individual's reproductive success depends in part on how the behavior is performed. (D) Some component of the behavior is genetically inherited.

Step-by-Step Solution

Answer

Option A is not required.

Step 1 - Understand Natural Selection

Natural selection is a process where organisms better adapted to their environment tend to survive and produce more offspring. Key criteria for a trait to evolve by natural selection include variation, inheritance, and differential reproductive success.

Step 2 - Evaluate Option A

Option A states the behavior is entirely determined by genes. For a trait to evolve by natural selection, it's not necessary for the behavior to be entirely determined by genes; partial genetic determination is sufficient. Hence, this option is suspect.

Step 3 - Evaluate Option B

Option B states the behavior varies among individuals. Variation in behavior is a crucial component for natural selection. Thus, this option is required for the process.

Step 4 - Evaluate Option C

Option C states reproductive success depends on the behavior. Differential reproductive success based on behavior is another key factor in natural selection. Thus, this option is also required.

Step 5 - Evaluate Option D

Option D states the behavior is genetically inherited. For a trait to be subject to natural selection, there must be some genetic basis. Therefore, inheritance of the behavior is necessary.

Step 6 - Conclude

Based on the evaluations, Option A is not required for a behavioral trait to evolve by natural selection.

Key Concepts

natural selection

Natural selection is a core mechanism of evolution, first described by Charles Darwin. It explains how traits that are beneficial for survival and reproduction become more common in a population over time. For behavioral traits to evolve through natural selection, there must be variation among individuals. This means that different individuals exhibit different behaviors. Additionally, the behavior must be partly inheritable, meaning some component of it is passed from parent to offspring through genes. Finally, individuals with certain behaviors must have a higher chance of surviving and reproducing, leading to differential reproductive success. This process ensures that advantageous behaviors become more frequent in future generations.

genetic variance

Genetic variance is essential for natural selection to act upon a population. It refers to the diversity of genetic traits within a population. This diversity can result in a range of behaviors among individuals. Genetic variance arises through mutations, genetic recombination during sexual reproduction, and other genetic mechanisms. Without this variance, all individuals would behave similarly, and there would be no raw material for natural selection to work on. Variation in genes contributes to differences in behaviors, and these differences can be selected for or against, depending on their impact on survival and reproduction.

reproductive success

Reproductive success is a measure of how many offspring an individual produces and how many of those offspring survive to reproduce themselves. In the context of natural selection, behaviors that increase an individual's reproductive success become more common over time. Successful behaviors might include finding food more efficiently, avoiding predators, or attracting mates. These behaviors contribute to an individual's fitness, which is their ability to survive and reproduce. Differential reproductive success based on behavior means that some behaviors lead to more descendants than others, driving the evolution of those behaviors in the population.

behavioral genetics

Behavioral genetics examines the role of genetic factors in shaping behaviors. It seeks to understand how much variation in behavior is due to genetic differences and how genes interact with the environment to influence behavior. Researchers study twins, family members, and animal models to uncover the genetic basis of behaviors. For a behavioral trait to evolve by natural selection, some portion of the behavior must be genetically inherited. This genetic component ensures that advantageous behaviors can be passed down to future generations, allowing those behaviors to spread through the population over time.