Ohio Assessment for Educators (OAE) Integrated Science (024) Practice Exam

What does stabilizing selection favor?

1. Extreme phenotypes

2. Intermediate variants

3. Population isolation

4. Non-adaptive traits

The correct answer is: Intermediate variants

Stabilizing selection is a type of natural selection that favors intermediate phenotypes over extreme ones. This process reduces variation in a population and promotes the characteristics that are most suited to a stable environment. In stabilizing selection, individuals with traits that are too extreme may find it more difficult to survive and reproduce, while those with average traits are more likely to thrive and pass on their genes. For example, in a population of birds, if very large or very small beaks are less efficient for feeding on available food sources, birds with beaks of intermediate size would have a better chance of survival. This preference for the average phenotype helps maintain the status quo within the population, keeping the species well-adapted to its environment. In contrast, options that suggest extremes, population isolation, or non-adaptive traits do not align with the concept of stabilizing selection, which emphasizes the advantages of traits that are neither at the extremes nor maladaptive.