Evolutionary Biology Test 1

A population of bacteria is exposed to a high dose of antibiotics. Initially, most of the bacteria are susceptible to the drug, but a few individuals possess a mutation that allows them to survive. After several days of treatment, the entire remaining population consists of antibiotic-resistant bacteria. Which statement best describes the selection pressure at work?

• Selection favored the average individuals who could hide from the drug.

• The selection pressure favored the extreme phenotype of high resistance, shifting the population mean.

• Disruptive selection occurred, creating two distinct populations of bacteria.

• No selection occurred; the bacteria simply learned how to fight the medicine

In a forest habitat, a sudden increase in pollution causes the bark of trees to turn much darker. A population of moths living on these trees ranges in color from very light to very dark. Over several generations, the average color of the moth population becomes significantly darker. This is a classic example of directional selection because:

• The intermediate (medium-colored) moths are now the most fit.

• Both extreme phenotypes (very light and very dark) are favored equally

• One extreme phenotype is favored, shifting the population's trait distribution.

• The total genetic variation in the population has increased.

In a small island population of lizards, a few individuals with a unique coloration are isolated after a storm. Over time, this isolated group develops distinct traits that differ from the mainland population. What is the primary mechanism driving these changes in the isolated lizard population?

• Genetic drift due to the founder effect.

• Mutation introducing new traits into the population.

• Natural selection favoring the most common traits.

• Gene flow from the mainland population.

A group of colonists settles on a remote island, bringing only a small number of individuals from their original population. As generations pass, the island population exhibits traits that are significantly different from the original population. This phenomenon is best explained by which of the following?

• Hybridization with local species.

• Stabilizing selection maintaining the original traits.

• Adaptive radiation due to environmental pressures.

• Genetic drift resulting from a small founding population.

After a volcanic eruption, a small group of birds survives on a new island. This group has a limited genetic diversity compared to the original population. What is a likely consequence of this limited genetic diversity over time?

• Higher risk of extinction due to inbreeding depression.

• Enhanced survival due to a more uniform trait distribution.

• Greater potential for rapid evolution.

• Increased adaptability to changing environments.

Which of the following scenarios best illustrates convergent evolution?

• A population of fish evolves into two distinct species due to geographical isolation.

• Different species of birds develop similar beak shapes to exploit similar food sources.

• Two species of mammals develop different adaptations to their unique environments.

• A group of reptiles evolves into various forms due to adaptive radiation.

In a study of two closely related species of plants, one species develops a drought-resistant trait while the other develops a trait for increased water retention. This is an example of:

• Parallel evolution since both species are evolving similar traits.

• Stabilizing selection maintaining their original traits.

• Divergent evolution as they adapt to different ecological niches.

• Convergent evolution due to similar environmental pressures.

Two species of marsupials in Australia and South America have developed similar body shapes and ecological roles despite being geographically separated. This phenomenon is best described as:

• Parallel evolution as they adapt to similar habitats.

• Divergent evolution due to common ancestry.

• Convergent evolution resulting from similar environmental challenges.

• Adaptive radiation leading to diverse forms.

A small population of a rare bird species is established on a remote island after a storm. This population exhibits unique feather patterns that differ from the mainland population. What is the primary evolutionary mechanism responsible for these differences?

• Mutation introducing new traits into the population.

• Natural selection favoring specific traits.

• Genetic drift due to the founder effect.

• Gene flow from the mainland population.

In a study of a newly formed population of fish in a lake, researchers observe that the genetic diversity is significantly lower than that of the original population. What is a likely consequence of this reduced genetic diversity?

• Increased adaptability to environmental changes.

• Enhanced survival due to uniform traits.

• Higher risk of extinction due to inbreeding depression.

• Greater potential for rapid evolution.