Evolutionary Mechanisms and Population Genetics

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A scientist is studying a population of butterflies and observes that the average wing length has remained constant over several generations. Which type of selection is most likely occurring?

Directional selection, favoring longer wings.
Stabilizing selection, favoring average wing lengths (correct)
Disruptive selection, favoring both short and long wings
Artificial selection, due to human interference

In a small, isolated island population of birds, the frequency of a particular allele changes significantly over a few generations due to random chance. Which evolutionary mechanism is primarily responsible for this change?

Mutation, introducing new alleles to the population
Gene flow, introducing alleles from other populations
Natural selection, as the allele must be beneficial
Genetic drift, due to the small population size (correct)

A new highway divides a population of frogs. Over time, the two resulting populations begin to exhibit different mating calls. This is an example of what?

Geographic isolation, due to physical separation (correct)
Temporal isolation, due to differences in mating seasons
Behavioral isolation, due to changes in mating rituals
Reproductive isolation, due to an inability to interbreed

Which of the following scenarios would violate the conditions for Hardy-Weinberg equilibrium?

A small population with non-random mating and natural selection (B) Signup and view all the answers

A population of plants is exposed to a new disease. Initially, a small number of individuals possess a gene that confers resistance to the disease. Over time, the frequency of the resistance gene increases significantly in the population. Which evolutionary mechanism is primarily responsible for this change?

Natural selection, favoring individuals with the resistance gene (C) Signup and view all the answers

A group of seeds from a mainland plant species are carried by the wind to a remote island, where they establish a new population. Over time, the island population diverges genetically from the mainland population. Which evolutionary mechanism likely played a significant role in this divergence?

Founder effect, due to the small initial size of the island population (D) Signup and view all the answers

Two species of orchids live in the same rainforest but flower at different times of the year, preventing them from interbreeding. What type of reproductive isolation is this?

Temporal isolation, due to differences in timing (A) Signup and view all the answers

Which of the following is an example of genetic drift?

A population bottleneck drastically reduces genetic diversity (D) Signup and view all the answers

If a scientist observes an allele frequency change in a population, what can be assumed?

The population is evolving (C) Signup and view all the answers

A drug has a half-life of 6 hours in the human body. If a patient takes 200mg of the drug, about how much will remain in their system after 12 hours?

50mg (D) Signup and view all the answers

How did Darwin's observations of Galapagos finches contribute to his theory of evolution by natural selection?

They revealed varied beak structures adapted to different food sources, suggesting descent from a common ancestor with modification. (D) Signup and view all the answers

Which of the following best illustrates the concept of artificial selection?

Breeders selecting cows with high milk production for breeding. (B) Signup and view all the answers

Which of the following is NOT a key principle of natural selection?

Favorable traits acquired during an organism's lifetime are passed to its offspring. (B) Signup and view all the answers

How does the concept of 'fitness,' as defined by Darwin, relate to natural selection?

Fitness is an organism's ability to survive and reproduce successfully in a specific environment. (A) Signup and view all the answers

What can biogeography tell us about the evolutionary history of species?

It explains how species distribute based on environmental factors, migration, and geological history. (C) Signup and view all the answers

Which of the following is the best example of a vestigial structure and what does it indicate?

The human appendix, indicating a structure that no longer serves its ancestral purpose. (D) Signup and view all the answers

How do homologous structures support the theory of evolution?

They indicate shared ancestry between different species, even if the structures have different functions. (D) Signup and view all the answers

What does the gene pool of a population represent, and why is it important in the context of evolution?

The total collection of genes and alleles in a population; important for providing the raw material for evolutionary change. (A) Signup and view all the answers

Which process directly results in a new allele in the gene pool?

Mutation (C) Signup and view all the answers

How does natural selection influence the composition of a gene pool over time?

It increases the frequency of alleles that enhance survival and reproduction in a specific environment. (A) Signup and view all the answers

Darwin

Naturalist who collected specimens during his Beagle voyage; proposed evolution.

Galapagos finches

Birds that provided evidence of evolution via their beak variations.