Answer: Random change in allele frequencies in a population due to chance events, especially significant in small populations.
- A The directed, seasonal migration pattern of animal populations moving regularly between distant seasonal habitats
- B Random change in allele frequencies in a population due to chance events, especially significant in small populations
- C Mutation that is deliberately directed by the organism itself toward a specific, predetermined adaptive outcome
- D Natural selection acting with roughly similar strength and predictability across populations of varying sizes
Correct answer: B. Random change in allele frequencies in a population due to chance events, especially significant in small populations
Explanation: Genetic drift: random, chance-based changes in allele frequencies, not due to selection. Most significant in small populations. Two special cases: Founder effect (small group colonizes new area) and Bottleneck effect (population reduced by disaster). Can lead to fixation or loss of alleles regardless of fitness.
A simple phylogenetic tree: a common ancestor branches into several descendant lineages over time, with each branch point marking a speciation event.
Concept context
Origin of life, Darwin's theory, natural selection, speciation, and evidence for evolution.