Biology Mechanisms of Natural Selection Flashcards

Convergent evolution is best demonstrated by which example?

Answer: The wings of bats and birds

Bat and bird wings evolved flight independently in separate lineages, representing convergent evolution of analogous structures.

Which statement about mutations and natural selection is most accurate?

Answer: Mutations are random; selection acts on the variation they create

Mutations arise randomly and independently of need; natural selection then acts on the phenotypic variation they generate.

If a population of rabbits shows p = 0.7 (frequency of allele A) and q = 0.3 (frequency of allele a), what is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium?

Answer: 0.42

Heterozygote frequency = 2pq = 2(0.7)(0.3) = 0.42 under Hardy-Weinberg equilibrium.

An organism that produces many offspring but provides no parental care is exhibiting which life history strategy?

Answer: r-selection

r-selected species maximize reproduction by producing many offspring with little investment in each individual offspring.

Kin selection explains altruistic behavior because:

Answer: Helping relatives can increase the spread of shared genes (inclusive fitness)

Kin selection favors altruism when the benefit to relatives (weighted by relatedness) exceeds the cost to the altruist, increasing inclusive fitness.

What is the primary reason that sexual reproduction accelerates evolution compared to asexual reproduction?

Answer: It generates new combinations of alleles through recombination and meiosis

Meiosis and recombination in sexual reproduction shuffle alleles into new combinations, greatly increasing the genetic variation on which selection can act.

Which mechanism of speciation occurs when a geographic barrier divides a population?

Answer: Allopatric speciation

Allopatric speciation occurs when a physical barrier (e.g., mountain range, ocean) geographically isolates populations, preventing gene flow.