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Difficulty: HardModern Evolutionary Theory and Genetic Basis of Evolution

Match each microevolutionary mechanism of modern evolutionary theory on the left with its precise effect on population genetics on the right.

  • Genetic drift in small isolated populationsCauses stochastic, non-adaptive fluctuations in allele frequencies that may lead to the random loss or fixation of alleles.
  • Natural selection acting on phenotypic variationSystematically increases the frequency of alleles that confer higher relative fitness in a specific environment.
  • Gene flow between distinct populationsIncreases genetic diversity within a recipient population while reducing genetic divergence between separated populations.
  • Germline DNA sequence mutationServes as the ultimate source of brand-new alleles, introducing novel genetic variation into the gene pool.

Answer

Genetic drift in small isolated populations matches stochastic non-adaptive fluctuations in allele frequencies; Natural selection acting on phenotypic variation matches systematically increasing the frequency of alleles conferring higher relative fitness; Gene flow between distinct populations matches increasing internal genetic diversity while reducing divergence between populations; Germline DNA sequence mutation matches serving as the ultimate source of brand-new alleles.
In Neo-Darwinian synthesis, microevolutionary changes are driven by distinct genetic mechanisms: germline mutations supply raw genetic material by producing new alleles; genetic drift alters allele frequencies by chance in small populations; natural selection systematically promotes alleles conferring relative fitness; and gene flow exchanges genetic alleles across population boundaries.

Step-by-Step Solution

1
Analyze the impact of small population size on allele sampling.
Identify that small sample sizes produce random, non-adaptive sampling errors.
Genetic drift alters gene pools purely through chance events rather than survival advantage.
2
Evaluate how differential reproductive success affects gene frequencies.
Connect natural selection to directional, adaptive shifts in allele frequencies.
Organisms bearing beneficial phenotypic traits leave more offspring, systematically propagating their alleles.
3
Determine the population genetic consequences of allele movement between populations.
Match gene flow to homogenization between populations and increased variation within the receiving population.
Immigration introduces novel alleles into the recipient gene pool while reducing genetic distance between source and sink groups.
4
Identify the primary origin of completely new genetic alleles.
Match germline mutation to the creation of novel genetic material.
Recombination reshuffles existing alleles, whereas mutation is the sole mechanism capable of generating new molecular alleles.

Key Concept

Microevolutionary Mechanisms and Population Genetics
Estimated Time:2m 0s
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Topics

Modern Evolutionary Theory and Genetic Basis of Evolution

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