When a small group of individuals emigrates from a large parental population and colonizes a new geographical area, their distinct allele frequencies may establish a new species. This evolutionary phenomenon is termed the:
Answer and explanation
Correct answer: A. Founder effect
- Step 1: The founder effect occurs when a new colony is established by a very small sample of the original population.
- Step 2: Because the founding sample contains only a fraction of the original gene pool, rare alleles may become highly concentrated or completely lost purely by chance.
- Step 3: The descendant population becomes genetically distinct from the parent population (e.g., high incidence of Ellis-van Creveld syndrome in the Pennsylvania Amish).
Answer
Founder effect.
Why not the others: Bottleneck effect occurs when a catastrophic event dramatically reduces the size of an existing population; Hardy-Weinberg equilibrium describes constant allele frequencies without evolution; Heterosis is hybrid vigor resulting from outbreeding.
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