In a population of endangered kākāpō on Whenua Hou island, why does a severe genetic bottleneck increase extinction vulnerability?
Answer and explanation
Correct answer: A. A bottleneck reduces population size
- Step 1: Step 1: A genetic bottleneck occurs when a population collapses to very few individuals (kākāpō dropped to ~50 birds in the 1990s). Step 2. Step 2: Rare alleles are lost, leaving low genetic variation. Inbreeding reveals deleterious recessive alleles (infertility, deformities), and the uniform gene pool leaves the population defenseless if a new disease strikes. Answer: A bottleneck reduces population size. Why not the others: Bottlenecks destroy genetic variation; they never generate new alleles.
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