Speciation rates are highest when
- A
Population sizes are very large and gene flow homogenizes alleles across the entire range
- B
Environments are extremely stable and existing species fully saturate every available niche
- C
Mutation rates drop to zero and selection cannot act on any new heritable variation arising
- Dcheck_circle
Populations are isolated and face new ecological opportunities (e.g., new island, post-extinction niches)
Explanation
Isolation + new niches → rapid divergence. Adaptive radiations after mass extinctions illustrate this.