Genetic information & variation

Speciation requires reproductive isolation that prevents gene flow between diverging groups, allowing independent genetic changes to accumulate and eventually produce distinct species. Choice A is incorrect because migration alone does not create isolation; without barriers, interbreeding continues and divergence cannot be maintained.

The Hardy–Weinberg principle holds only when a population experiences no selection, no mutation, no migration, random mating, and is infinitely large, so allele frequencies remain constant. Answer A is wrong because migration introduces new alleles, violating the no‑migration assumption, and the model explicitly excludes gene flow.

A silent mutation changes a DNA base pair but, due to the degenerate nature of the genetic code, the altered codon still codes for the same amino acid. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.

• !Answer A is wrong because migration introduces new alleles, violating the no‑migration assumption, and the model explicitly excludes gene flow.
• !Choice A is incorrect because migration alone does not create isolation; without barriers, interbreeding continues and divergence cannot be maintained.

Answer each from memory — you'll see instantly whether you're right and why.

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