Two populations of a freshwater fish have lived in separate lakes for many generations. The populations have similar body shapes. When eggs from one population are fertilised by sperm from the other population, the offspring survive but are infertile.
Which conclusion about these fish is supported by the evidence?
The populations look similar, so they have not diverged and are still the same species.
The infertile offspring show variation within one species, so speciation has not yet occurred.
The populations can still produce offspring together, so they are still the same species.
The offspring are infertile, so the populations are separate species even though they look similar.
71 exam-style questions on AQA GCSE Biology 6.3 The development of understanding of genetics and evolution, covering 6.3.1 Theory of evolution, 6.3.2 Speciation, 6.3.3 The understanding of genetics, 6.3.4 Evidence for evolution, 6.3.5 Fossils, 6.3.6 Extinction, and 6.3.7 Resistant bacteria. Each one has a worked solution and a mark scheme showing where the marks go.