Explain how isolation changes gene pools, identify reproductive barriers and evaluate population evidence for speciation.
The confirmation of DNA as the genetic material, together with the elucidation of its structure by Crick and Watson, had a profound effect on modern biology.
Explain how isolation leads to speciation.
| a | speciation is a new species forming from an existing species/splitting of a species; |
| b | speciation depends on reproductive isolation/no interbreeding between populations; |
| c | gene pools of populations are separate/no gene flow between populations; |
| d | temporal isolation if two populations breed at different times/valid example; |
| e | behavioral isolation if breeding prevented by differences in behaviour/valid example; |
| f | geographical isolation if populations live in different areas / are separated by a physical barrier/valid example; |
| g | differences in mutations/genetic drift between isolated populations; |
| h | differences between environments cause different selection pressures/natural selection; |
| i | allele frequencies of isolated populations diverge; |
| j | evolutionary divergence/different evolutionary paths/different adaptation; |
| k | populations have become separate species when they are too different for successful interbreeding/for interbreeding to produce fertile offspring OR polyploidy can cause (instant) reproductive isolation; |