Speciation
Reduced gene flow between population leads to genetic divergence from mutation, natural selection, and drift.
The genetic divergence may eventually lead to speciation.
Usually, speciation creates two or more distinct species from one ancestral group.
Defined by reproductive isolation, independent branches on phylogenetic tree.
Speciation creates evolutionarily independent populations
Defining a Species
- Biological: Reproductively isolated; do not interbreed or fail to produce fertile offspring
- Morphological: structural features (size, shape, etc.)
- Phylogenetic: reconstruction of evolutionary history (descent from common ancestor)
Reproductive Isolation
- Reduced gene flow, selection, drift can lead to formation of new species.
- Speciation results in formation of reproductive isolating mechanisms:
- Prezygotic isolating mechanisms
- Prevent mating from taking place.
- Postzygotic isolating mechanisms
- Create reproductive isolation even when members of two population mate with each other.
Average time for Speciation
Average time is like 100k to 10 mil years.