Major changes in the history of life – usually present in the fossil record.
1. Origin of new species,
2.Origin of evolutionary novelty,
3. Diversification after evolutionary breakthrough,
4. Diversification after mass extinctions,
A population or group of populations whose members have the potential to naturally interbreed and produce fertile offspring.
1. Observable/measurable physical traits.
2. Ecological niches/unique adaptations.
3. Unique genetic history (DNA).
Reproductive barrier that impedes mating between species or hinders fertilization of eggs if members of different species should attempt to mate.
a) Temporal Isolation (different breeding times).
b) Habitat Isolation (different locations).
c) Behavioral Isolation (differences in rituals).
d)Mechanical Isolation (mismatched genitalia).
e) Gametic Isolation (mismatched gametes).
Formation of a new species as a result of genetic change from the original population; no geographic barrier.
Structure that became adapted for one function, later becoming adapted for a different function in a different context.