1. Speciation

2. Prezygotic isolation
Temporal – crickets mature at different times

3. Prezygotic isolation
Habitat – land vs. water garter snakes

4. Prezygotic isolation
Behavioral – firefly mating

5. Prezygotic isolation
Gametic – sea urchins shed gametes at same time
Common west coast species: Clockwise, upper Left: purple urchin Strongylocentrotus purpuratus red urchin S. franciscanus and green urchin S. droebachiensis

6. Prezygotic isolation
Mechanical

7. Postzygotic isolation
- hybrid viability
- hybrid sterility

8. Biological species challenges
Fossil species
- Bat from Wyoming
Asexual species
Butterfly lizard (Leiolepis ngovantrii)
Eschirichia coli
Ring species – Larus argentatus (herring gull)

9. 63 morphospecies of semaeostome jellyfishes
Fungi that rot a plant in Ecuador
Semaeostome jellyfish are large with frilly arms
Trilobites

10. Cryptic species

11. Phylogenetic species
Order Carnivora synapomorphy = Carnassial teeth
Suborder Feliformia synapomorphy = double chambered auditory bulb

12. Phylogenetic species

13. Allopatric speciation

14. Allopatric speciation - vicariance

15. Allopatric speciation - dispersal

16. Sympatric speciation
Potential explanation for speciation of cichlid fish in Lake Victoria

17. Hybridization