1. Isolation and Speciation
Macroevolution in action!

2. Formation of a new species… what is a “Species”?
Many definitions of species exist
Morphological – based on finding physical/structural similarities
Advantages: applies to both sexual/asexual organisms
Disadvantage: subjective
Ecological – based on the niche of an organism (its role in ecosystem)
Phylogenetic – based on an animal’s ancestry/genetic history
Compare physical characteristics/molecular similarities
Paleontological – focus on morphologically-discrete species known only from the fossil record

3. Biologic Species concept
Defined as:
Population/group of populations that can successfully interbreed, producing viable, fertile offspring
Speciation often requires major genetic changes
Hinges on reproductive isolation – something that keeps two groups that would normally interbreed from doing so

4. Allopatric vs. Sympatric Speciation
Allopatric - “away from one’s fatherland”
Physical barrier divides 1 population into two
Mountains, channels, islands, rivers, lava flows, etc.
Leads to a divergence of the gene pool through mutations, selection, etc.
If enough time passes, will likely be unable to mate if reintroduced

5. Sympatric Speciation
Species evolves while alongside its fellow organisms.
How?
Polyploidy
Habitat differentiation
Sexual selection
Reminder: zygote = fertilized egg

6. Reproductive Isolation
Leads to speciation…
…By preventing gene flow among populations
Prezygotic Isolation – prevents fertilization
Mechanical
Habitat
Behavioral
Mating songs
Temporal
Gametic
Polyploidy (plants)

7. Mechanical

8. Habitat

9. Behavioral

10. Temporal

11. Gametic

12. Post-Zygotic Isolation
Fertilization has occurred, but the hybrid isn’t viable, can’t reproduce
Reduced hybrid inviability – development/survival of hybrids is impaired
Reduced hybrid fertility – hybrids fail to produce functional gametes
Hybrid breakdown – offspring of hybrids are feeble/infertile

13. Some examples of hybrids that are infertile (sterile)
Cool stuff!
(Male partner listed first)

14. Camel + Llama =

15. Cama

16. Tiger + lion =

17. Tiglon!

18. Lion + tiger =

19. Liger

20. Zebra + horse =

21. Zebroid

22. Donkey + horse =

23. Mule

24. Horse + Donkey =

25. Hinney

26. False Killer Whale + Dolphin

27. Wolphin

28. Leopard + Lion =

29. Leopon

30. Grizzly + Polar Bear

31. Grolar/ Pizzly

32. Goat + Sheep =

33. Geep

34. Cattle + Bison=

35. Beefalo

36. Human + Chimpanzee =

37. Humanzee?