1. Macroevolution
Macroevolution is the study of major biological changes evident in the fossil record
Includes the following:
Multiplication of species
Origin of structures like feathers and large brains
Diversification of species – like flowers
Mass extinctions that lead to explosions - like the explosion of mammals after the dinosaurs became extinct

2. speciation Speciation is the origin of new species
Branching vs. non-branching
Branching – a lineage is split into two or more species
Non-branching – initial species becomes new species

3. Anagenesis vs. Cladogenesis

4. The Origin of Species
Biological species concept – groups of interbreeding natural populations whose members ONLY breed with each other to create fertile offspring.
What keeps members of different species apart?

5. Reproductive Barriers
Prezygotic barriers – occur before conception
Post-zygotic barriers – occurs after conception

6. Pre-zygotic Barriers
Temporal Isolation – mating or flowering occur at different time of the year/day
Ex. Western spotted skunks breed in fall, while eastern spotted skunks breed in the late winter
Habitat Isolation – species living in the same region may occupy different habitats
Ex. Some Garter snakes live in water/some on land
Behavioral Isolation-courtship rituals are very specific
Ex. Birds
Mechanical isolation-structural differences in genitalia or flowers prevent copulation or pollen transfer
Ex. Insects and flowers
Gametic isolation- male sperm cannot fertilize the egg

7. Post-zygotic Barriers
Hybrid Inviability – hybrid zygotes fail to develop or reach sexual maturity
Hybrid Sterility – Hybrid individuals fail to produce young

8. Speciation
When a population is somehow severed from the parent population and over time its gene pool is altered.
Allopatric and sympatric

9. Allopatric speciation
Isolation is the result of a geographic barrier
Ex. Galapagos finches
True speciation only occurs if the remaining populations will NOT breed

10. allopatric

11. Sympatric
When a sub-population arises in the midst of the parent population
Many plant species have accidental polyploidy in meiosis. They produce zygotes with multiple sets of chromosomes.
They can no longer reproduce with parental generation.

12. Evolution of Wheat

13. What is the tempo of speciation?
Gradual vs. punctuated
Punctuated equilibrium model – species most often diverge in spurts of rapid change instead of slow and gradually.
Over a few to ten thousand years, genetic drift and natural selection can change small, isolated species

14. Punctuated Equilibrium

15. Archaeopteryx

16. Exaptation
Term used to describe a structure that evolves in one context, but becomes adapted for another. However, natural selection cannot anticipate future need
Ex. Light bones in reptiles

17. Evo-Devo How do evolution and development interface?
Genes control the development of an organism from zygote to adult
Turning these genes on and off at certain times can have a profound effect on development.
Paedomorphosis – the retention of juvenile features as an adult
Ex. axototl

18. Axototl

19. Chimpanzee vs. human skulls
We retain a skull more like that of our fetal skull

20. History of biological diversity
Macroevolution is tied to the history of the Earth
Fossils are recovered from various sources

21. Sedimentary rocks

22. Skulls

23. Petrified trees

24. Tracks

25. Body parts

26. Amber

28. Geological Time Scale
Four eras – Precambrian, Paleozoic, Mesozoic, Cenozoic
Fossils are dated by carbon dating
Handout
At the end of the paleozoic era (250mya), Pangaea was formed.
The formation of pangaea reduced coastline and changed the environment for many terrestrial species.
Changing ocean currents killed many marine species

29. Breaking of Pangaea 180 MYA during the mesozoic
Caused major geographic isolation

30. Continental drift

31. Patterns of Evolution
Divergent evolution – when two isolated population evolve independently (Ex. Brown and polar bears)
Adaptive radiation – rapid evolution of a variety of species from a single ancestor (ex. Darwin’s finches)
Convergent Evolution – when two organisms without a common ancestor occupy the same niche, so they have the same characteristics. (ex. Porpoise and penguin)

32. Patterns cont.
Parallel Evolution – two related species who have made similar evolutionary changes. Ex. Placental and marsupial wolf
Co-evolution – predator/prey relationships

33. Adaptive Radiation