1. Charles Darwin Wrote in 1859“On the Origin of Species by Means of Natural Selection”Wrote in 1859:“On the Origin of Species by Means of Natural Selection” Two main points: 1.Species were not created in their present form, but evolved from ancestral species. (Descent With Modification) 2.Proposed a mechanism for evolution:NATURAL SELECTION 2.Proposed a mechanism for evolution: NATURAL SELECTION

2. Speciation evolutionThe evolution of new species.

3. Species populations individuals interbreed fertileA group of populations whose individuals have the potential to interbreed and produce fertile offspring in a natural environment. (Ernst Mayr)

4. The biological species concept is based on interfertility rather than physical similarity

5. Ethnic Groups

6. Macroevolution vs. Microevolution?

7. Macroevolution is above the species level. Microevolution is at the species level.

8. Geographic Isolation ancestral separated geographical barrier.Induced when the ancestral population becomes separated by a geographical barrier. Example:Example: Grand Canyon ground squirrels

9. Geographic Isolation Kaibab Squirrel (left) Abert Squirrel (right )

10. Harris’ Antelope Squirrel (left) /White- tailed Squirrel (right)

11. Premating Isolating Mechanism: Geographical Isolation  The Grand Canyon is a geographical barrier that can promote speciation.  The Kaibab squirrel (left) lives on the North Rim while the Abert squirrel (right) lives on the South Rim.

12. Has speciation occurred during geographic isolation?

13. Reproductive Barriers mechanismimpedes fertile and/or hybrid offspringAny mechanism that impedes two species from producing fertile and/or hybrid offspring.

14. Reproductive Isolating Mechanisms Geographic Isolation

15. Reproductive Isolation reproductively isolated sub-populationResult of a radical change in the genome that produces a reproductively isolated sub-population within the parent population (rare). Example: Wood Frogs and Pickerel Frogs live in the same communities but mate weeks apart and have different mating callsExample: Wood Frogs and Pickerel Frogs live in the same communities but mate weeks apart and have different mating calls

17. Temporal Isolation (a specific type of reproductive isolation) Bishop’s Pine releases pollen in summer Monterey Pine releases pollen in early spring

18. Reproductive Isolating Mechanisms Sciurus niger, the fox squirrel breeds in May and June Sciurus carolinensis, the gray squirrel, breeds in July and August

19. Behavioral Isolation Ornate butterflyfish Bluestripe butterflyfish Reproductive Isolating Mechanism

20. Figure 24.3 Courtship ritual as a behavioral barrier between species Blue-Footed Boobies in the Galapagos Islands

21. Ecological Isolation White-throated Sparrow feeds in dense thickets White-crowned Sparrow inhabits fields and meadows

22. Adaptive Radiation Emergence of numerous species common ancestorEmergence of numerous species from a common ancestor introduced to new and diverse environments. Occurs as a result of Divergent Evolution Example:Example: Darwin’s Finches

23. Ensatina eschscholtzii, a ring species, here in the Golden State

24. A model for adaptive radiation on island chains

26. Different geographic regions, different mammalian “brands” – Eutherian vs. MarsupialsConvergentEvolution

27. Interpretations of Speciation Two theories:Two theories: 1.Gradualist Model: Slow changes in species overtime. 2.Punctuated Equilibrium: Evolution occurs in spurts of relatively rapid change. (Eldredge and Gould)

28. Gradualism Punctuated Equilibrium

29. Homeotic Genes – any of the master regulatory genes that control overall body plan of animals and plants by controlling the developmental fate of groups of cells The products of one class of homeotic genes called Hox genes provide positional information in an animal embryo.

30. “Evo-Devo” biologists compare developmental processes of different multicellular organisms “The amazing diversity of organisms has been produced by a modest number of genes” (Sean Carroll – University of Wisconsin) (Go Badgers!)

31. Hox mutations and the origin of vertebrates