1. Origin of Species How do we define species?
A population of organisms that produces viable fertile offspring in nature.
When does this definition fall apart?
Asexual,extinct and blurred organisms
What definition is used in these cases?
Morphospecies concepts

2. What is the main distinction that must occur for the origin and integrity of distinct species?
Reproductive isolation

5. Which sort of reproductive isolation mechanism is at work in the following examples?
Firefly signals with specific flashes to attract mates
male dragonfly has appendages that clasps female during mating
brown trout breed in the fall and rainbow trout in the spring
1 type of garter snakes lives in the water and the other lives on land

6. Horse and donkey produce sterile mule
frogs that mate and produce offspring that do not quite develop

7. Biogeography of Speciation
What is the difference between allopatric and sympatric speciation?
Allopatric speciation involves a geographical barrier between 2 groups
Sympatric speciation is the result of a genetic isolation without a geographical barrier

8. Conditions for Allopatry
Peripheral isolate where the fringe organisms are already somewhat different from mainstream population
Genetic drift can occur to a small peripheral isolate
The genetic drift continues to change gene pool until the group is large
Natural selection will select the best fit traits among the new group to survive

10. Ring Species: Allopatric Speciation in Progress

11. Adaptive Radiation Islands are laboratories of speciation
Adaptive radiation is the evolution a number of different new species from a common ancestor
Archipelago's are the home of adaptive radiations

12. What sort of reproductive barrier is this?
Prezygotic
Has reproductive isolation occurred?

13. Sympatric Speciation
Genetic alterations result in a reproductive barrier
Can occur in a single generation
More frequently seen in plants
Nondisjunction and selfing leads to polyploidy
autopolyploid
alloployploid
Evolution of wheat

14. Sympatric Speciation in Animals
Under normal light
Under monochromatic light

15. Genetic Mechanisms of Speciation
Adaptive Divergence:
reproductive barriers evolve as secondary result of divergence
the barriers evolve to enhance reproduction within the group not to eliminate reproduction between groups
reproductive barriers occur as a side effect of the accumulated adaptive divergences

16. Tempo of Speciation
Gradualism
Punctuated Equilibrium

17. From Speciation to Macroevolution
Speciation is the boundary between micro and macroevolution
Cumulative change over vast amounts of time accounts for macroevoulution
How do evolutionary novelties evolve? …

18. Eye Evolution

19. Origin of Novelties How do large scale novelties arise?
Exaptation = modifications of older structures
Panda’s thumb stinger of bees etc…
Genetic changes that lead to devlopmental changes:
Allometric growth - relative rates of growth differs, change one stage and see big change
Alter timing of developmental events, such as sexually active juveniles
Alteration in homeotic genes
Evolution, however, is not goal oriented

30. Tetrapod evolution Fish; Hox gene leads to fin development
Chicken; same Hox gene leads to leg development