1. Chapter 11 - Part 2
Chapter

2. Hardy Weinberg Equilibrium
Conditions for NO EVOLUTION of a population
1. Very large population
2. No emigration or immigration (gene flow)
3. No mutations
4. Random mating
5. No natural selection

3. 5 Factors that lead to Evolution
1. Small population
If it results in Genetic Drift
2. Gene flow
Immigration or emigration
3. Mutations
A new sequence of nucleotides
4. Sexual Selection – Nonrandom mating
5. Natural Selection

4. Section 11.5 Speciation via Isolation

5. Speciation?
Speciation - the rise of 2 or more species from an existing species
Species – capable of producing fertile offspring with other members of the species
Reproductive Isolation – when members of different populations can no longer produce fertile offspring successfully with other members of that population

6. So how do we get new species?
Populations can diverge through isolation
If the divergence is sufficient to prevent interbreeding between the two populations = new species
3 types of Isolation that can produce speciation
Behavioral
Temporal
Geographical

7. Fruit flies of the same species were genetically modified at the ds2 gene
There are 2 forms of the gene, and those who received the same form of the gene were attracted to each other, but were not attracted to those who received the other form of the gene
Males with 1 form of the gene could have mated with females with the other form, but never did.

8. Isolation that leads to speciation
1. Behavioral isolation
Isolation caused by differences in courtship or mating behaviors
2 species of crickets look identical, but have differently pitched songs that prevents interbreeding
Firefly species produce a different pattern of light flashing, so females of 1 species does not interbreed with males of another species

9. Isolation that leads to speciation
2. Geographic Isolation
Physical barriers that divide a population into 2 or more groups
Include rivers, mountains, dried-out lake beds, etc.

10.  Snapping shrimp and Isthmus of Panama
-- Pacific and Atlantic snapping shrimp could mate, but will not do so.

11. Isolation that leads to speciation
3. Temporal Isolation
Some timing component prevents reproduction between populations
Different pollination times of the year
Nocturnal (night activity) vs. diurnal (day activity)

12. Section 11.6 Patterns in Evolution

13. Convergent Evolution
Evolution toward similar structures in unrelated species
Wings on birds and wings on insects are analogous structures

14. Divergent Evolution
Evolution toward different traits in closely related species

15. Coevolution
The process by which 2 or more species evolve in response to changes in each other
2 species working together can coevolve
2 species in a predator-prey relationship can also coevolve

17. Extinctions Extinction – elimination of a species from Earth
Basically, a “fail” in terms of biology
It is hypothesized that 3 species go extinct every day
There are 2 types of extinctions
1. Background Extinctions
2. Mass Extinctions

18. 2 Types of Extinction Background Extinctions Mass Extinctions
Continuous level of extinctions
Low level
Equals that rate of speciation
Only affects a few other species in the local area
Mass Extinctions
Rare events (5 in last 600,000,000 years)
Global effects
Ice age or asteroid impacts

20. Speciation Occurs in Patterns
Punctuated Equilibrium
Long periods of stasis punctuated by bursts of mass speciations
So there is no change in species most of the time, then out of nowhere there is a brief period of significant change
Homo Evolutis
Adaptive Radiation
Rapid evolution of many diverse species from ancestral species.

21. ADAPTIVE RADIATION
ancestral species diversifies into many descendent species
descendent species usually adapted to wide range of environments