1. Population Genetics and Speciation
Chapter 16:
Population Genetics and Speciation

2. Chapter 16.1
Genetic Equilibrium

3. Evolution by Natural Selection
widely accepted by end 1800s
Further genetics research supported it

4. What’s population genetics?
Studying evolution of genes in a population
Type of Microevolution
What’s an allele?
What’s a species?
Same genotypes?
Interbreed?

5. Can an individual evolve?
NO!!!!!

6. What are causes of VARIATION?
Environmental factors
Heredity
Mutations
Recombination
Random pairing of gametes
Complex characters

8. GENE POOL... ALL ALLELES IN POPULATION Allele Frequency Example:
20 lions in population
½ are heterozygous
¼ are hom dom
¼ are hom rec
Freq of A?
Freq of a?

9. How’s allele frequency different from phenotype frequency?

11. Hardy-Weinberg Equilibrium
Genotype frequencies usually stay ~same across generations UNLESS acted on by outside influences...
?????
Important b/c...
Tells us what forces may disrupt genetic equilibrium & allow for evolution to take place

12. How it can change the population:

13. 5 Assumptions of Hardy-Weinberg Principle:
No net mutations; alleles remain same.
No immigration or emigration
Large population size
Random mating
No selection occurring

15. 5 Factors that can lead to Evolution:
Genetic drift
Gene flow
Mutation
Sexual selection
Natural selection

16. REVIEW... What are 3 causes of genetic variation in a population?
What’s a GENE POOL?
How do you calculate genotype & phenotype frequency?
What are the assumptions of the H-W principle?
How does the pairing of gametes produce genotypic variation?

17. Allele Frequency Practice
Opener, Wednesday April 24th
Allele Frequency Practice
There are 100 Heffalumps in the population.
80 have an extra-long snout (homozygous dominant).
15 have a medium-sized snout (heterozygous).
5 have a short snout (homozygous recessive).
Calculate the allele frequency for both alleles.

18. Some tigers have a recessive allele that causes an absence of fur pigment in homozygous individuals (albino tigers).
Do you think the white phenotype in tigers is favored by natural selection?
Why or why not?
What does this mean for the occurrence of the allele in future generations (more, less)?

19. List the 5 assumptions of Hardy-Weinberg Equilibrium…
ANY EXCEPTIONS 
CHANGE IN ALLELE FREQ 
EVOLUTION OF POPULATION OVER GENERATIONS

20. 16-2: Disruption of Genetic Equilibrium Looking at those H-W assumptions…continuing on your chart.

21. 1. Mutations Mutagens increase mutation rates Radiation, chemicals
New alleles
- / 0 / + effects

22. 2. Gene Flow Change in population size...how? Immigration, emigration
Migration, seed dispersal
Male apes moving to new troops...gene flow?

23. 3. Genetic Drift Allele freq changes due to random event/chance
Small pop  bigger effects

24. 4. Nonrandom Mating SURVIVE & REPRODUCE!
Many species don’t mate randomly!
Geography, similar traits (assortative mating), sexual selection
SURVIVE & REPRODUCE!

25. 5. Natural Selection SURVIVE & REPRODUCE! 3 patterns/modes
Ongoing in nature
SURVIVE & REPRODUCE!
3 patterns/modes

27. Campbell CD
Activity 13D

28. REVIEW! How can mutation lead to evolution? What’s gene flow?
How’s it different from genetic drift?
Why does genetic drift affect small populations more dramatically?
Stabilizing selection? Example?
Disruptive?
Directional?
Example OTHER THAN A PEACOCK/BIRD for sexual selection?

29. Practice!
Beads
Rat Islands Or
Natural Selection/Camouflage

30. Opener, Thurs. Jan 7th
Use the following terms in a sentence to summarize what you learned yesterday & LINK it to last night’s homework:
Genetic equilibrium
Gene pool
Speciation

31. Opener, Thursday Jan. 7th
Some tigers have a recessive allele that causes an absence of fur pigment in homozygous individuals (albino tigers).
Do you think the white phenotype in tigers is favored by natural selection?
Why or why not?
Will it be selected “for” or “against”?
What does this mean for the occurrence of the allele in future generations (more, less)?

32. 16-3: Speciation

33. How many species are on Earth?
BioBucks! Estimate w/reference…

34. http://www. plosbiology. org/article/info%3Adoi%2F10. 1371%2Fjournal

35. Reproductive Isolation:
Can be caused by... 1. 2. 3.
Is the final stage of ...

36. 1. Behavioral Isolation Courtship/mating behavior
Prevents reproduction between populations
(Leads to evolution of new species)
Examples: bird songs, firefly lights

37. 2. Geographical Isolation
Physical barriers divide a population into 2 or more groups
Prevents repro. b/w pops.
(Leads to evolution of new species)
Examples: 10,000 yrs ago—Colorado N. & S. rim of Grand Canyon
Mountains—salamanders
Islands—finches, tortoises!

38. 3. Temporal Isolation TIMING of reproductive or courtship events
prevents repro. b/w pops.
(Leads to evolution of new species)
Examples: flowers w/ diff. bloom times
Clams—different spawning times

39. What’s speciation? Common ancestor Deviations
Similar  very different
How can some be similar and some so different?
Time!

40. How do scientists determine if 2 organisms are the same species?
Morphology, anatomy
Molecular evidence
INTERBREED & PRODUCE
FULLY FERTILE OFFSPRING

41. Isolation, leads to speciation
Reproductive, Temporal, or Geographic?
Example:
Physical barrier divides pop into 2 or more groups that can no longer reproduce with each other
Allopatric speciation--
Differences in courtship/mating behaviors prevent reproduction between pops.
Prezygotic:
Postzygotic:

43. How long does this take? Depends on the species & conditions!
Gradualism: Punctuated equilibrium:

45. Test Tomorrow… Review Ch 17 also! Ch 14, 15, 16
Let’s go over your quiz so you can STUDY it
Test Corrections available …
Friday, Monday, Tuesday only.
Must have HW completed!

48. Chapter 16 Activity: Data Analysis, Frequencies, & Natural Selection
Identifying patterns in data by studying graphs and charts is important in making future predictions and hypotheses.
Population Genetics
Swordtails are small freshwater fish. One section of the tail of the male fish is elongated and has a specific color pattern of two black lines running the outside length of the section, with yellow in the middle. Scientists conducted an experiment to determine which component of the color pattern may be most attractive to the female swordtail during mating. The females were exposed to three different stimuli: a normal male fish tail, an all-black male fish tail, and an all-yellow male f ish tale. The response of the females to each stimulus was recorded. The graph below shows the results of the research.
Groups of 3
Read
Analyze Graph
Answer questions AS A GROUP
Write on your own paper

51. Concept Map: http://my. hrw
Bill nye, jeff corwin

52. AQUATERRA ACTIVITY!

54. PAIR-SHARE

55. Sandstone, siltstone
Die, water, sink, more aquatic fossils
Erosion (mts, hills, river sediment, etc.)...Appalachian used to be bigger than Himalayan mts.
No plate pushing up App. Now, landmass far gone...