1. Ch. 17 The evolution of populations
Objectives
Identify the main sources of genetic variation in a population
Determine allele frequencies given population data
Describe the different mechanisms of speciation (a new species arising)
Ch. 17 The evolution of populations

2. Populations and Gene Pools
All the genes of a population, including the different alleles for each gene
Q: What is allele frequency and how do I calculate it?
The number of times an allele appears in a population divided by the total number of alleles for that gene.

3. Lets Practice!

4. Allele Frequency Calculation
Genotypes:
BB – Dark Brown
Bb – tan
bb – light
What is the allele frequency for b?
Out of 40 total alleles for color (2 alleles/bug)
22/40 = .55 or 55%

5. 17.1 – 17.2 Genes and Population Change
FQ’s:
How do we get diversity in a species?
What are the types of natural selection?
What causes reproductive isolation
In evolution, what does a “cause and effect” relationship look like?

6. Sources of Genetic Variation
Mutations
Sexual Reproduction (combinations of alleles)
Lateral Gene Transfer (bacterial conjunction)

7. Natural Selection on Polygenic Traits

8. Isolating Mechanisms that cause Reproductive Isolation
Behavioral – Songs or rituals
Geographical
Temporal – time of day or seasons

9. Survival of the weak and scrawny
5 min. SSR
Working on questions with your group
Group discussion
Survival of the weak and scrawny

10. 17.3 – The Process of a New Species Arising = Speciation
FQ: How do new species arise?
ET: Considering your butterfly graph, do you think our butterflies will evolve into separate species?