Chapter 10: Population & Evolutionary Genetics Flashcards
Evolution
Change in allele frequency of a population
Charles Darwin
Origin of Species (1859)
Take a population (5,000 fruit flies)
Average survival without food (20 hours)
Starve until 80% of flies
Dies
Feed survivors, allow them to
Breed
Starve offspring until
80% dies, takes longer than parent generation (average survival without food: 23 hours)
Repeat for many generations, selecting for
Starvation survival, generation 60: average survival: 160 hours
How does evolution occur? How do allele frequencies change in population?
- Mutation
- Genetic drift
- Migration
- Natural selection
Mutation
Change to genome
Mutation are randome events, although they can be
Encouraged (mutagens)
Mutations are the root of all
Genetic variation
Most mutation have negative effect by the two following:
1) Generally create non-functioning genes
2) If mutation creates functional gene, may or may not make the organism more fit
Genetic drift
Random changes in allele frequency
Unlike natural selection, the change does not impact
Fitness directly; it is just which allele combination are inherited from parents
Genetic drift can cause traits to
Increase or decrease in a population and acts more strongly on small population