Part I: Populations & Natural Selection (Molles 4th-C8/5th-C4)
1. What is a population?
- ecology: group of individuals of the same species inhabiting the same area
- genetics: group of interbreeding individuals of the same species isolated from other groups
2. Process of Natural Selection
- Inheritance: by Mendel
- Evolution: change in gene frequency within a population over time.
- Small-scale evolution: changes in gene frequency in a population from one generation to the next.
- Large-scale evolution: the descent of different species from a common ancestor over many generations.
- What is Natural Selection?
- Key mechanishm of evolution.
- The process by which heritable traits that are likely to improve an organism’s chances of survival and successfully reproduce become more common in a population over successive generations.
- VIST
- Variation : genetic variation upon which selection works
- Inheritance : genetic traits inherited
- Selection : favourable traits survive and passed on
- Time : evolution happens over generations (small-scale), speciation takes much longer (large-scale).
- Use it or Lose it: traits that are not actively maintained by natural selection rapidly disappear.
- Relaxed selection: environmental changes eliminates selection pressure that maintain a trait -> degeneration due to the loss of selection against mutations.
- Selected loss: driven by natural selection
3. Population genetics and Natural Selection
a. Variation within populations
- phenotypic variation among individuals in a population, effects of genes and environments.
- Potentilla glandulosa
- In the same species where there are no genetic difference between populations, all plants would grouw well. (Null Hypothesis)
- In fact, the plants did not grow equally well
- Changes in genotype -> optimalization
- Ecotype:
- each ecotype performed best under conditions most closely resembling its natural habitat
- genetically distinctive and is best adapeted to an optimal habitat.
b. The Hardy-Weinberg equilibrium
c. Natural Selection
d. Evolution by natural selection
e. Random processes
Part II: Population Distrbution and Abundance (Molles 4th/5th C9)
