Genes within population
- 1. Five Agents of Evolutionary Change Prepared by: John Rey D. Ravago BSED SCIENCE 1-A 20.3
- 2. Learning Outcome 1)Define the five processes that can cause evolutionary change.
- 3. • The five assumptions of the Hardy–Weinberg principle also indicate the five agents that can lead to evolutionary change in populations. They are mutation, gene flow, nonrandom mating, genetic drift in small populations, and the pressures of natural selection. Any one of these may bring about changes in allele or genotype proportions.
- 4. Five Agents that Can Lead to Evolutionary Change in Populations Mutation Changes Alleles. Mutations are the ultimate source of genetic variation. Because mutation rates are low, mutation usually is not responsible for deviations from Hardy-Weinberg equilibrium. The ultimate source of variation. Individual mutation occur so rarely that mutation alone usually does not change allele frequency much.
- 5. Five Agents that Can Lead to Evolutionary Change in Populations Gene flow occurs when alleles move between populations. Gene flow is the migration of new alleles into a population. It can introduce genetic variation and can homogenize allele frequencies between populations. A very potent agent of change. Individuals or gametes move from one population to another.
- 6. Five Agents that Can Lead to Evolutionary Change in Populations Nonrandom mating shifts genotype frequencies. Assortative mating, in which similar individuals tend to mate, increases homozygosity; disassortative mating increases the frequency of heterozygotes. Inbreeding is the most common form. It does not alter allele frequency but reduces the proportion of heterozygotes.
- 7. Five Agents that Can Lead to Evolutionary Change in Populations Genetic drift may alter allele frequencies in small populations. Genetic drift refers to random shifts in allele frequency. Its effects may be serve in small populations. Statistical accidents. The random fluctuation in allele frequencies increases as population size decreases.
- 8. Five Agents that Can Lead to Evolutionary Change in Populations Selection favors some genotypes over others. For evolution by natural selection to occur, genetic variation must result in differential reproductive success, and it must be inheritable. The only agent that produces adaptive evolutionary changes.
- 9. 5 Assumptions of a Hardy-Weinberg Population 1) No Selection 2) No Mutation 3) No Gene Flow-No migration between populations to change allele frequencies 4) Infinite Population is necessary because the larger the population size is, the harder to change the allele frequency 5) Random Mating which is pretty much what it says: Mating being based on nothing other than the pure chance, making it random