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Natural selection works on individual organisms (differential reproductive success)... | ...but it is the population that evolves. |
Population: | Any group of individuals, usually of a single species, occupying a given area at the same time.
Smallest Unit that evolves. |
Species: | A kind of organism, interbreeding and genetically distinct. Given a binomial name (genus and species). Discrete (separate, unique) unit in nature. |
Gene Pool: | Total aggregate of genes (all the alleles) of all individuals in a population at one time |
Hardy Weinberg Theorem: | Describes a non-evolving populations….. 5 conditions for a population to be non-evolving: very large population size, no migration, no net mutations, random mating, no natural selection |
To calculate alleles (p+q=1)... | Where p= frequency of allele A (dominant allele).
Where q= frequency of allele a (recessive allele). |
To calculate frequency of genotypes... | ...p^2 + 2pq + q^2 = 1 |
Microevolution: | Small scale evolutionary change, know the 5 causes; genetic drift, gene flow, mutation, nonrandom mating, natural selection. |
Genetic Drift: | Changes in gene pool of a small population. Shifts randomly and by chance. |
2 Kinds of Genetic Drift: | 1. Bottleneck Effect- Catastrophes
2. Founder Effect- A few individuals colonize new habitat. |
Genetic Variation: | (The raw material for natural selection): 2 causes: mutations (occur randomly) and sexual recombination. |
Gene Flow: | Exchange of genes between populations. |
Mutation: | A change in DNA base sequences; causes all heritable "variations."
The raw material for natural selection. |
Natural Selection (of Micro-evolution): | Can cause evolution via differential reproductive success.
Relative fitness: leaves more viable offspring than others. |
Nonrandom Mating: | Cause evolution by shifting the frequencies of genotypes in a gene pool. |
2 Kinds of Nonrandom Mating: | Inbreeding- Individuals of a population tend to mate with close neighbors.
Assortative Mating: Individuals mate with partners that look like each other. |