Population Genetics Flashcards
Genotypic Frequency
- Proportion of a particular genotype within a population.
Mendelian Population
- A group of interbreeding, sexually reproducing individuals that have a common set of genes.
Allelic Frequency
- Proportion of a particular allele within a population.
Genetic Rescue
- Introduction of new genetic variation into an inbred population in an effort to improve the health of the population and better ensure its long-term survival.
Gene Pool
- Set of all genes in a population.
Hardy-Weinberg Law
– Principle of population genetics stating that if a population is large, randomly mating, and not affected by mutation, migration, or natural selection, then allelic frequencies of a population do not change and the genotypic frequencies stabilize after one generation in the proportions p2 (the frequency of AA), 2pq (the frequency of Aa), and q2 (the frequency of aa), where p equals the frequency of allele A and q equals the frequency of allele a.
Hardy-Weinberg Equation
p2 + 2pq + q2 = 1
Hardy-Weinberg Equilibrium
- Frequencies of genotypes when the conditions of the Hardy–Weinberg law are met.
Degrees of freedom for a chi-square test of Hardy-Weinberg equilibrium
The number of genotypes – the number of alleles
Inbreeding
- A form of non-random mating; preferential mating between related individuals.
Inbreeding Depression
- Decreased fitness arising from inbreeding; often due to the increased appearance of lethal or deleterious traits with inbreeding.
Non Random Mating
- When the probability that two individuals in a population will mate is not the same for all possible combinations of genotypes.
Sampling Error
- Deviations from expected ratios due to chance when the sample size is small.
Genetic Drift
- Change in allelic frequencies due to a sampling error.
Migration
- Movement of genes from one population to another; also called gene flow.
Mutation As An Evolutionary Force
-Creates new genetic variation in a gene pool.
Founder Effect
- Sampling error that results from the establishment of a population by a small number of individuals; leads to genetic drift.
Effective Population Size
- Effective number of breeding adults in a population; influenced by the number of individuals contributing genes to the next generation, their sex ratio, variation between individuals in reproductive success, fluctuations in population size, age structure of the population, and whether mating is random.
Genetic Bottleneck
- Sampling error that arises when a population undergoes a drastic reduction in size; leads to genetic drift.
Selection Coefficient
- Measure of the relative intensity of selection against a genotype; equals 1 minus W (fitness value).
Directional Selection
- Selection in which one allele or trait is favored over another.
Overdominance
- Selection in which the heterozygote has higher fitness than either homozygote; also called heterozygote advantage.
Fitness
- Reproductive success of a genotype relative to that of other genotypes in a population.
Natural Selection
- Differential reproduction of individuals with different genotypes.
Underdominance
- Selection in which the heterozygote has lower fitness than either homozygote.
Fixation
- When one allele reaches a frequency of 1 in a population, at which point all individuals in the population are homozygous for one allele.
