Chapter 23 & 13 Flashcards
Genetic Variation
Variation in heritable traits, a prerequisite to natural selection
Gene
Unit of heredity
Allele
A form of genes
Homozygote
Possessing two of the same alleleH
Heterozygote
Possessing different alleles (Dd, Bb)
How does mutation influence genetic variation
Mutation is a difference in DNA, which when replicated causes a change in the alleles
Asexual reproduction
Reproduction without fusion of gametes, based on mitosis
Homologous Chromosomes
A pair of chromosomes with the same genes, one copy from each parent.
Independent Assortment
Random distribution of homologous chromosomes during meiosis
Mitosis
The division of cells in a way where two genetically identical diploid cells are made
Meiosis
Two divisions of a cell where four genetically unique haploid cells are made.
What phases of Meiosis does Independent Assortment happen in
Metaphase I & II
Crossing Over
Homologous chromosomes exchanging reciprocal portions of themselves
Random Fertilization
The random mating of subjects in a population.
Species vs Population
Populations are a localized group of interbreeding individuals, species are groups capable of sharing alleles with oneanother
Directional Natural Selection
Average phenotype of a population changes in one direction
Disruptive
Eliminates phenotypes near the average value
Stabilizing NS
Reduces both extremes in the population, and no change in the average value (genetic variation is reduced)
Genetic Drift
Random changes in allele frequency; may cause fitness to decrease
Founder Effect
Change in allele frequencies occuring when a new population is established
Bottleneck Effect
A reaction to the number of alleles present in a population; certain alleles overrepresented among survivors.
Gene flow
Movement of alleles into or out of a population due to the movement of fertile individuals.
Frequency-Dependent selection
Oscillation of two averaged phenotypes
Heterozygote Advantage
when individuals with two different alleles (heterozygotes) for a particular gene have a higher fitness than those with two identical alleles
