ch 21: Natural Selection Flashcards
Microevolution
Change in allele frequencies of a population over Generations (small scale)
Sources of new alleles (allows evolution to occur)
- Mutations
- point and chromosomal - Sexual Recombination
- Crossing over, ind assorting, and fertilization
Population Genetics
Study of how population genetics change over time
Population
A group of individuals of the same species that live in the same area an interbreed (offspring must be fertile)
Gene Pool
all alleles for all genes for all members of a population (variation in the population)
Allele Frequency
the frequency at which an allele exists in a population
Fixed Allele
when all members are homozygous for the same allele
The Hardy-Weinberg Theorem
explains how allele frequencies (genotypes) change over time
Hardy-Weinberg Equilibrium
a tool to measure change, Hardy-Weinberg equilibrium describes the constant frequency of alleles in such a gene pool
5 conditions for non-evolving populations are rarely met in nature
- Extremely large population size
- No gene flow
- No mutations
- Random mating
- No natural selection
Events that alter a population’s genetic composition
Natural Selection
Genetic Drift
Gene Flow
Natural Selection
differential selection
Genetic Drift
(unpredictable fluctuations in allelic frequency from one generation to the next) Chance, random, nonadaptive, small pop = greater impact of allele change
2 types of genetic drift
population bottleneck
The Founder Effect
population bottleneck
the seals((big populations to little populations to big populations)