Topic 7: Evolution of Populations Flashcards
Microevolution
the change in allele frequency in populations over generations
Allele
different form of a gene.
Mutations
Changes in an individuals DNA sequence. Caused by chromosomal errors of structural damage. Creates new alleles.
Chromosomal Mutations
Delete, disrupt or rearrange many loci.
Duplication Mutations
Increases genome size
Sexual Reproduction
Amplifies genetic variation by creating new combinations of existing alleles. Recombination during meiosis.
Adaptive Evolution
A population becomes more adapted to its environment under natural selection.
Relative Fitness
the contribution an individual makes to the gene pool of the next generation.
Directional Selection
One extreme phenotype has a higher fitness than the other end.
Disruptive Selection
Favours both extreme ends pf the phenotypic range, often leads to divergent phenotypes.
Stabilizing Selection
Favours common phenotypes since they have a higher fitness. Reduces genetic variation.
Non-Adaptive Evolutions
a change in allele frequencies that does not lead a population to become more adapted to its environment.
Genetic Drift
Random changes in allele frequency in a population. Bottle neck effect, founder effect. More harmful on small population, reduces genetic variation.
Gene Flow
The movement of alleles between populations.
Bottle Neck Effect
a sudden reduction in population size due to a change in the environment.
The founder effect
A few individuals become isolated from their population and create their own small gene pool.
Balancing Selection
a form of natural selection that maintains genetic diversity by favouring stable frequencies of multiple alleles in the gene pool of a population.
Temporal or Spatial Variation
Changes in environment and location.
Heterozygote Advantage
an organism with two different alleles of a particular gene has a fitness advantage over an organism with two identical copies.
Frequency-Dependent Selection
The fitness of an allele depends on its frequency in the population. More common = less fitness.
