Mechanisms Of Evolution Flashcards
What is a point mutation
When one DNA base pair changes
What is gene duplications?
Small duplication of a gene can occur, resulting in a family of similar genes
What are the five reasons why populations don’t stick to hardy Weinberg equilibrium?
- Genetic drift. (populations are usually small and therefore genetic drift occurs)
- Gene flow does occur between populations.
- Mutations can occur.
- Random meeting is rare in breeding occurs.
- Natural selection.
Define natural selection
Differential success and reproduction that results in certain alleles being passed to the next generation more frequently
What is adaptive evolution and what causes it
Adaptive evolution is evolution, driven by an improvement in the match between an organism and their environment
What is polymorphism?
When there are two or more distinct forms in a population because of genetic differences
How can genetic variation be measured?
As gene variability or nucleotide variability.
What is relative fitness
The contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals
What are the three modes of Natural Selection?
- Directional selection when an extreme phenotype is favoured over others.
- Disruptive selection when phenotypes on both extremes are favoured against the average.
- Stabilizing selection, intermediate variance favoured against extreme phenotypes.
What is sexual dimorphism?
Marked differences between the sexes and secondary sexual characteristics
What is the difference between intrasexual selection and intersexual selection?
Intersexual selection is a direct competition among individuals of one sex mates of the opposite sex. Like when box fight over breeding privilege.
Intersexual selection is the same as mate choice. It occurs when individuals of one sex are choosey and mate selection.
What is balancing selection?
When natural selection maintains stable frequencies of two or more phenotypic forms in a population
What two forms does balancing selection include
Frequency, dependent selection and heterozygote advantage
Define frequency, dependent selection
When the fitness of a phenotype declines, if it becomes too common in a population
Define heterozygote advantage
Occurs when heterozygote have a higher fitness then do both homozygotes
