Unit 7 Flashcards
Evolution
The change in gene frequencies within a population over time
Natural selection
traits that enhance survival allow for organisms to better live and reproduce, pushing for traits to be selected and more common
Darwin’s postulates for natural selection
- variation is within populations
- some variations are heritable
- organisms over-reproduce
- different survival based on traits
Evolutionary fitness
the ability an organisms has to survive and reproduce
Reproductive success
how well an organism is able to create offspring that can survive to reproductive age
Directional selection
change in a population’s phenotype or genotype overtime away from what the mean is in the environment
Disruptive selection
causes two extreme versions of a trait
Stabilizing selection
selection where the average and moderate phenotypes are selected for, and the extremes start to go away
Genetic Variation in a population
natural genetic differences among organisms part of the same species and population.. allows for population to better survive
Phenotypic variation in a population
variation in appearances of organisms, can be considered a combination of genotypic and environmental variations.
like genotypic variation, it is important in helping populations survive when changes occur
Artificial selection vs natural selection
artificial selection happens because external factors such as human purposefully influence the traits that are selected, eg. dog breeding
natural selection does not have such interventions
Mutation
change DNA sequences
Genetic drift (bottleneck effect and founder effect)
genetic drift is a random change in the allele frequencies in a gene pool
bottleneck effect is when a large part of the population is destroyed so the gene pool decreases and the consequent generations have lesser genetic variation
founder effect is when individuals from a population are separated from the rest of the population and thus only carry a small unrepresentative section of genes
Migration
movement of individuals or populations across different regions that can also cause gene flow
Gene flow
movement or exchange of genes from different populations
5 conditions for Hardy weinberg equilibrium
- no mutations
- no gene flow
- a very large population
- random mating
- no natural selection
Allele frequency
what the frequency or how common an allele is in a population
Genotype frequency
proportion of different genotypes in a population
Geographical evidence
distribution of species all over the world to understand evolution
Molecular evidence
DNA and protein sequences that show proof of evolution
Extant and extinct organisms
extant organisms are ones that are still alive and exist
extinct organisms are ones that completely died
Fossils
preserved remains of ancient organisms
Sedimentary rock
rocks formed from cementation of sediments
Radiometric dating including Carbon-14 dating
used to determine age of organic materials