AP Bio - Unit 7: Evolution (mechanics of evolution)

Law of Evolution

The change in the genetic allele frequency of a population over time resulting in a change in phenotypic characteristics

Allele Frequency

The incidence of gene varianceThe incidence of gene variance

5 Mechanisms of Evolution

Natural selection, mutation, gene flow, sexual selection, and genetic drift

what is natural selection

* happens at a INDIVIDUAL LEVEL
* the adaptive trait (trait that promotes survival) persists
* 4 conditions for natural selection (VOIDs)
* Varience: differences due to random fertilization, crossing over, and independent assortment
* Overpopulation: more of one species means some will have to die and the adaptive trait will become more prominent
* Inheritance: parents pass on genes
* Differential Survival: the struggle for existence means advantageous characteristics survivethe struggle for existence means advantageous characteristics survive

Fitness

reproductive success

Selection Pressure

Force that causes a population to evolve. The stronger it is the more change there is

Mutation

a random change in DNA

Gene Flow

The transfer of genes between different populations e.g. migration

Sexual selection

The selection of a mate based on phenotypic characteristics

e.g. peacock feathers

Genetic Drift

Chance event that causes change in SMALL POPULATIONS

2 types:

* Bottleneck effect
* Sudden disaster that happens to pick survivors with different alleles
* Founder effect
* A few individuals from one population start a new population and therefore change the allele frequencyA few individuals from one population start a new population and therefore change the allele frequency

Evidence of Evolution

* fossil record analysis
* molecular evidence
* experiments
* observation
* comparative anatomy (homologous vs analogous)
* artificial selection (breeding)
* comparative embryology
* biogeography