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

Law 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