Natural selection

Mutation

Nonrandom mating

Gene Flow

Genetic Drift

Results from differential reporductive success' success with individuals with particular phenotype, individuals vary, more individuals than resources can support, struggle for existence, individuals with best adaptions pass advantages to offspring, adaptions become more common

Founder effect- small group of individuals form new population.

Bottleneck effect - members of population die leaving on a few survivors

Directional Selection

Disruptive Selection

Stabilizing Selection

Most Common

Extreme phenotypes are less than the optimal intermediate phenotype

Macroevolution-large complex changes

Microevolution-short term changes in allele frequencies within a population or species, occurs much smaler scale

Carlolus Linneaus

2 main names used to classify organism

Designed hierarchical system of classification.

Genus and species

ex. Homo sapiens

Allopatric speciation - geologic event or structure physically seperates population in 2 groups.

Parapatric speciation - part of a population enters a new habitat bordering the range of the parent species.

Sympatric seciation - population diverge genetically while living in the same physical area.

Prezygotic Barriers -  prevent fertilization.

ecological or habitat isolation, temporal Isolation - (timing differences),behavioral isolation (intricate mating dances), mechanical isolation (reproductive anatomy), gametic isolation (external fertilization)

Postzygotic Barriers - prevent viable or fertile offspring.

Hybrid inviablity (embryo dies early), hybrid infertility (mules are infertile)

Graduated - evolution proceeds in small, incremental changes over many generations.

Punctuated Equilibrium - long periods of statis alternates with relatively brief bursts of fast evolutionary change between them.

Individuals colonizing new isolated habitat

Some members of a population inherit a selective advantage (new trait)

Survive major environmental change

Failure to adapt to environmental change

Habitate loss

New predators

New diseases

Bad luck

How fast the environment is changing relative to the rate the population evolves

Impact theory - meteorite/comet crash sends debris blocking sunlight.

Plate tectonics - dramatic enviromental from moving of Earth's crust profoundly affected life

Evolutionary tree or Phylogenies

depicts a species relationships based on descent from common ancestors

Branching indicates divergence

Discontinuation is extinction

Angle of branch point indicates gradualism or punctuated equilibrium

Orginally derived from fossil data

Newer molecular data based on mitochondrial DNA

Paleontology

Era - Cenozoic

Period - Quatinary

epoch - Recent

Study of distribution pattern of species across the planet

Homologous Structures