APES Speciation and Natural Selection - Shope

• natural selection
o the principle that characteristics of species are determined by environmental conditions
- gradualist model = “slow change”
- punctuated equilibrium = “sudden change”

• adaptive radiation
o species evolving to fill niches (often following mass extinction)

• microevolution
o small genetic changes in a population

• macroevolution
o long term, large-scale changes

• background extinction (natural extinction)
o natural elimination of a species
o usually 1 – 10 species per year

• mass extinction
o widespread global extinction
o 25% - 75% of all species

• speciation
o development of 2 or more species from one ancestor
o geographic isolation: a population becomes divided by geologic events and evolves into different species
o reproductive isolation: within a population, genetic mutations prevent breeding

• genetic persistence
o retention and transfer of DNA material throughout time

• gene pool
o sum total of genes possessed by an individual or population

• coevolution
o 2 or more species interacting and causing each to change