evolution unit

darwins observations

• species vary locally

• species vary globally

• species vary over time

acquired characteristics

traits altered by an organism during its life

patterns porting darwin’s theory

• closely related but different

• distantly related but similar

homologous structures

structures that are shared by related species and have been inherited from a common ancestor

analogous structures

body parts that share common functions but not structures

vestigial structures

inherited from ancestors but have lost most or all of their original functions

adaption

heritable characteristic that increases an organisms ability to survive and reproduce in its environment

natural selection

individuals have natural variations in their heritable traits, some variations were better suited to live in a certain environment then others

fitness

how well an organism can survive and reproduce in an environment

high fitness

individuals with adaptations well suited to the environment can survive and reproduce better

low fitness

individuals that are not well suited to their environment either die without reproducing

survival of the fittest

the difference in rates of survival and reproduction

descent with modification

living species are descended with modification

common descent

all life on earth shares a common genetic origin

gene pool

common group of genes

allele frequency

number of times an allele occurs in a gene pool

sources of genetic variation

• mutations

• genetic recombination during sexual reproduction

• lateral gene transfer

mutation

change in the genetic material of a cell, they can lower fitness by causing death or decreasing ability to reproduce

neutral mutations

don’t change organism genotype

low