microevolution and natural selection 9/9-9/13

evolution

a change over time

units of evolution

population and species

population

a group of members of the same species living in the same place at the same time

species

a group of members that can breed and produce fertile offspring

charles darwin

created the theory of natural selection

natural selection

the mechanism that allows populations to become better adapted to the environment over generations

selection pressures

a change in environment that causes a need to adapt

components of natural selection

• populations are capable of producing large numbers of offspring

• variation exists within the offspring

• individuals struggle for existance

• differential inharitance of genes

ecosystem dynamics

the study of the relationships between organisms and their environment

selection pressure types

• biotic (living) factors

• abiotic (non-living) factors

biotic factor examples

• food webs

• food chains

abiotic factor examples

• pH levels

• weather

• climate

• geology

identified broad observations of adaptation

• unity of life

• diversity of life

• match between organisms and their environments

darwinian fitness

the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals

mode of selection

• stabilizing selection

• directional selection

• disruptive selection

stabilizing selection

the average individual is favored

directional selection

one extreme is favored

disruptive selection

both extremes are favored

artificial selection

when human beings modify other species by selecting and breeding them for desired traits