AP Bio Unit 7

the 5 agents of evolutionary change

the 5 agents of evolutionary change

1. mutation

2. gene flow

3)non-random mating

4)genetic drift

5. selection

evolution

the change in the genetic makeup of a population over time

natural selection

a process where organisms having adaptations suited for a particular environment have a greater chance of survival and reproduction

competition

when organisms struggle with other organisms to get limited resources

variation

genetic differences among organisms

sources of variations

mutations and sexual reproductions

adaptation

traits that provide an advantage

fitness

ability of an organism to survive and produce fertile offspring

reproductive success

production of offspring

heritability

ability to pass on adaptations to next generations

stable environment

environment that is more constant or changes slowly over time, less likely that populations evolve

fast changing ecosystems

when environments experience major disruptions/change quickly, populations are more likely to evolve

genetic variation

the genotypic and phenotypic differences between individuals in a population

selective pressure

any biotic or abiotic factor influencing survivability

artificial selection

process by which humans select desirable traits in other species and selectively breed individuals with the desired traits

convergent evolution

where similar environmental conditions select for similar traits in different populations

analogous structure

traits that can be observed in distantly related or unrelated species a

mutation

a random change in an organisms genome

genetic drift

the random change in the frequency of a particular allele within a population

bottleneck effect

when a population drastically reduces size and genetic variation, can contribute to genetic drift

founder effect

random process that reduces genetic variation within a small population due to seperation from a large population

gene flow

movement of individuals between populations causing an exchange of alleles between populations

geographical evidence

evidence based on characteristics of habitat or land area

geological evidence

based on environment features of the earth over time

physical evidence

based on phenotype of species

biochemical evidence

based on chemical composition of living things

mathematical evidence

based on calculations of equations and statistics

morphological homologies

represent modified traits shared among different species

homologous structures

same internal structure but different function, shows common ancestor

vestigial structures

a body structure that is no longer needed or used

species

a group of individuals that can interbreed and produce viable offspring that can continue to reproduce

behavioral isolation

species have different courtship behaviors

mechanical isolation

reproductive structures have special adaptations to prevent successful mating and reproducing

gamete isolation

sperm of one species is not able to fertilize the eggs of another due to receptor shape issue

postzygotic barriers

prevent a zygote from developing into a viable, fertile offspring

hybrid inviability

mating results in a zygote but incompatibility may stop the development of a zygote

hybrid sterility

a hybrid is born that is vigorous but sterile

hybrid breakdown

first generation hybrids viable and fertile but second generations are feeble or sterile

habitat isolation

different habitats don’t allow breeding to occur

temporal isolation

species breed during different times of the year

prezygotic barriers

barriers that prevent the production of a fertilized egg

punctuated equilibrium

evolution occurs rapidly after long period of stasis, sudden changes in environment

gradualism

evolution occurs slowly over long periods of time because environment changes slowly

adaptive radiation

evolution of new species that allow empty ecological niches to be filled

allopatric speciation

species are created due to being isolated by a geographical barrier

sympatric speciation

happens with evolution of the new species due to individuals being reproductively isolated from surviving species

extinction

when a species becomes wiped out and no longer can produce offspring

speciation

new species form

niche

job or role an organism plays

deleterious trait

trait becomes less numerous a

adaptive trait

trait becomes more numerous