Evolution

evolution

the change in populations over time

Charles Darwin

studied organisms and explained how they probably change over time.

How did fossil shape support the theory of evolution?

Shows similarities between extinct and modern species.

Artificial selection

breeding to get deliberate outcomes in offspring

adaption

evidence for evolution

Mimicry

allows a species to appear as another

camouflage

allows a species to blend with their surroundings

homologous structure

structural feature with a common evolutionary origin

analogous structure

do not have common evolutionary origin but are similar in function

vestigial structure

a body structure that has no function in a present day organism but was useful to ancestors

allelic frequency

when a population has a percentage with a certain trait...

gene pool

all the alleles of a population's genes

genetic equilibrium

the frequency of alleles remains the same over generations (Hardy-Weinburg Principle: p^2 2pg+g)

mutations

changes in genetics or alleles, which changes genetic equilibrium. Caused by environmental factors and can be lethal.

genetic drift

mechanicism that disrupts a population genetic equilibrium (due to isolation reproduction)

gene flow

migrating individuals into and out of population can disrupt genetic equilibrium

stablizing selection

natural selection that favors average individuals in a population (not too big, not too small)

directional selection

natural selection favors one of the extreme variations of a trait (big or tiny)

disruptive selection

individuals with either extreme of a trait variation is selected for. this eliminates the intermediate phenotype.

speciation

the evolution of new species. it occurs when members of a similar population can no longer interbreed to prduce fertile offspring within their natural envirnoment.

geographical isolation

occurs whenever a physical barrier divides a population. population is therefore smaller. new species can evolve.

reproductive isolation

occurs when formerly interbreeding organisms can no longer mate and produce fertile offspring.

polyploid

any species with multiple of the normal set of chromosomes. occurs when mitosis and meiosis makes a mistake. polyploids can mate w/ other polyploids and could form a seperate species.

gradualism

the idea that species originate through a gradual change of adaptations.

punctuated equilibrium

argues that speciation occurs quickly in rapid bursts along with long periods of genetic equilibrium in between

adaptive radiation

when an ancestrial species evolves into an array of species to fit a number of diverse habitats.

divergent evolution

the pattern of evolution in which species that once were similar to an ancestrial species diverge or grow apart.

convergent evolution

a pattern of evolution in which distantly related organisms evolve similar traits. occurs when unrelated species occupy similar environments in diff. parts of the world.