life sciences- evolution unit

homozygous dominant

carries both dominant alleles

heterozygous

carry both alleles, only dominant exprfessed

homozygous recessive

both recessive alleles

carrying capacity

max population that an environment can indefinitely support

evidence of evolution

fossil fuels, comparative biochemistry, comarative embryology, comparative anatomy, geography

fossil records

reveals existence of species that have befome extinct or have evolved

comparative biochemistry

organisms have similar biochemical pathways

comparative embryology

organisms have similar stages in embryotic development

geography

distribution of species through geography sugges todays forms evolved from ancestors

homologous structures

similar structures, different function (suggests common ancestry

analogous structures

different structure, similar function (suggests adaptation)

vestigial structurets

evidence that structures evolved

sexual selection

selection based on variation in sexual characterisics

stabilizing selection

eliminates extremes of a population and favours common forms

disruptive selection

increases extremities and eliminates common forms

directional selection

a phenotype replaces another in the gene pool

artificial selection

human selected traits in plans and animals are bred

hardy weinberg equilibrium

population must be very large (no genetic drift), must be isolated from other populations (no migration), no mutations, random mating, no natural selection

5 fingers of evolution

Small Population (Pinky), Non-Random Mating (Ring), Mutation (Middle), Gene Flow (Index), and Natural Selection (Thumb)

genetic drift

change in gene pool due to chance

bottleneck efffect

natural disasters reduces size of population unselectively

founder effect

small population breaks from larger one to colonize new area

gene flow (migration)

movement of alleles into or out of a population

mutations

changes in genetic material

non random mating

individuals choosing mates for a specific reason eliminating less fit individuals

natural selection

survival of fittest

balanced polymorphism

presence of 2 or more phenotypically distinct forms of a trait in a single population of a species with each morph having a distinct advantages from adapting for life in a different area

geographical variation

population may show different adaptations based on abiotic factors or weather conditions

sexual reproduction

provides shuffeled alleles and recombinations during meiosis

outbreeding

mating within one species of an organism that are distantly related

diploidy

having 2n hides a large allele pool that may be harmful but possibly advantageous when condition change

heterozygote advantage

preserves multiple alleles within a population since it has the dominant and recessive alele

frequency dependant slection

minority advantage decreases frequency of common phenotypes when predators prey on general/common prey

evolutionary neatural traits

traits that have no selective advantatge

allopatric speciation

caused by geographical isolation

polypoidy sympatric speciation

when a cell has more than 2 complext sets of chomosomes, functionally isolated bc cant bread with 2n organisms

habitat isolation

2 organisms of the same area dont interact

behavioural isolation

mating behaviour that leads to reproduction or lack of reproduction

temporal isolation

activity depends on time of year

reproductive isolation

differences in genitalia/flower shape. pre/postzygotic happens before or after reproduction can occur. postzygotic prevents fertile offspring

divergent evolution

when population becomes isolated from other species - exposed to new selective pressues, evovleves into new species

convergent evolution

when unrealted species live in the same environmnet face similar pressures, giving them similar characteristscs

parallel evolution

describes 2 related species which have made similar evolutionary adaptations after coming from a commen ancestor

coevolution

A change in one species acts as a selective pressure, causing a genetic or evolutionary response in the other, and vice versa

adaptive radiation

emergence of numerous species from a common ancestor introduced to a new environment

what do p and q represent in hardy weiner

p = dominant, q = recessive

lamarck significance

first to propose common ancestors, evident in fossil fuels, hypothesiszed that acquired traits are passed on to offspring.

darwin significance

species modified by natural selection

malthus significance

human population has potential to exponentially grow but cant because of envionmental conditions