ap bio unit 7 (evolution/natural selection)

bioevolution

change in genetic makeup of a species over time

microevolution

over long periods of time, there evolves a new species; species branch based on environments

sexual dimorphism

males and females look different for mating reasons (e.g. flashy colors in male parrots)

directional selection

selection occurs in direction of an extreme (e.g. giraffes evolved really long necks so they could get food)

disruptive selection

selection occurs in direction of both extremes (e.g. getting both light and dark but not neutral skin colors to camoflauge)

stabilizing selection

selection occurs in direction of moderate trait (e.g. getting egg clutch size just right so it is not too large or small)

adaptive radiation

organisms diversify/evolve rapidly to adapt to a major environment change

species

1. can have offspring

2. offspring can reproduce

   horses and donkeys are not the same species

sympatric speciation

when a species evolves into two when there are no geographic barriers between the groups. incompatibility can happen due to different ploidy and different seasonal mating habits

allopatric speciation

when a species evolves into two due to geographic barriers btwn the groups

prezygotic barrier

no fertilization happens (e.g. geo barrier)

postzygotic barrier

there is fertiliziation but no viable, fertile offspring (e.g ploidy issues)

selective pressures

factors that increase or decrease reproductive success in a population

sexual selection

can favor traits that decrease survival (eg bright colors in males = getting laid)

superposition

younger rock is deposited on old

radiometric dating

C14 half life used to find rock age

biogeography

related species are in same geographic region

convergent evolution

evolving similar traits due to environmental pressures (e.g. everything in the arctic is white)

vestigial structures

things that had important function but not anymore (e.g. whale femur)

homologous structure

structures in different species that are similar because of similar ancestry (e.g. all tetrapods have same limb structure)

homoplastic structures

similar structures that evolved independently in two species (e.g. bat and butterfly wings)

comparative embryology

looking at early embryos can reveal info that you can’t get from adults (humans and fish both have tails)

endosymbiotic theory

the mitochondria and the cell combined to have a symbiotic relationship (mitochondria used to be its own prokaryote, evidence of evolution)

homeobox

a gene sequence that regulates embryo development in many different species (common ancestor theory)

autophagy

removes broken cell component (evolved as mitochondria quality control)

extinction

leads to rapid speciation, biodiversity up, extinction down

origin of life model

1. limited O2

2. organic molecules from asteroid

3. monomers fused to become polymers

4. methane + atmosphere + electricity = hydrocarbons

gene flow

when organisms migrate and reproduce (leave or enter)

gene drift

chance event changes allele frequencies in pop (minimized by large pop)

bottleneck effect

population decreases due to natural disaster or something (pop is no longer as diverse)

founder effect

some of the population goes off and forms a colony that is not always representative of the main group

hardy-weinberg equilibrium

lets us take a snapshot of the allele makeup of a population at a given time

p²+2pq+q²=1

p+q=1

p = dominant allele frequency

q = recessive allele freq.

quadratic equation → phenotype frequencies

(always start w/ recessive phenotype and solve from there)

hardy-weinberg conditions

no natural selection

no mutation

no gene flow/migration

large population

random mating

clade

a group with a common ancestor and ALL of its descendants

outgroup

more distantly related group that serves as a reference point

shared character

trait that two lineages have in common

derived character

one that evolved in the lineage leading up to a clade and sets apart members of that clade from other individuals

maximum parsimony

the tree with the fewest number of evolutionary changes (new shared/derived traits) is the most likely explanation (e.g. one clear outgroup)