Microevolution Quiz

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gene flow

moving alleles through populations

speciation

breeding between populations stops when there is enough genetic drift between them

genetic drift

random changes in allele frequencies, not due to fitness, small populations are more susceptible

bottle neck effect

genetic diversity is greatly decreased due to a random event killing a portion of the population (greater risk of genetic disorder, traits can be lost)

founder effect

a new population is started that only has a couple organisms form a previous population

coevolution

when species become interconnected and cause each other to evolve

evolutionary pressure

something that increases or restrics evolutionary success

convergent evolution

2 species that are not closely related but develop similar traits because they have similar environmental pressures

divergent evolution

2 species have similar ancestors but build differences that lead to evolution of 2 different species

adaptive radiation

many common ancestors, branch of divergent evolution

allopatric speciation

populations are separated by a physical barrier, the two populations can’t mate because of the barrier (random mutations and selective pressures make speciation)

sympatric speciation

reproductive isolation in a subpopulation not due to a physical barrier (unable to breed because of a pre-zygotic or post-zygotic barrier)

habitat isolation

two species live in the same geographic area but occupy different habitats and rarely encounter each other

temporal isolation

mates at different times, during night or day, summer or winter

behavior isolation

mating behavior (swims, flies, dances)

mechanical isolation

physically can not breed (bird and horse)

gametic isolation

the sperm can’t fertilize the egg

reduced hybrid vitality

the animal doesn’t live long enough to reproduce

reduced hybrid fertility

the offspring can’t have kids

hybrid breakdown

the first generation can have offspring, the second generation can, but the third generation can’t

stabilizing selection

any selective force or forces which push a population toward the average, or median trait

directional selection

individuals with traits on one side of the mean in their population survive better or reproduce more than those on the other

disruptive selection

when more extreme phenotypes (or genotypes) within a population have a fitness advantage over intermediate individuals