Studied by 14 peoplegene 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
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Flashcard (49)