Population Evolution

Front 1

point mutation

Back 1

change in a gene at a single nucleotide pair

Front 2

heterozygote advantage

Back 2

Greater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools

Front 3

selection coefficient

Back 3

difference between two fitness values, representing a relative measure of selection against an inferior genotype

Front 4

nonadaptive genetic drift

Back 4

a change in a population’s allele frequencies due to chance
-founder effect
-bottleneck effect

Front 5

pleiotropy

Back 5

ability of a single gene to have multiple effects

Front 6

Frequency-dependent selection

Back 6

decline in the reproductive success of a morph resulting from the morph’s phenotype becoming too common in a population; a cause of balanced polymorphism in populations

Front 7

gene flow

Back 7

loss or gain of alleles in a population due to the migration of fertile individuals or gametes between population

Front 8

stablizing selection

Back 8

natural selection that favors intermediate variants by acting against extreme phenotypes

Front 9

Batesian mimicry

Back 9

type of mimicry in which a harmless species looks like a species that is poisonous or otherwise harmful to predators
ie butterflies

Front 10

Hardy-Weinberg equilibrium

Back 10

condition describing a nonevolving population (one that is in genetic equilibrium)
Conditions:
1. Large Population
2. No migration .
3. No net mutations
4. Random mating .
5. No natural selection

Useful for estimating prevalence of certain alleles given phenotype info

Front 11

bottleneck effect

Back 11

genetic drift resulting from the reproduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population

Front 12

prezygotic barriers

Back 12

1. habitat isolation
2. behavioral isolation
3. temporal isolation
4. mechanical isolation
5 gametic isolation (gametes dont form zygote)

Front 13

postzygotic barriers

Back 13

1. reduced hybrid viability
2. " " fertility
3. hybrid breakdown: offspring can't reproduce
-grandchildren of cross breed that can't reproduce

Front 14

allopratric speciation

Back 14

phenomenon whereby biological populations are physically isolated by an extrinsic barrier and evolve intrinsic (genetic) reproductive isolation, such that if the barrier should ever vanish, individuals of the populations can no longer interbreed

Front 15

sympatric speciation

Back 15

same place/ no barrier
-more common in prokaryotes