chapter 23 Flashcards
how does hardy-weinberg describe evolution?
change in the allele frequency in a population over time.
how does hardy-weinberg describe a gene pool?
all of the alleles from the organisms in a population
in a population p means
frequency dominant allele
in a population q means
frequency recessive allele
p+q=__
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what is hardy-weinberg equilibrium
when a populations allele frequency doesnt change
what conditions are required for hardy-weinberg equilibrium to occur?
-no mutations
-no migration
-large gene pools
-random mating
-no selection
what is gene flow?
movement of alleles between populations
what is the bottleneck effect?
a type of gene drift. large loss of population due to death (natural disasters, disease, loss of habitat, decrease in genetic diversity due to chance)
what is the founder effect?
a type of gene drift. small sample of gene pool break away and colonize new population (loss of genetic diversity)
what is stabilizing selection?
a form of natural selection that occurs when the intermediate can improve the adaptation of the population (extreme phenotypes are selected against)
what is directional selection?
a form of natural selection that occurs when an extreme phenotype is favored (distribution curve moves in one direction)
what is disruptive selection:
a form of natural selection. two or more extremes are favored over the intermediate phenotype
what is sexual selection
A form of other selection. Adaptive changed in males and females that lead to an increased ability to secure a mate
what is male competition?
a form of other selection where males must compete for attention of the female
what is female choice?
a type of other selection where females produce less eggs than men do sperm, much more time and effort has to be put into young, must be choosy
what is sexual dimorphism?
a type of other selection where there are distinct differences in size or appearance between the sexes of an animal
what is exaptation?
natural selection evolves previous trait for new use (example: feathers were first used for thermoregulation, then evolved to help dinosaurs fly)
what is other selection?
evolution doesn’t produce perfect adaptations; it works with the mutations available, and adaptations may not always be perfect
example of other selection
Human vertebrae evolved when ancestors walked with their bodies parallel to the ground. prone to injury
what is heterozygous advantage?
heterozygous genotype has some phenotypical advantage somewhere else in the body (example: sickle cell)
