Chapter 23 Flashcards
(32 cards)
population genetics
study of genes + genotypes in a population
based on changes in the gene pool
gene pool
all alleles for every gene in the population
(can also be described
population
all the species in a pre-defined location
polymorphisms
having 2 or more versions of a trait in a population
monomorphic
only 1 trait
think teeth, etc
what can be mutated?
genone > chromosome > gene > base pair
most common mutation is SNPs
SNP
Single Neuleotide Polymorphism
a base pair change, accounts for 90% of all variation among humans
allele frequency
= # of specific allele/total # of alleles
if frequencies change, evolution is happening
genotype frequency
= # of specific genotype/# of all genotypes
if frequencies change, evolution is happening
punnett square
used to calculate what alleles, genotypes, and phenotypes we should get in the next generation
equillibrium
allele and genotype frequencies do not change from generation to generation
evolution
changes in genotypes over time in populations
Hardy Weinberg Equilibrium
p + q = 1
p2 + 2pq + q2 = 1
selection
differences in survival + reproduction between individuals exhibiting different phenotype
directional selection
changes the average value of a trait by selecting for one extreme
(slightly reduces overall population variation)
stabilizing selection
can change the average value of a trait by selecting for intermediate values
(greatly reduces overall variation)
disruptive selection
maintains the average value of a trait by selecting for both extremes
(greatly increases overall variation but doesnt affect the average)
balancing selection
2 or more alleles maintained in a population over time
artificial selection
aka selective breeding
the process of modifying organisms by selection in breeding controlled by humans
sexual selection
type of natural selection on traits that are directly involved with reproduction
*males with the “best” traits will reproduce more & pass traits on
natural selection will create differences:
- within species (microevolution)
- among species (maco-)
- between or within sexes within a species
intrasexual selection
male to male competition
intersexual selection
male to female competition
(when female is present, female choice)
genetic drift
change in allele freq. in adaptation due to chance variation in the survival + reproduction of individuals
(if its random, then its not adaptive)