Chapter 15 Flashcards
Evolution
Descent with modification
population
a group of interbreeding organisms of the same
species
allele frequency
(# of copies of an allele)/(total # of alleles for the same
gene in the population)
Gene Pool
the entire collection of genes and alleles within a
population
Artificial selection
human chooses desired features, then allows only the individuals that
best express those qualities to
reproduce
natural selection
environmental
factors cause the differential
reproductive success of
individuals with particular
genotypes
Factors that change allele frequency over time
- natural selection
- mutation
- genetic drift
4.nonrandom mating
5.migration
Adaptations
heritable traits that provide a selective advantage
because they improve an organism’s ability to survive and
reproduce
fitness
an organism’s contribution to the next generation
directional selection
one phenotype is favored to another
disruptive selection
extreme phenotypes are favored
over an intermediate phenotype
stabilizing selection
an intermediate phenotype is favored
over the extreme phenotypes
Genetic drift
occurs
purely by chance; most
common in small
populations
founder effect
when only a
few individuals establish a
new population, allele
frequencies may change
population bottleneck
occurs if a disaster drastically reduces
the size of a population
sexual selection
a type of natural selection
resulting from variation in the ability to obtain mate
migration
moves alleles between populations
Hardy-Weinberg equilibrium:
unlikely situation in which allele
frequencies do not change between generations
null hypothesis
states that allele
frequencies do not change from one generation to the next
when is the Hardy-Weinberg equilibrium met (5 things)
- no natural selection
- no mutations
- population is large enough to eliminate random changes in allele frequencies
- no random mating
- no migration
Hardy-Weinberg equation
p+q= 1
p^w+2pq+q^2
where p=frequency of dominant allele
where q= frequency of recessive allele
