IB 150 - UNIT 3 Learning Goals Questions With Complete
Solutions
allopatric speciation Correct Answers allopatric: Gene flow is
interrupted when a population is divided into geographically
isolated subpopulations
process: Once geographic separation has occurred, the separated
gene pools may diverge through different mechanisms (natural
selection, genetic drift, gene flow). Different mutations arise,
natural selection acts on the separated organisms, and genetic
drift alters allele frequencies. Reproductive isolation may then
arise as a by-product of selection or drift having caused the
populations to diverge genetically
-pop or species that live in diff geographic areas - mating
physically impossible b/c geographic isolation
ex:// The water level in a lake may subside, resulting in two or
more smaller lakes that are now home to separated populations;
river may change course and divide a population of animals that
cannot cross it
-more common than sympatric
B.Discuss the consequences of differential survival and
reproduction for variation in a population. (Why is "survival of
the fittest" not capturing the whole story?) Correct Answers -
individuals have to be able to survive long enough to be able to
produce more offspring than some other individual with another
genotype -"survival of the fittest" doesn't take everything into
account, since individuals have to be able to 1.survive to
reproductive age 2.find/acquire a mate 3.reproduce -common
misconceptions about fitness: physical fitness of organism is the
, only factor in natural selection (this is only point 1; doesn't
account for points 2 & 3)
Calculate allele frequencies given genotype frequencies or
number of individuals with each genotype Correct Answers
allele frequency= times allele shows up in pop ÷ total # of
alleles in pop
genotypic frequency= # of individuals with a particular allele ÷
total # of individuals
Characterize how the biotic interactions of interspecific
competition and predation and abiotic factors of an organism's
environment result in selection pressures from that interaction
can that affect intraspecific competition of individuals of
different genotypes. (How do selection pressures affect natural
selection) Correct Answers -They are important because they
are what's causing the fitness differences between the traits.
-Interspecific- between species. All of these factors cause
selection pressures, predation, desert hot dry. All of these cause
intraspecific competition because they are the ones that are
going to be selected for in the population. -One allele makes you
faster, selection pressure is competition between cheetahs, fast
ones get to eat
Compare and contrast expected changes in allele frequency in a
population depending on if that allele is under selection vs.
experiencing drift Correct Answers Drift: changes in allele
frequencies in a population due to genetic drift is random and
due simply to chance.
Solutions
allopatric speciation Correct Answers allopatric: Gene flow is
interrupted when a population is divided into geographically
isolated subpopulations
process: Once geographic separation has occurred, the separated
gene pools may diverge through different mechanisms (natural
selection, genetic drift, gene flow). Different mutations arise,
natural selection acts on the separated organisms, and genetic
drift alters allele frequencies. Reproductive isolation may then
arise as a by-product of selection or drift having caused the
populations to diverge genetically
-pop or species that live in diff geographic areas - mating
physically impossible b/c geographic isolation
ex:// The water level in a lake may subside, resulting in two or
more smaller lakes that are now home to separated populations;
river may change course and divide a population of animals that
cannot cross it
-more common than sympatric
B.Discuss the consequences of differential survival and
reproduction for variation in a population. (Why is "survival of
the fittest" not capturing the whole story?) Correct Answers -
individuals have to be able to survive long enough to be able to
produce more offspring than some other individual with another
genotype -"survival of the fittest" doesn't take everything into
account, since individuals have to be able to 1.survive to
reproductive age 2.find/acquire a mate 3.reproduce -common
misconceptions about fitness: physical fitness of organism is the
, only factor in natural selection (this is only point 1; doesn't
account for points 2 & 3)
Calculate allele frequencies given genotype frequencies or
number of individuals with each genotype Correct Answers
allele frequency= times allele shows up in pop ÷ total # of
alleles in pop
genotypic frequency= # of individuals with a particular allele ÷
total # of individuals
Characterize how the biotic interactions of interspecific
competition and predation and abiotic factors of an organism's
environment result in selection pressures from that interaction
can that affect intraspecific competition of individuals of
different genotypes. (How do selection pressures affect natural
selection) Correct Answers -They are important because they
are what's causing the fitness differences between the traits.
-Interspecific- between species. All of these factors cause
selection pressures, predation, desert hot dry. All of these cause
intraspecific competition because they are the ones that are
going to be selected for in the population. -One allele makes you
faster, selection pressure is competition between cheetahs, fast
ones get to eat
Compare and contrast expected changes in allele frequency in a
population depending on if that allele is under selection vs.
experiencing drift Correct Answers Drift: changes in allele
frequencies in a population due to genetic drift is random and
due simply to chance.
