Bio 322- Exam 2 Practice Questions With Complete
Solutions
A female fig wasp arrives at a fig to lay her eggs. When they
hatch, they will mate with other wasps inside the fig. She
observes the several other females have already laid eggs here.
Which strategy will maximize her fitness (number of
descendants)? Correct Answers Lay more male eggs than any
of the previous females, and then as many female eggs as
possible.
Because increased fecundity means increased fitness, we might
expect to observe the evolution of ever-increasing fecundity, but
this is not the case. Which reason(s) for limits to fecundity do
biologists consider plausible? Correct Answers There are trade-
offs between fecundity and traits linked to survival.
Brown bears in Idaho are smaller, and have lighter fur, than
brown bears living farther north, in Alaska. Which of these
observations would be evidence that these differences in
coloration and body size are the result of local adaptation, rather
than genetic drift and isolation by distance? Correct Answers -
The bears' coloration and body size change gradually from Idaho
to Alaska, and parallel differences in the average annual
temperature along this cline.
-FST between the Idaho and Alaska bear populations is
relatively low (0.1) at most loci across the genome, but it is
much higher (0.65) at a gene responsible for fur coloration.
, -Cubs of Alaska bears bred in captivity and introduced into the
wild in Idaho do not thrive, but do well if they are introduced
into the wild in Alaska, instead.
Classify each of these isolating barriers as prezygotic or
postzygotic. Correct Answers -Two different species of beetles
live and feed on different host plants, and rarely interact.
Prezygotic
-Two different species of birds make different calls to attract
mates, and are not attracted to each other's calls. Prezygotic
-One species of sunflower is adapted to hillsides and another is
adapted to marshes, and hybrids between these species do poorly
in either habitat.
Postzygotic
-Horses and donkeys can mate and produce offspring, but their
offspring are sterile.
Postzygotic
-Two different species of wildflower flower and attract
pollinators at different times of year, and so never exchange
pollen.
Prezygotic
-Two species of ducks can mate and produce eggs, but the
hybrid eggs never hatch.
Postzygotic
Solutions
A female fig wasp arrives at a fig to lay her eggs. When they
hatch, they will mate with other wasps inside the fig. She
observes the several other females have already laid eggs here.
Which strategy will maximize her fitness (number of
descendants)? Correct Answers Lay more male eggs than any
of the previous females, and then as many female eggs as
possible.
Because increased fecundity means increased fitness, we might
expect to observe the evolution of ever-increasing fecundity, but
this is not the case. Which reason(s) for limits to fecundity do
biologists consider plausible? Correct Answers There are trade-
offs between fecundity and traits linked to survival.
Brown bears in Idaho are smaller, and have lighter fur, than
brown bears living farther north, in Alaska. Which of these
observations would be evidence that these differences in
coloration and body size are the result of local adaptation, rather
than genetic drift and isolation by distance? Correct Answers -
The bears' coloration and body size change gradually from Idaho
to Alaska, and parallel differences in the average annual
temperature along this cline.
-FST between the Idaho and Alaska bear populations is
relatively low (0.1) at most loci across the genome, but it is
much higher (0.65) at a gene responsible for fur coloration.
, -Cubs of Alaska bears bred in captivity and introduced into the
wild in Idaho do not thrive, but do well if they are introduced
into the wild in Alaska, instead.
Classify each of these isolating barriers as prezygotic or
postzygotic. Correct Answers -Two different species of beetles
live and feed on different host plants, and rarely interact.
Prezygotic
-Two different species of birds make different calls to attract
mates, and are not attracted to each other's calls. Prezygotic
-One species of sunflower is adapted to hillsides and another is
adapted to marshes, and hybrids between these species do poorly
in either habitat.
Postzygotic
-Horses and donkeys can mate and produce offspring, but their
offspring are sterile.
Postzygotic
-Two different species of wildflower flower and attract
pollinators at different times of year, and so never exchange
pollen.
Prezygotic
-Two species of ducks can mate and produce eggs, but the
hybrid eggs never hatch.
Postzygotic
