Question

Many songbirds breed in North America in the spring and summer and then migrate to Central and South America in the fall. They spend the winter in these warmer areas, where they feed and prepare for the spring migration north and another breeding season. Two hypothetical species of sparrow, A and B, overwinter together in mixed flocks in Costa Rica. In spring, species A goes to the east coast of North America, and species B goes to the west coast. What can you say about the isolating mechanisms of these two species? Select one: a. The winter habitat is much more hospitable than the summer habitat, so isolation occurs only in the summer. b. They must have strong postzygotic isolating mechanisms to spend winter in such close proximity. c. Behavioral isolation is preventing any breeding between the two species. d. Their winter habitat has no bearing on their degree of reproductive isolation. e. They must have strong prezygotic isolating mechanisms to spend winter in such close proximity. Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. Pollen grains (which contain sperm cells) from one of the species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species. This situation is an example of _ speciation due to _ reproductive isolation. Select one: a. Sympatric; behavioral b. Sympatric; postzygotic c. Allopatric; postzygotic d. Allopatric; prezygotic e. Sympatric; prezygotic

Many songbirds breed in North America in the spring and summer and then migrate to Central and South America in the fall. They spend the winter in these warmer areas, where they feed and prepare for the spring migration north and another breeding season. Two hypothetical species of sparrow, A and B, overwinter together in mixed flocks in Costa Rica. In spring, species A goes to the east coast of North America, and species B goes to the west coast. What can you say about the isolating mechanisms of these two species?

Select one:
a. The winter habitat is much more hospitable than the summer habitat, so isolation occurs only in the summer.
b. They must have strong postzygotic isolating mechanisms to spend winter in such close proximity.
c. Behavioral isolation is preventing any breeding between the two species.
d. Their winter habitat has no bearing on their degree of reproductive isolation.
e. They must have strong prezygotic isolating mechanisms to spend winter in such close proximity.

Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. Pollen grains (which contain sperm cells) from one of the species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species.
This situation is an example of _________ speciation due to _________ reproductive isolation.

Select one:
a. Sympatric; behavioral
b. Sympatric; postzygotic
c. Allopatric; postzygotic
d. Allopatric; prezygotic
e. Sympatric; prezygotic

Many songbirds breed in North America in the spring and summer and then migrate to Central and South America in the fall. They spend the winter in these warmer areas, where they feed and prepare for the spring migration north and another breeding season. Two hypothetical species of sparrow, A and B, overwinter together in mixed flocks in Costa Rica. In spring, species A goes to the east coast of North America, and species B goes to the west coast. What can you say about the isolating mechanisms of these two species?

Select one:
a. The winter habitat is much more hospitable than the summer habitat, so isolation occurs only in the summer.
b. They must have strong postzygotic isolating mechanisms to spend winter in such close proximity.
c. Behavioral isolation is preventing any breeding between the two species.
d. Their winter habitat has no bearing on their degree of reproductive isolation.
e. They must have strong prezygotic isolating mechanisms to spend winter in such close proximity.

Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. Pollen grains (which contain sperm cells) from one of the species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species.
This situation is an example of speciation due to reproductive isolation.

Select one:
a. Sympatric; behavioral
b. Sympatric; postzygotic
c. Allopatric; postzygotic
d. Allopatric; prezygotic
e. Sympatric; prezygotic

Added by Jennifer W.

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