54 beetle pollinators of a particular plant are

____ 54.
Beetle pollinators of a particular plant are attracted to its flowers' bright orange color.
The beetles not only pollinate the flowers, but they mate while inside of the flowers. A mutant
version of the plant with red flowers becomes more common with the passage of time. A particular
variant of the beetle prefers the red flowers to the orange flowers. Over time, these two beetle
variants diverge from each other to such an extent that interbreeding is no longer possible. What
kind of speciation has occurred in this example, and what has driven it?
a. allopatric speciation, ecological isolation
b. sympatric speciation, habitat differentiation
c. allopatric speciation, behavioral isolation
d. sympatric speciation, sexual selection
e. sympatric speciation, allopolyploidy
____ 55.
A hybrid zone is properly defined as
____ 56.
The most likely explanation for the high rate of sympatric speciation that apparently
existed among the cichlids of Lake Victoria in the past is

The following questions refer to the description below.
On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist.
Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located
about 200 miles away. At higher elevations, and found only on Sao Tomé, is found the very closely
related Drosophila santomea . The two species can hybridize, though male hybrids are sterile. A
hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D.
santomea . Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more
closely related to mainland D. yakuba than to D. santomea (2n=4 in both species). Sao Tomé rose
from the Atlantic Ocean about 14 million years ago.
____ 57.
Which of these evolutionary trees represents the situation described in the paragraph
above (NOTE: yakuba (I) represents the island population, and yakuba (M) represents the mainland
population)?

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