A female fly, full of fertilized eggs, is swept by high winds to an island far out to sea. She is the first fly to arrive on this island, and the only fly to arrive in this way. Thousands of years later, her numerous offspring occupy the island, but none of them resembles her. There are, instead, several species, each of which eats only a certain type of food. None of the species can fly, for their flight wings are absent, and their balancing organs (in other words, halteres) are now used in courtship displays. The male members of each species bear modified halteres that are unique in appearance to their species. Females bear vestigial halteres. The ranges of all of the daughter species overlap.
If these fly species lost the ability to fly independently of each other as a result of separate mutation events in each lineage, then the flightless condition in these species could be an example of A) adaptive radiation.
B) species selection.C) sexual selection.
D) allometric growth.
E) habitat differentiation.
Answer: B
In each fly species, the entire body segment that gave rise to the original flight wings is missing. The mutation(s) that led to the flightless condition could have A) duplicated all of the Hox genes in these flies' genomes.
B) altered the nucleotide sequence within a Hox gene.C) altered the expression of a Hox gene.
D) all three of the above responses
E) two of the above answers are correct
Answer: E
Fly species W, found in a certain part of the island, produces fertile offspring with species Y. Species W does not produce fertile offspring with species X or Z. If no other species can hybridize, then species W and Y
A) have genomes that are still similar enough for successful meiosis to occur in hybrid flies.B) have more genetic similarity with each other than either did with the other two species.
C) may fuse into a single species if their hybrids remain fertile over the course of many generations.
D) Three of the above statements are correct.
E) Two of the statements above are correct.
Answer: D
Which of these fly organs, as they exist in current fly populations, best fits the description of an exaptation?
A) wingsB) balancing organs
C) mouthparts
D) thoraxes
E) walking appendages
Answer: B
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