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 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
If the low number of hybrid flies in the hybrid zone, relative to the number of D. santomea flies there, is due to the fact that hybrids are poorly adapted to conditions in the hybrid zone, and if fewer hybrid flies are produced with the passage of time, these conditions will most likely lead to
A) fusion.B) reinforcement.
C) stability.
D) further speciation events.
Answer: B
Which two of the following have operated to increase divergence between mosquitofish populations on Andros?
1. improved gene flow2. bottleneck effect
3. sexual selection
4. founder effect
5. natural selection
A) 1 and 3
B) 2 and 3
C) 2 and 4
D) 3 and 4
E) 3 and 5
Answer: E
Which type of reproductive isolation operates to keep the mosquitofish isolated, even when fish from different ponds are reunited in the same body of water? A) behavioral isolation
B) habitat isolationC) temporal isolation
D) mechanical isolation
E) gametic isolation
Answer: A
What is the best way to promote fusion between two related populations of mosquitofish, one of which lives in a predator-rich pond, and the other of which lives in a predator-poor pond? A) Build a canal linking the two ponds that permits free movement of mosquitofish, but not of predators.
B) Transfer only female mosquitofish from a predator-rich pond to a predator-poor pond.C) Perform a reciprocal transfer of females between predator-rich and predator-poor ponds.
D) Remove predators from a predator-rich pond and transfer them to a predator-poor pond.
Answer: A
If one builds a canal linking a predator-rich pond to a predator-poor pond, then what type(s) of selection should subsequently be most expected among the mosquitofish in the original predator-rich pond, and what type(s) should be most expected among the mosquitofish in the formerly predator-poor pond? A) stabilizing selection; directional selection
B) stabilizing selection; stabilizing selectionC) less-intense directional selection; more-intense directional selection
D) less-intense disruptive selection; more-intense disruptive selection
Answer: C
The predatory fish rely on visual cues and speed to capture mosquitofish. Mosquitofish rely on speed and visual cues to avoid the predatory fish. Which adaptation(s) might help the predators survive in ponds that are home to faster mosquitofish?
1. directional selection for increased speed2. stabilizing selection for speed that matches that of the mosquitofish
3. change in hunting behavior that replaces reliance on visual cues with reliance on tactile cues, which can be used to hunt at night
4. change in hunting behavior that eliminates speed in favor of better camouflage, which permits an ambush strategy
A) 1 only
B) 2 only
C) either 1 or 3
D) either 2 or 3
E) 1, 3, or 4
Answer: E
Learn More :
Biology
- One explanation for the evolution of insect wings suggests that wings began as lateral extensions of the body that were used as heat dissipaters for thermoregulation. When they had become sufficiently large, these extensions became useful for gliding through the air, and selection later refined them as flight-producing wings. If this hypothesis is correct, modern insect wings could best be described as
- The existence of the phenomenon of exaptation is most closely associated with which of the following observations that natural selection cannot fashion perfect organisms?
- How many of the following statements concerning the loss of hind limbs during whale evolution are true? 1. It is well documented by a series of transitional fossils. 2. It explains why modern whales have vestigial pelvic girdles. 3. It involved changes in the sequence or expression of Hox genes. 4. It is an example of macroevolution. 5. It, and the loss of limbs by snakes, are an example of similar adaptations to a similar environment.
- Larval flies (maggots) express the Ubx gene in all of their segments, and thereby lack appendages. If this same gene continued to be expressed throughout subsequent developmental stages, except in the head region, and if the result was a fit, sexually mature organism that still strongly resembled a maggot, this would be an example of
- The loss of ventral spines by modern freshwater sticklebacks is due to natural selection operating on the phenotypic effects of Pitx1 gene
- Bagworm moth caterpillars feed on evergreens and carry a silken case or bag around with them in which they eventually pupate. Adult female bagworm moths are larval in appearance; they lack the wings and other structures of the adult male and instead retain the appearance of a caterpillar even though they are sexually mature and can lay eggs within the bag. This is a good example of
- An organism has a relatively large number of Hox genes in its genome. Which of the following is true of this organism?
- On the basis of their morphologies, how might Linnaeus have classified the Hawaiian silverswords?
- The major evolutionary episode corresponding most closely in time with the formation of Pangaea was the
- If two continents converge and are united, then the collision should cause
- The first terrestrial organisms probably were considered which of the following? 1. burrowers 2. photosynthetic 3. multicellular 4. prokaryotes 5. eukaryotes 6. plants and their associated fungi
- Which of the following characteristics should have been possessed by the first animals to colonize land? 1. were probably herbivores (ate photosynthesizers) 2. had four appendages 3. had the ability to resist dehydration 4. had lobe-finned fishes as ancestors 5. were invertebrates
- The snowball Earth hypothesis provides a possible explanation for the
- Which event is nearest in time to the end of the period known as snowball Earth?
- Which of these observations gives the most support to the endosymbiotic theory for the origin of eukaryotic cells?
- Recent evidence indicates that the first major diversification of multicellular eukaryotes may have coincided in time with the
- If it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.2-billion-year-old stromatolites, then one should be surprised to observe evidence of which of the following within such microfossils? I. double-stranded DNA II. a nuclear envelope III. a nucleoid IV. a nucleolus V. ribosomes
- What is thought to be the correct sequence of these events, from earliest to most recent, in the evolution of life on Earth? 1. origin of mitochondria 2. origin of multicellular eukaryotes 3. origin of chloroplasts 4. origin of cyanobacteria 5. origin of fungal-plant symbioses
- What is true of the Cambrian explosion?
- Which of the following statements provides the strongest evidence that prokaryotes evolved before eukaryotes?
- An early consequence of the release of oxygen gas by plant and bacterial photosynthesis was to
- If a fossil is encased in a stratum of sedimentary rock without any strata of igneous rock (for example, lava, volcanic ash) nearby, then it should be
- What is true of the fossil record of mammalian origins?
- Approximately how far back in time does the fossil record extend?
- Which measurement(s) would help determine absolute dates by radiometric means?
If the answers is incorrect or not given, you can answer the above question in the comment box. If the answers is incorrect or not given, you can answer the above question in the comment box.