Q. 6: Which one of the following conditions, if true, could have ensured that male northern elephant seal dialects did not disappear?
A. Besides Isla Guadalupe, there was one more surviving colony with the same average male call tempo from which no migration took place.
B. The call tempo of individual male seals in host colonies changed to match the average call tempo of immigrant male seals.
C. Besides Isla Guadalupe, there was one more founder colony with the same average male call tempo from which male seals migrated to various other colonies.
D. The call tempo of individual immigrant male seals changed to match the average tempo of resident male seals in the host colony..
Correct Answer D.
According to the passage, the possible reason for dialects disappearing is that “as the population continued to expand and the islands kept on receiving immigrants from the original population, the calls in all locations would have eventually regressed to the average pulse rate of the founder colony”. If, instead, the call tempo of the immigrant seals changed to match that of the host colony (each of which has a different dialect), then dialects would be different.
Option A is incorrect as it is the immigrant male seals that change the average call tempo. Option B states exactly what happened, resulting in the diappearance of dialects. The scenario in option C would not change the outcome in any way.
Q. 7: All of the following can be inferred from Le Boeuf’s study as described in the passage EXCEPT that:
A. changes in population and migration had no effect on the call pulse rate of individual male northern elephant seals.
B. the influx of new northern elephant seals into Año Nuevo Island would have soon made the call pulse rate of its male seals exceed that of those at Isla Guadalupe.
C. male northern elephant seals might not have exhibited dialects had they not become nearly extinct in the nineteenth century.
D. the average call pulse rate of male northern elephant seals at Año Nuevo Island increased from the early 1970s till the disappearance of dialects.
Correct Answer B.
According to the passage, over time, with migrations, the calls regressed to the average pulse rate of the founder colony in Isla Guadalupe. The passage does not indicate that the influx of new northern elephant seals into Año Nuevo Island would have made the call pulse rate of its male seals exceed that of those at Isla Guadalupe.
All other options can be inferred:
Option A: “At the individual level, the pulse of the calls stayed the same: A male would maintain his vocal signature throughout his lifetime.”
Option C: “This led Le Boeufvand his collaborator, Lewis Petrinovich, to deduce that the dialects were, perhaps, a result of isolation over time, after the breeding sites had been recolonized.”
Option D: “In the decades that followed, scientists noticed that the geographical variations reported in 1969 were not obvious anymore.”
Q. 8: Which one of the following best sums up the overall history of transformation of male northern elephant seal calls?
Correct Answer D.
The last few lines of the passage have the answer: “Modern males exhibit more individual diversity, and their calls are more complex. While 50 years ago the drumming pattern was quite simple and the dialects denoted just a change in tempo, Casey explained, the calls recorded today have more complex structures”.
Q. 9: From the passage it can be inferred that the call pulse rate of male northern elephant seals in the southern rookeries was faster because:
Correct Answer B.
Note the observation in paragraph 4: “At other sites, where the scientists found faster pulse rates, the opposite would have happened—seals with faster rates would have happened to arrive first.”