Question

From the passage it can be inferred that the call pulse rate of male northern elephant seals in the southern rookeries was faster because:

• A. a large number of male northern elephant seals from Año Nuevo Island might have migrated to the southern rookeries to recolonise them.
• B. a large number of male northern elephant seals migrated from the southern rookeries to Año Nuevo Island in the early 1970s
• C. the male northern elephant seals of Isla Guadalupe with faster call pulse rates might have been the original settlers of the southern rookeries.
• D. the calls of male northern elephant seals in the southern rookeries have more sophisticated structures, containing doublets and triplets
• A. The call tempo of individual immigrant male seals changed to match the average tempo of resident male seals in the host colony.
• B. 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.
• C. The call tempo of individual male seals in host colonies changed to match the average call tempo of immigrant male seals.
• D. Besides Isla Guadalupe, there was one more surviving colony with the same average male call tempo from which no migration took place.
• A. The calls have transformed from exhibiting simple composition, great individual variety, and less regional variety to complex composition, less individual variety, and great regional variety.
• B. Owing to migrations in the aftermath of near species extinction, the average call pulse rates in the recolonised breeding locations exhibited a gradual increase until they matched the tempo at the founding colony.
• C. The calls have transformed from exhibiting simple composition, less individual variety, and great regional variety to complex composition, great individual variety, and less regional variety.
• D. Owing to migrations in the aftermath of near species extinction, the calls have transformed from exhibiting complex composition, less individual variety, and great regional variety to simple composition, less individual variety, and great regional variety.
• A. male northern elephant seals might not have exhibited dialects had they not become nearly extinct in the nineteenth century.
• B. the average call pulse rate of male northern elephant seals at Año Nuevo Island increased from the early 1970s till the disappearance of dialects.
• C. 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.
• D. changes in population and migration had no effect on the call pulse rate of individual male northern elephant seals.

Answer 1

The Correct Option is C

The passage describes the diversification of call pulse rates among northern elephant seals at various colonies. It specifically mentions that all existing northern elephant seals are descendants of a small herd from Isla Guadalupe. As this population expanded, differing tempos in male vocal displays were noted in more recently colonized islands. The passage indicates that the average pulse rate changes could be attributed to immigration patterns from faster-paced southern rookeries. It also speculates that the differing tempos were initially due to random selection of founding males at each site. Given this context, the inference can be made: the call pulse rate of male northern elephant seals in the southern rookeries was faster because the male northern elephant seals of Isla Guadalupe with faster call pulse rates might have been the original settlers of the southern rookeries. This hypothesis aligns with the passage's suggestion that different seals with inherently distinct call features happened to settle different locations, leading to the observed variations in call pulse rates. 

Answer 2

The passage explains how the dialects of male northern elephant seal calls have disappeared over time. Initially, these dialects were observed as differences in the tempo of threat calls among seals from different colonies. The variation in tempos was believed to be a result of isolation, as the seals were recolonizing former breeding sites from a small founder colony in Isla Guadalupe. 

The passage discusses a scenario where immigration from other colonies, which had different pulse rates, impacted the tempo of calls. Specifically, at Año Nuevo Island, the call tempo slowly increased due to the influence of immigrant males from southern rookeries with faster pulse rates.

To ensure that these dialects did not disappear, it would have been necessary for the call tempo of immigrant males to align with that of resident males. This would prevent the average tempo at a colony from reverting back to that of the founder colony, thus preserving the dialect differences that had developed over time.

The correct condition is: The call tempo of individual immigrant male seals changed to match the average tempo of resident male seals in the host colony.

This adjustment would have maintained the observed regional dialects by preventing immigrants from altering the local average tempo and contributing to the homogenization of the dialects across different colonies.

Answer 3

The correct answer for the transformation of male northern elephant seal calls is: "The calls have transformed from exhibiting simple composition, less individual variety, and great regional variety to complex composition, great individual variety, and less regional variety." This conclusion can be drawn from the following analysis of the passage:

1. Initially, the calls of northern elephant seals exhibited simple composition, and there was great regional variety as different breeding sites developed distinct dialects owing to isolation.
2. Over time, due to population expansion and immigration, these geographical dialects began to blend, resulting in less regional variety, as the average pulse rates across different locations regressed to match the founding colony's pulse rate.
3. Modern observations indicate that calls now reflect a complex composition, showcasing structural elements such as doublets or triplets, rather than just varying tempos.
4. The passage also highlights that today's male northern elephant seals exhibit greater individual variety compared to earlier times when individual calls were more uniform.

Thus, the evolutionary history of male northern elephant seal calls encompasses a shift from simple and regionally diverse calls to more complex and individually diverse calls with reduced regional variation.

Answer 4

Let's examine each statement individually:
Option A: This inference can be drawn from the second paragraph, where it's mentioned that on recently colonized islands, the tempos of male vocal displays showed stronger differences compared to those from Isla Guadalupe, the founder colony. The passage indirectly attributes the inception of eventual dialects to the dynamic changes resulting from the near extinction of elephant seals. Hence, Option A can be inferred from the passage.
Option B: This inference can be made from the mention of the increase in pulse rate in the early 1970s due to immigration from southern rookeries and the subsequent regression of calls to the average pulse rate of the founder colony as the population continued to expand and receive immigrants. Thus, Option B can be inferred from the passage.
Option C: The passage does not support or make any claim similar to Option C.
Option D: This inference can be drawn from the fourth paragraph, where it's stated that at the individual level, the pulse of the calls remained consistent, indicating that changing variables have minimal effect on the individual vocal signature of the elephant seals. Therefore, Option D can be inferred from the passage.

So, the correct option is (C): 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.