托福阅读真题+题目+答案：Group Foraging

托福阅读真题+题目+答案：Group Foraging

Bluegill sunfish obtain food by flushing (forcing into the open)small aquatic insects from dense vegetation. Researcher Gary Mittelbach hypothesized that larger foraging (food searching)groups might flush out more prey and increase the average number of prey obtained per group member. He examined this hypothesis by experimentally manipulating the foraging group size of bluegill sunfish in a controlled laboratory setting. Mittelbach placed 300 small aquatic prey into a large aquarium containing juvenile bluegill sunfish. He examined the success of bluegills that were foraging alone, in pairs,and in groups (ranging from three to six bluegills). Mittelbach measured the number of prey captured per bluegill, and he found a positive relationship between foraging group size and individual foraging success (the larger the group, the greater the success) up to a group size of four fish.The increased feeding rate per individual was due to two factors.First, more prey were flushed when group size rose. ⬛ Second, prey clumped together, so when one group member found prey, others swam over to this area and then often found food themselves.

1.According to paragraph 1, all of the following are true about Gary Mittelbach's experiments on foraging group size EXCEPT:

O The experimenter controlled the size of foraging groups.

O The experiments were conducted on fish in an aquarium rather than in a natural setting.

O The experiments confirmed Mittelbach's hypothesis.

O The experiments used a total of 300 bluegill sunfish.

2.From the information in paragraph 1, it can be inferred that groups of five foraging bluegill sunfish

O did not have significantly greater foraging success than groups of four foraging fish

O were found to have significantly less foraging success than pairs of foraging fish

O caught different types of prey than fish that foraged alone

O do not occur in natural settings

While increased group size in bluegills does benefit each individual forager in its intake of food (its per capita foraging success), there is no evidence to suggest that bluegill foragers hunt in any coordinated or cooperative fashion. ⬛ The manner in which bluegills increase foraging efficiency in larger groups (that is, by flushing) is only one means of increased foraging efficiency through group living. ⬛ For example, in a number of species, increased group size reduces the amount of time that any given individual needs to devote to antipredator activities-often, but not always, increasing per capita foraging success. ⬛

The general relationship between group size and foraging success uncovered by Mittelbach has been found over and over in animal studies.For example,Scott Creel ran an analysis on foraging success and group size in seven species that hunt in groups.Overall, Creel found a strong positive relationship between per capita foraging success and group size.

3.According to paragraph 3, how did Scott Creel's analysis relate to Mittelbach's experiments?

O It called into question the relationship between group size and foraging success uncovered by Mittelbach.

O It showed that Mittelbach's conclusions were true for some other species in addition to bluegill sunfish.

O Mittelbach used it as the basis upon which he formed his hypothesis.

O It found that the general relationship between group size and foraging success uncovered by Mittelbach held true for only seven species.

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