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1、小编给你一个美联英语官方免费试听课申请链接：美联英语提供：托福英语 托福阅读 热带蜂群的分布托福阅读原文【1】In 1977 ecologists Stephen Hubbell and Leslie Johnson recorded a dramatic example of how social interactions can produce and enforce regular spacing in a population. They studied competition and nest spacing in populations of stingless bees in t
2、ropical dry forests in Costa Rica. Though these bees do no sting, rival colonies of some species fight fiercely over potential nesting sites.Stingless bees are abundant in tropical and subtropical environments, where they gather nectar and pollen from a wide variety of flowers. They generally nest i
3、n trees and live in colonies made up of hundreds to thousands of workers. Hubbell and Johnson observed that some species of stingless bees are highly aggressive to members of their species from other colonies, while other species are not. Aggressive species usually forage in groups and feed mainly o
4、n flowers that occur in high-density clumps. Nonaggressive species feed singly or in small groups and on more widely distributed flowers.【2】Hubbell and Johnson studied several species of stingless bees to determine whether there is a relationship between aggressiveness and patterns of colony distrib
5、ution. They predicted that the colonies of aggressive species would show regular distributions, while those of nonaggressive species would show random or closely grouped (clumped) distribution. They concentrated their studies on a thirteen-hectare tract of tropical dry forest that contained numerous
6、 nests of nine species of stingless bees.【3】Though Hubbell and Johnson were interested in how bee behavior might affect colony distributions, they recognized that the availability of potential nest sites for colonies could also affect distributions. So as one of the first steps in their study, they
7、mapped the distributions of trees suitable for nesting. They found that potential nest trees were distributed randomly through the study area. They also found that the number of potential nest sites was much greater than the number of bee colonies. What did these measurements show the researchers? T
8、he number of colonies in the study area was not limited by availability of suitable trees, and a clumped or regular distribution of colonies was not due to an underlying clumped or regular distribution of potential nest sites.【4】Hubbell and Johnson mapped the nests of five of the nine species of sti
9、ngless bees accurately, and the nests of four of these species were distributed regularly. All four species with regular nest distributions were highly aggressive to bees from other colonies of their own species. The fifth species was not aggressive, and its nests were randomly distributed over the
10、study area.【5】The researchers also studied the process by which the aggressive species establish new colonies. Their observations provide insights into the mechanisms that establish and maintain the regular nest distribution of these species. Aggressive species apparently mark prospective nest sites
11、 with pheromones, chemical substances secreted by some animals for communication with other members of their species. The pheromone secreted by these stingless bees attracts and aggregates members of their colony to the prospective nest site; however, it also attracts workers from other nests.【6】If
12、workers from two different colonies arrive at the prospective nest at the same time, they may fight for possession. Fights may be escalated into protracted battles. The researchers observed battles over a nest tree that lasted for two weeks. Each dawn, fifteen to thirty workers from two competing co
13、lonies arrived at the contested nest site. The workers from the two colonies faced off in two swarms and displayed and fought with each other. In the displays, pairs of bees faced each other, slowly flew vertically to a height of about three meters, and then grappled each other to the ground. When t
14、he two bees hit the ground, they separated, faced off, and performed another aerial display. Bees did not appear to be injured in these fights, which were apparently ritualized. The two swarms abandoned the battle at about 8 or 9 a.m. each morning, only to re-form and begin again the next day just a
15、fter dawn. While this contest over an unoccupied nest site produced no obvious mortality, fights over occupied nestssometimes kill over 1,000 bees in a single battle.【1】1977年，生态学家斯蒂芬胡贝尔（Lesbell Johnson）和莱斯利约翰逊（Leslie Johnson）记录了一个戏剧性的例子，说明社会互动如何产生，并在人口中实施规则间距他们在哥斯达黎加的热带干旱森林中研究了无畏蜜蜂种群的竞争和巢距。虽然这些蜜蜂没有刺
16、痛，但是一些物种的对立殖民地在潜在的筑巢场地上猛烈地战斗。无畏的蜜蜂在热带和亚热带环境中丰富，在那里从各种各样的花朵中收集花蜜和花粉。他们一般在树上筑巢，生活在由数以千计的工人组成的殖民地。胡贝和约翰逊观察到，一些无畏的蜜蜂种类对其他殖民地的物种的成员具有高度的侵蚀性，而其他物种则不具有侵略性。侵略性物种通常在群体中饲料，主要以高密度团块中的花为主。非侵略性物种单独饲养或以小群体和更广泛分布的花卉进食。【2】胡贝尔和约翰逊研究了几种无畏的蜜蜂，以确定侵略性与殖民地分布格局之间是否存在关系。他们预测，侵略性物种的殖民地会显示出正常的分布，而非侵略物种的殖民地将显示随机或紧密分组（聚集）分布。他们将研究集中在一个十三公顷的热带干燥森林中，其中包含了九种无畏蜜蜂的巢。【3】尽管胡贝尔和约翰逊对蜜蜂行为可能如何影响殖民地分布感兴趣，但他们认识到殖民地潜在巢点的可用性也可能影响分布。所以作为他们研究的第一步，他们映射适合嵌套的树的分布。他们发现潜在的巢树随机分布在研究区域。他们还发现，潜在巢点的数量远远大于蜂群的数量。这
