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There are substantial populations of lions in Africa and Asia.Despite being known as “the king of the jungle,” the African lion is principally found on open savannas,with smaller numbers in woodland areas.Since the 1960s,the ecology of lions has been intensively studied in the Serengeti National Park of Tanzania in East Africa.Lions live in family groups known as prides.Both woodlands and plains prides of the Serengeti are typically composed of six related females,their cubs,and a few unrelated males who mate with the adult females.The females do most of the hunting for the pride,and they must hunt in groups to be successful.Most of the daily activity of males concerns maintenance of territory.Packer et al.have completed a detailed analysis of long-term records of lion populations in a 2000-km² area of the Serengeti National Park.As they report on page 390 of this issue,lion population size has remained remarkably stable for long periods (10 to 20 years) punctuated by sudden increases that do not seem to reflect numbers of available prey.

The population dynamics (changes in the population size) of animals obey several key rules.Population increases are due to births of new individuals and arrival of immigrants from nearby populations,whereas any decreases are due to individuals dying or leaving their natal population.Often births and deaths are dependent on each other either directly or with an intervening time lag.Population increases also depend on the amount of resources that mature females are able to monopolize.However,Packer et al.now reveal an unusual feature of the population dynamics of Serengeti lions.They discovered that lion numbers,both in the woodlands and on the plains,undergo long periods of stability interrupted by abrupt changes.This is intriguing because no such salutatory changes in population dynamics are reported for lion prey such as wildebeest,Cape buffalo,and gazelle.Rather,the populations of these Serengeti prey species have changed without evidence of the dramatic leaps characterizing lion populations since the 1960s,when quantitative censuses began.

A straightforward expectation of predator-prey population dynamics is that a gradual change in resources (prey) would support a corresponding smooth change in predator population size.However,in Serengeti lions,the population increases have been abrupt often constituting an increase of 20 to 50% of the extant population size.The population records since the end of the 1960s include three salutatory changes (1973,1983,and 1999) for lions inhabiting Serengeti woodlands and one (1997) for lions inhabiting the plains.In between these leaps,the lion population remained stable,hovering around the number reached during the previous increase.

Packer and his research team now provide an explanation for these jerky dynamics by incorporating into their simulation model the social grouping behavior of lions within their prides.Serengeti lion prides have an optimal size: In the smallest prides,females have very low reproductive success,because hunting of their major ungulate prey calls for the cooperation of several individuals.In contrast,in the largest prides,females suffer from intense competition for the prey they have subdued jointly.When resources increase sufficiently to support more offspring and when the size of an extant pride is sufficiently large,the pride splits; several related females disperse together to form a new pride.Packer et al.suggest that it is optimal from an evolutionarily standpoint for a group of females to leave their pride and to establish a new pride with a different territory because this behavior ensures greater breeding potential.In this way,a gradual increase in prey population size supports a sequence of continued stability interrupted by abrupt increases in the abundance of lion populations.

The only major decrease (since the 1960s) in the population size of Serengeti lions occurred in 1994.The rapid decline (to 50% of the pre-1994 level) of woodland lions coincided with a decrease in the numbers of wildebeest and Cape buffalo due to a severe drought in that habitat.It is tempting to suggest that the collapse in lion numbers represented a reversal of the social mechanisms that result in punctuated increases in lion population size.A decrease in resources could have affected lion population size by reducing the number of prides in the overall population.However,this possibility cannot be verified because the 1994 decline in lion numbers was in fact due to an epidemic of canine distemper.

It is worth contrasting the population dynamics of Serengeti lions with the known dynamics of other species where long-term data are available.Whereas Serengeti lion population dynamics show salutatory changes in size,all other known predator-prey populations follow—with a time lag—a model in which smooth increases in prey availability result in smooth increases in predator population size.The best documented predator-prey populations display characteristic periodic fluctuations that obey the standard models found in any population ecology textbook.One feature shared by traditional predator-prey models and the Serengeti lion model of Packer et al.is the presence of a time lag between changes in the population size of prey and that of predator.

The new data about Serengeti lion population dynamics enriches our existing palette of predator-prey population patterns.One recent theory takes as a starting point the idea that individual behavior eventually has repercussions on long-term population ecology.The findings of Packer and colleagues support this view,although traditional population theories have yet to incorporate the notion of social behavior into their models.The population dynamics of woodland and plains Serengeti lions are largely driven by the social structure of prides: To breed successfully,lionesses must belong to a pride that is sufficiently large (but not too large).Once a pride exceeds the optimal size,it splits with several females leaving to form a new pride.This leads to an increase in the lion population,presuming that sufficient resources are available to support the increase in offspring.We anticipate that behavior-based population models examining social behavior within populations and how these behaviors influence population growth will ultimately find their way into the analytical toolbox of population ecologists.The use of such models will help ecologists to better understand the dynamics of focal animal populations,and to provide more sophisticated management of threatened animal populations such as those of the Serengeti.(1,077 words)

savanna (also savannah)　n.（尤指非洲的）稀树草原

punctuate　v.不时打断

monopolize　v.独占；垄断

intriguing　adj.非常有趣的；引人入胜的；神秘的

salutatory　adj.跳跃的

wildebeest　n.牛羚（产于非洲）

Cape buffalo　n.产于南非之黑色大水牛

ungulate　adj.蹄状的；有蹄的；有蹄类哺乳动物的

canine distemper　n.犬瘟热

fluctuation　n.起伏；波动

repercussion　n.影响；反响

Serengeti National Park of Tanzania：坦桑尼亚塞伦盖蒂国家公园。1951年建成，1959年得到扩大，同年列入世界遗产名录。

1.【原文】Despite being known as “the king of the jungle,” the African lion is principally found on open savannas,with smaller numbers in woodland areas.

【译文】尽管被尊为“丛林之王”，但人们发现非洲狮主要活动于开阔的稀树草原上，只有少量生存于林地中。

【解析】原文为被动句，其字面意思为“……非洲狮被发现主要存在于……”。但在汉语中，一般很少使用被动句而更多地使用主动句。因此，我们在翻译时一般将其译为主动式，并且添加一个第三人称“人们”作主语。

2.【原文】Lions live in family groups known as prides.

【译文】狮子以家族的形式生活在一起，这种家族被称为狮群。

【解析】“known as prides”在原文中是作为定语来修饰“family groups”。但在翻译时，因为“family groups”被译作了状语“以家族的形式”，“known as prides”就很难译为对应的定语了。因此，我们将其拆开，单独另起一句来译。

3.【原文】lion population size has remained remarkably stable for long periods (10 to 20 years) punctuated by sudden increases that do not seem to reflect numbers of available prey.

【译文】狮子种群规模一直相对稳定，尽管有时数量突然增加，但似乎也反映不出可捕食猎物数量的变化。

【解析】原文为一个结构较复杂的长句，“punctuated by sudden increases”作为一个后置定语，同时，其后又引导了一个定语从句。环环相扣的结构也给翻译造成了困难。一方面，汉语中大多使用短句；另一方面，原文的定语以及定语从句也很难翻译为汉语的相应成分。因此，我们将原文拆译为三个短句，通过动词的连用来解决这一难题。

4.【原文】Often births and deaths are dependent on each other either directly or with an intervening time lag.

【译文】通常出生和死亡或直接或滞后一段时间后显现出彼此间的相互影响。

【解析】原文有两个状语，“directly”和“with an intervening time lag”。前者很好翻译，用“直接相关”表达就可以；而后者与“dependent on each other”则较难搭配。因此我们需要将“dependent on each other”的意思进行引申，译为“显现影响”就比较恰当了。

5.【原文】This is intriguing because no such salutatory changes in population dynamics are reported for lion prey such as wildebeest,Cape buffalo,and gazelle.

【译文】这很奇妙，因为在关于诸如牛羚，非洲水牛和羚羊等狮子猎物的报告中，没有这样的跳跃式动态种群数量的变化。

【解析】原文为被动句，直译的话就是“这样的跳跃式动态种群数量的变化没有被报告……”。但很显然，这样的语序是不符合汉语的表达习惯的。因此，我们将其译为我们汉语较习惯的主动句；同时进行一个小小的词类转换，将原文的动词“report”转译为汉语的名词“报告”。

6.【原文】Rather,the populations of these Serengeti prey species have changed without evidence of the dramatic leaps characterizing lion populations since the 1960s,when quantitative censuses began.

【译文】更确切地说，自从上个世纪60年代开始对狮子种群定量普查以来，没有证据表明狮子种群的数量会随着其猎物种群数量的变化而发生跃进式增长。

【解析】此句的翻译进行了句子成分的调整：原文中主句为“the populations of these Serengeti prey species have changed”，而后面的“without evidence of the dramatic leaps characterizing lion populations”则充当状语成分。但在翻译时我们将状语成分译作了主语“没有证据表明塞伦盖蒂狮子种群的数量发生跃进式增长”，而将原来的主语译作了状语“随着其猎物种群数量的变化”。

7.【原文】However,in Serengeti lions,the population increases have been abrupt often constituting an increase of 20 to 50% of the extant population size.

【译文】然而，塞伦盖蒂狮群数量的增加却具有突发性，经常会出现比现存种群数量多达20%至50%的增幅。

【解析】此处，“constitute”原意为“组成；构成”，但与后面的“增长”难以搭配。因此，我们将其译为“出现”。

8.【原文】Packer and his research team now provide an explanation for these jerky dynamics by incorporating into their simulation model the social grouping behavior of lions within their prides.

【译文】派克和他的研究团队现在运用他们的仿真模式对此提出的解释是：狮群内狮子的社会组织行为导致了这种时而忽然增长的动态变化。

【解析】此句的翻译主要进行的是语序的调整：原句的句子结构十分清晰，我们也可以将其直接译为对应的汉语；但在翻译的过程中，我们需要进行语序的调整，使其符合汉语的表达习惯。

9.【原文】In the smallest prides,females have very low reproductive success.

【译文】在最小的狮群中，雌狮繁殖的成功率很低。

【解析】此句进行的是句子成分的调整：原句中“females”本是主语，在译文中充当定语；“reproductive success”在原文中充当的是宾语成分，在翻译过程中被译为主语；“low”本是定语，在译文中充当的是谓语。

10.【原文】Packer et al.suggest that it is optimal from an evolutionarily standpoint for a group of females to leave their pride and to establish a new pride with a different territory because this behavior ensures greater breeding potential.

【译文】派克等人认为从进化的角度看，一群雌狮离开狮群去到不同的领地建立新的狮群是最佳的选择。因为这种行为保证了更多的哺育机会。

【解析】“suggest”有“建议；提出；暗示”等意思，此处我们将其译为“认为”，从而使语句更加通顺。同时，将后面的状语“from an evolutionarily standpoint”的翻译提前放在句首，更加符合汉语的表达习惯。

11.【原文】The rapid decline (to 50% of the pre-1994 level) of woodland lions coincided with a decrease in the numbers of wildebeest and Cape buffalo due to a severe drought in that habitat.

【译文】林地狮子数量的迅速减少（减少到了1994年前数量水平的50%）恰巧发生在该栖居地由于严重干旱导致牛羚和非洲水牛数量减少的时候。

【解析】此处翻译的重点在于对词组“coincided with”的处理。该词组的意思为“与……一致；与……相符”。因为后面的宾语相对较长，且在逻辑关系上也较难处理，所以我们将其译为“恰巧发生在……的时候”。这样翻译起来就比较通顺了。

12.【原文】It is worth contrasting the population dynamics of Serengeti lions with the known dynamics of other species where long-term data are available.Whereas Serengeti lion population dynamics show salutatory changes in size,all other known predator-prey populations follow—with a time lag—a model in which smooth increases in prey availability result in smooth increases in predator population size.

【译文】尽管塞伦盖蒂狮子种群数量的动态变化体现在规模的跳跃式改变上，而其他所有已知的捕食者与猎物的种群模式却是可捕食猎物的逐渐增加导致捕食者种群规模的逐渐扩大，并且这两个改变之间伴有时间间隔。因此将塞伦盖蒂狮子数量的动态变化与其他有长期数据记录的物种的已知动态变化进行对比是十分有价值的。

【解析】这里主要是根据逻辑关系进行两个句子顺序的调整。原文中前句表转折的结果，而后句表让步的条件。直接按原文语序翻译是不符合汉语的表达习惯的。一般来说，汉语中让步条件在前，转折结果在后。

13.【原文】The best documented predator-prey populations display characteristic periodic fluctuations that obey the standard models found in any population ecology textbook.

【译文】保存有良好记载的捕食者与猎物种群会定期出现其特有的数量波动，这种波动符合种群生态学书上的标准模式。

【解析】原句中有一个定语从句，若直接翻译为定语则显得过长，因此我们就将其拆开，另起一句来译。

14.【原文】One recent theory takes as a starting point the idea that individual behavior eventually has repercussions on long-term population ecology.

【译文】一项最新的理论则以个体行为最终会对整个种群的长期生态产生影响为切入点。

【解析】原文中，“individual behavior eventually has repercussions on long-term population ecology”作为宾语出现，先行词为“idea”。直接翻译宾语就会显得冗长。因此我们将“idea”进行词类转换，译为汉语的动词“认为”，这样后面的宾语从句的翻译就比较简单了；同时原文的主句也不得不拆开，另起一句。

15.【原文】We anticipate that behavior-based population models examining social behavior within populations and how these behaviors influence population growth will ultimately find their way into the analytical toolbox of population ecologists.

【译文】我们预测种群生态学家在选择分析工具时会最终选择以行为为基础的种群模式，用这种模式研究种群内社会行为以及这些行为对种群发展的影响。

【解析】原文中，“examining social behavior within populations and how these behaviors influence population growth”作为后置定语来修饰“models”，直接翻译难度较大。因此我们只能采用拆译法，将主语单独拿出译作一个句子，其余的就好处理了。

在非洲和亚洲，狮子的种群繁多。尽管被尊为“丛林之王”，但人们发现非洲狮主要活动于开阔的稀树草原上，只有少量生存于林地中。自二十世纪六十年代以来，东非坦桑尼亚塞伦盖蒂国家公园对狮子的生态进行了细致的研究。狮子以家族的形式生活在一起，这种家族被称为狮群。在塞伦盖蒂的林地和平原上，狮群通常由六头有血缘关系的雌狮、它们的幼仔、以及几头与成年雌狮交配但与其没有血缘关系的雄狮组成。雌狮负责狮群的大部分捕猎任务，为了成功，它们必须集体捕食。而雄狮每日的活动主要是看护领地。派克等人完成了一份对塞伦盖蒂国家公园方圆2 000公里内狮子数量长期记录的详细分析。在此报告第390页，他们指出，很长一段时间里（10至20年）狮子种群规模一直相对稳定，尽管有时数量突然增加，但似乎也反映不出可捕食猎物数量的变化。

动物数量的动态变化（种群规模的改变）遵循几个主要的规律。种群数量的增加是因为新个体的出生和附近种群的新来移民；而数量的减少则是由于个体的死亡或个体离开自己出生的种群。通常出生和死亡或直接或滞后一段时间后显现出彼此间的相互影响。种群数量的增加还取决于成年雌性动物能够占有的资源数量。然而，派克等人也发现了塞伦盖蒂狮子种群数量动态变化的一个奇异特征。他们发现，狮子的数量，无论是在林地还是在平原上，都在保持了长时间的稳定后被突然的变化打断。这很奇妙，因为在关于诸如牛羚、非洲水牛和羚羊等狮子猎物的报告中，没有这样的跳跃式动态种群数量的变化。更确切地说，自从上个世纪60年代开始对狮子种群定量普查以来，没有证据表明狮子种群的数量会随着其猎物种群数量的变化而发生跃进式增长。

关于捕食者与猎物数量动态变化的简单设想是食物资源（猎物）的逐渐变化会带来捕食者种群数量相应的逐渐变化。然而，塞伦盖蒂狮群数量的增加却具有突发性，经常会出现比现存种群数量多达20%至50%的增幅。二十世纪60年代末以来的狮群数量记录记载了居住在塞伦盖蒂林地中狮群数量的三次跳跃式增加（1973，1983与1999年）以及居住在平原上的狮群数量的一次跳跃式增加（1997年）。在这些跳跃式增加中间的年份，狮群数量保持稳定，徘徊在以前增加后所达到的数量上。

派克和他的研究团队现在运用他们的仿真模式对此提出的解释是：狮群内狮子的社会组织行为导致了这种时而忽然增长的动态变化。塞伦盖蒂狮群有一个优化了的规模：在最小的狮群中，雌狮繁殖的成功率很低，因为猎获它们主要的蹄类猎物需要几个雌狮的协作。相反，在最大的狮群中，雌狮们为获得集体捕获的猎物而激烈竞争。当食物资源足以养活更多的后代，或者现有的狮群过于庞大时，这个狮群就会分开；几个有血缘的雌狮集体离开，建立新的狮群。派克等人认为从进化的角度看，一群雌狮离开狮群去到不同的领地并建立新的狮群是最佳的选择。因为这种行为保证了更多的哺育机会。通过这种方式，猎物种群规模的逐渐增长在使狮群规模保持持续稳定的同时，间以狮子种群数量的急剧增加。

塞伦盖蒂狮群数量唯一一次显著的减少（自20世纪60年代以来）发生在1994年。林地狮子数量的迅速减少（减少到了1994年前数量水平的50%）恰巧发生在该栖居地由于严重干旱导致牛羚和非洲水牛数量减少的时候。这很容易让人联想到这次狮子数量的减少是和上述导致狮群规模不定期增加的社会机制背道而驰的。食物资源的减少会导致所有狮群中的狮子数量的减少，从而影响狮子种群的规模。然而，这种可能性无法被证实。因为1994年狮子数量的减少实际上是因为一场犬瘟热的流行。

尽管塞伦盖蒂狮子种群数量的动态变化体现在规模的跳跃式改变上，而其他所有已知的捕食者与猎物的种群模式却是可捕食猎物的逐渐增加导致捕食者种群规模的逐渐扩大，并且这两个改变之间伴有时间间隔。因此将塞伦盖蒂狮子数量的动态变化与其他有长期数据记录的物种的已知动态变化进行对比是十分有价值的。保存有良好记载的捕食者与猎物种群会定期出现其特有的数量波动，这种波动符合种群生态学书上的标准模式。而传统的捕食者与猎物模式与派克等人研究的塞伦盖蒂狮子种群模式所共有的一个特点是猎物种群规模的改变与捕食者种群规模的改变之间存在间歇期。

关于塞伦盖蒂狮子种群数量动态变化的新数据丰富了我们现有的捕食者与猎物种群关系模式。一项最新的理论则以个体行为最终会对整个种群的长期生态产生影响为切入点。尽管传统的种群理论还需要将社会行为理论纳入其模式中，派克与其同事们的发现却为这一新的理论提供了依据。塞伦盖蒂林地与平原上的狮子种群数量的动态变化很大程度上受狮群社会结构的影响：为了成功繁育，雌狮必须归附于一个足够大的狮群中（但也不能太大）。一旦狮群的数量超过了最优规模，就会有几只雌狮离开，去建立新的狮群。假如有充足的食物资源来养活所增加的后代，这就会导致狮子数量的增加。我们预测种群生态学家在选择分析工具时会最终选择以行为为基础的种群模式，用这种模式研究种群内社会行为以及这些行为对种群发展的影响。此模式的使用将帮助生态学家更好地理解一些人类重点关注的动物种群的动态变化，并能为诸如塞伦盖蒂的狮子等濒危动物种群提供更加精细的管理模式。