我不会像其他老师那样, 如果我不告诉你生活很辛苦. I wouldn't be much of teacher, if I didn't tell you that life is tough.
而且世上每个人只为自己着想. and everyone's looking out for themselves in this world.
人就是这样嘛 That's just the way it is, people.
你知道我总是说 生物学 You know how I always say that biology
最终是关于交配 而不是死亡? is ultimately about sex and not dying?
好吧, 这两件事比我们想象的还难 Well, both of those things are more difficult
因为这世上还有个东西叫 竞争 than we'd like them to be, because of competition.
这星球上的资源是有限的, There's a finite amount of resources on this planet,
所以进化驱使我们为资源竞争 这样我们就可以 so evolution drives us to compete for them so that we can
生存足够长的时间来散播我们的基因. survive long enough to spread our genes all over the place.
自然的 当不同物种的栖息地重叠时 它们之间的竞争 And naturally, competition is a really important part of how
也是相互作用的一个重要部分. different species interact when their habitats overlap.
这些物种之间的相互作用 These interactions between species are
定义了一个 群落. what define ecological communities.
群落生态学 研究的是不同物种间的相互作用 So it makes sense that community ecology studies these
不论它们在哪儿, interactions anywhere they take place,
从潮池到整个海洋, 从腐木到整个森林. from a tide pool to the whole ocean, from a rotting log to entire forest.
虽然物种间的相互影响大多都是竞争 But just because inter-species interaction is mostly competitive
但这不意味着群落生态学只关注 doesn't necessarily mean that community ecology is all about big,
血腥的大牙齿和大爪子, 就像电视里的"自然世界"那样. bloody, tooth-and-claw scenes like from cable-TV nature shows.
虽然事实上 群落生态学跟这些血腥的东西有很大关系, 但我们这集不讲那些, 下周再说. Actually, a lot of it is, but we're not going to get there until next week.
现在, 让我们只关注"竞争", 它很普遍 For now, let's just note that competition, while prevalent
很重要, 蛮危险, 还有点麻烦, and important, is also pretty dangerous, kind of a hassle,
还能伤害到别人. and can really hurt.
很多物种的相互作用 实际上回避了 So a lot of inter-species interaction is actually about sidestepping
直接竞争, 而是想尽办法瓜分资源, direct competition and instead finding ways to divvy up resources,
还有一些, 则会和平共处. or otherwise let species just get along.
你能感受到爱吗? Can you feel the love?
小心了伙计! 因为现在我们周围 Careful guys! Because right now we're surrounded potentially
到处都有物种在竞争. lethal interspecific competition going on all over the place.
因为我们是动物 我们通常一想到"竞争" Since we're animals, we usually think of competition as going
就以为是动物之间的竞争, 但实际上它几乎发生在所有生物身上. on between animals, but really it happens between almost all
就以为是动物之间的竞争, 但实际上它几乎发生在所有生物身上. members of the four Kingdoms of life.
每当生物竞争 肯定是在争夺相同的资源 Whenever species compete, they're going after the same resources
它们需要这些资源来生存和繁衍. that they need for their survival and continued population growth.
在这个花园里 杂草在和向日葵 In this garden, the weeds are competing with the sunflower,
玉米 茴香 竞争土壤里的营养物质和水. the corn and the dill for nutrients and water in the soil.
因为这些资源是有限的 So, these resources, because they're finite in this area,
也是我们之前讨论过的"限制因素". are the limiting factors that we've talked about.
生物的数量只能增长到这些因素允许的数量. The population can only get as big as these factors will allow.
这些讨厌的杂草 随着时间推移 Now, a particularly nasty weed could, over time,
能干掉所有蔬菜 eliminate the veggies entirely.
这种竞争叫做"竞争排除" Such elimination is known as competitive exclusion, and
它是群落生态学中最基本的特性. it's one of the most fundamental properties in community ecology,
而且生活 也是这样啊. and also, like, life.
因为事实是 当2个种群竞争相同的资源 Because the fact is, when two species are competing for
其中之一最终会更成功些 the same resources, one of them is eventually
并且干掉另一个种群. going to be more successfuland eliminate the other.
这个残酷的事实叫做 竞争排斥原理 This bitter truth is known as the competitive exclusion principle,
1934 年由俄罗斯生态学家 G.F.高斯 首次发现 and it was first identified in 1934 by Russian ecologist G. F. Gause
他那时在研究两种关系密切的单细胞生物 in a study of two closely-related species of microscopic protists.
他在 22 岁时就出名了 When he was only 22 years old, Gause made a name for himself
因为他做了个让 2 种原生生物竞争的实验 by conducting experiments that pitted one species of protist,
双小核草履虫 对抗 尾草履虫 Paramecium aurelia, against another, Paramecium caudatum.
首先 高斯单独繁育这两个物种 给了它们相同的资源 First, Gause grew each species separately with the exact same
并且发现它们俩都 resources, and found that each developed rapidly
繁育出了稳定的数量 and established stable populations.
但是 当它们一起生活时 But when he grew them in the same container,
尾草履虫很快就被 双小核草履虫灭光了 P. caudatum was soon driven to extinction by P. aurelia.
双小核草履虫有竞争优势是因为 Paramecium aurelia gained a competitive advantage because
它的数量增长速度略快于尾草履虫. its population grew slightly faster than P. caudatum's.
高斯的实验显示 在没有其他干扰的情况下 So Gause's experiment showed that, in the absence of another
需要相同资源的两个物种 disturbance, two species that require the same resources
不能无限期地在同一栖息地生活 cannot live indefinitely in the same habitat.
劣势的竞争者终将被淘汰 The inferior competitor will be eliminated.
有道理 但如果竞争排斥是自然规律 Makes sense. But if competitive exclusion is the natural law
那为什么地球没有变成一个疯狂的竞争马戏团 of the land, then why isn't all of earth just a crazy crap-circus
捕食来捕食去 最后 of constant competition, predation and ultimately,
把所有失败者都灭掉? extinction of all those losers?
有几个原因: 1, 并不是所有资源都有限制. For a couple of reasons: First, not all resources are limiting.
两种鲨鱼也许会在海洋里争水, Two species of sharks may compete for water in the ocean,
但海洋 你知道 它超广阔的 but the ocean is, you know, gigantic.
所以水的因素没有限制到它们的人口增长. So that's not what limits their population growth.
相反, 食物的数量, 比如他俩都会吃的某种鱼, Rather, the amount of food, like a specific fish that they both eat,
可能是有限制的, 而其他资源是丰富的. could be limiting, while other resources are plentiful.
2, 因为几乎每个群落都有超级多的多样性 Second, as the overwhelming diversity of life in almost any
向我们展示了, 大多数物种, 甚至是那些几乎彼此一模一样的物种 community shows us, most species, even ones that are almost
都有足够的适应能力去找到一种方法 identical to each other, are adaptable enough to find a way
在竞争中生存. to survive in the face of competition.
他们通过找 生态位 做到这一点 生态位是那个环境中所有资源的总和 They do this by finding an ecological niche, the sum of all resources,
包括生物的和非生物的, both biotic and abiotic, that a species uses in its environment.
你可以把生物的生态位 想成是他在群落中的工作 You can think of an organism's niche as its job in the community
这工作给它提供了某种生活方式 that provides it with a certain lifestyle.
我们倾向于做那些 我们比别人做的更出色的工作 We tend to keep jobs that we can do better than anyone else
如果我们找不到工作绝望了 in our community, and if we're desperate, we a do a job
我们会做那些别人不想做的工作 that nobody else wants to do.
但不论是什么样的工作 我们都会得到薪水 But no matter what job we have, what it pays
薪水决定了我们的生活方式 in terms of resources dictates our lifestyle.
所以找到一个舒适的生态位 So, finding a nice, comfy niche that you have pretty much
不仅会有稳定的食物收入 to yourself not only provides a steady income of food and other
还避免了竞争排斥 stuff, it also allows a species to avoid competitive exclusion.
而这 反过来 又有助于生态群落变得更稳定 And this, in turn, helps createa more stable ecological community.
这是个优雅又和平的解决方案 It's an elegant and peaceful solution,
我希望我们人类也能想出这样的好方法 I wish we humans could figure out something as good.
但就像生活中的其他东西 这种相对安全 But as with anything in life, this relative security
和稳定性是要付出代价的 and stability comes at a price.
悲剧的是它阻止了其他物种拥有这种生活方式 The bummer is that it prevents some species from living the lifestyle
那些家伙原本可以获得这种生活方式的 如果没人跟它们竞争的话 that they could have if nobody else competed with them at all.
这种理想情况叫做 This ideal situation is called
基本生态位 a fundamental niche, and it's just that, an ideal.
基本生态位就是它可以利用到的资源. Few, if any species ever get to live that way.
因为想避免竞争排斥 Instead, because of the need to avoid competitive exclusion
许多物种选择去干不同的工作 in order to survive, many species end up with
生活方式因此也变化了 a different job, and hence lifestyle.
比如某人不一定得找一份在大学里做研究的工作, It's not necessarily the job that they studied for in college,
但做这份工作会获得体面的生活 这就是所谓的 实际生态位 but it makes a decent living, and that's called a realized niche.
我的朋友, 这就是大自然管理冲突的方法 This, my friends, is how nature does conflict management.
但它听起来有点不自然 不是吗? But it sounds kind of unnatural, doesn't it?
我的意思是 高斯教会我们竞争 I mean, Gause taught us that competition,
和赢得竞争 是自然秩序 and winning the competition, was the natural order of things.
那为什么这个自然秩序 So how can it be that part of the natural order actually
可以让大家都参与竞争 也都能获利共存的呢？ involves letting everyone compete and win just a little bit?
我们是怎么发现 And how did we ever come to discover that things
"竞争"实际上是这样工作的呢? actually worked this way?
好吧 这涉及到了一个特殊的人 Well, it took a special kind of person, and to tell you
为了讲他的故事, 我得去找把特殊的椅子 about him, I'm going to need a special kind of chair.
加拿大出生的生态学家 罗伯特·麦克阿瑟 在他快30岁时 Canadian born ecologist Robert MacArthur was in his late 20's
做了一个重大发现 使他成为了 when he made a discovery that made him one of the most
20世纪最有影响力的生态学家之一 influential ecologists of the 20th century.
那时是1958年 他在耶鲁大学折腾他的博士论文 While researching his doctoral thesis is at Yale University in 1958 ,
他研究的是 在美国东北部针叶林中生活的五种莺. he was studying five species of warblers that live in coniferous
他研究的是 在美国东北部针叶林中生活的五种莺. forests in the northeastern United States.
在当时, 因为有很多种莺生活在一起, At the time, because there were so many different species
它们用于进食和交配的生活空间都靠的很近. of warblers that lived, fed and mated in such close quarters,
许多鸟类学家认为 这些鸟 many ornithologists thought that the birds occupied
占据了完全相同的生态位 the exact same niche and thus, were an exception
它是 高斯竞争排斥原则 的一个例外 to Gause's competitive exclusion principle.
但麦克阿瑟不相信这是个例外 But MacArthur was not convinced.
作为一名受过训练的数学家 他开始着手研究 A mathematician by training, he set out to measure exactly how and
每一种莺到底是如何觅食 筑巢和交配 where each kind of warbler did its foraging, nesting and mating.
为了做到这一点 它把鸟住的树 In order to do this, he studied each tree the birds lived in,
划分成一个个的区 准确的来讲是16个区 dividing them into zones, 16 zones to be exact,
他从树干底部的苔藓 from bare lichen at the base of the trunk,
分到了树顶冒出新芽的树枝 to new needles and buds at the tips of the branches.
在观察多棵树上的多只鸟 很多个几个季节后 After many seasons of observing many birds in many trees,
他发现 每一种莺会在不同的时间 he found that each species of warbler divided its time
去树上不同的部分 differently among the various parts of the tree.
例如 有一种莺 叫栗颊林莺 One warbler, called the Cape May, for example,
他大部分时间都呆在树顶外侧 spent most of its time toward the outside of the tree at the top.
而另一种莺 栗胸林莺 它经常呆在树中间 Meanwhile, the Bay Breasted fed mostly around the middle interior.
麦克阿瑟还发现 每种莺 MacArthur also found that each of the warblers each had
都有不同的狩猎和觅食习惯 different hunting and foraging habits and even bred at
甚至连繁殖时间都稍有不同 slightly different times of the year, so that their highest
所以他们的粮食需求并没有重叠 food requirements didn't overlap.
这些差异说明了莺如何分割 These differences illustrated how the warblers partitioned
其有限的资源 找到它们的实际生态位 their limiting resources, each finding its realized niche
逃避竞争排斥的命运 that allowed it to escape the fate of competitive exclusion.
他观察到的现象 现在被称为 资源分配 The phenomenon he observed is now known as resource partitioning
相似的物种生活在不同的生态位里 从而能够共存 when similar species settle into separate niches that let them coexist.
感谢这一发现 麦克阿瑟后来被称为 Thanks in part to this discovery, MacArthur became known as
现代生态学的先驱者 他鼓励以好奇心 a pioneer of modern ecology, encouraging curiosity
和大胆假设来做研究 还倡导在生态研究中使用遗传学 and hypothesis driven research, championing the use of genetics
并且他还和生物学家合作 in ecological study, and collaborating with biologists like
比如 E.O.威尔逊 和 贾雷德·戴蒙德 E. O. Wilson and Jared Diamond.
可悲的是 他42岁时死于肾癌 Sadly, he died of renal cancer at the age of 42,
但他研究北方莺的事 but his study of northern warblers remains a classic
仍然是今天经典的生态学教学案例 example of community ecology that is still taught today.
如果生物可以做到这一点 如果他们可以 So, if organisms can do this, if they can behave in ways that
最大限度地减少竞争 就会增加了生存的概率 help minimize competition while increasing the odds for survival,
与避免竞争行为相关的特征 it follows that traits associated with this behavior
会被自然选择青睐 would start being selected favorably.
毕竟 这就是自然选择的目的嘛 After all, that's what natural selection is for.
当这种情况发生时 叫做 特征取代 When this happens, it's known as character displacement.
为了演示这种情况 让我们看看其他的著名生态学家 To demonstrate, let's go back to some other, famous ecologists
一对进化生物学夫妇 our favorite couple of evolutionary biologists and love birds,
彼得·格兰特 和 罗斯玛丽·格兰特 Peter and Rosemary Grant.
我们之前讨论过 他们如何观察 I told you before about how they observed the process
加拉帕戈斯群岛上雀类形态的变化过程. of speciation among Darwin's famous Galapagos finches.
在同一个岛上 大达夫尼岛 在2006年 Well on the same island, Daphne Major, in 2006 ,
他们见证了 特征取代 they witnessed character displacement in action.
在很长一段时间里 只有一小群雀类住在岛上 For a long time, a small population of finches had the island
它们吃岛上的各类种子 to themselves, where they ate a variety of seeds,
包括短舌匹菊的种子 这种种子更大 including seeds of the fever plant, which were bigger and more
营养也比小种子多 nutritious than the smaller seeds that were available
但它们很难啄开这种种子吃 but were harder for the little finches to open.
在1982年, 一群体形更大的雀来到了岛上 Then in 1982 , a group of much bigger finches showed up
它们开始吃 on the island, and they began to commandeer
岛上供应充足的短舌匹菊种子 the island's abundant supply of fever plant seeds.
在短短的20年里 格兰特发现 以前那些小雀的喙 Within just 20 years, the Grants found, that the small finches'
变得更小了 beaks shrunk to allow them to specialize in eating only
它们现在专门吃那些更小, 营养更低的种子, the smaller, less nutritious seeds, but now the little finches
但现在 小种子全归它们吃了 had those seeds all to themselves.
这2个种群的性状分离了 The traits of the two populations had actually diverged
有助于资源的分配 to help facilitate the partitioning of resources.
看到了吗? 竞争也许很辛苦 但它也会让我们 See? Competition can be hard on us, but it also can make us
变成更好的人 或更好的雀 莺 袋鼠 老鼠 better people, or you know, finches or warblers or kangaroo mice.
但物种之间的相互作用 But there are also kinds of interspecific interaction in which
除了竞争 也有联手合作为生存而战 species actually join forces in the fight for survival.
这是避免冲突的终极方法 This is the ultimate in conflict-avoidance.
群落里的物种通过合作 In these cases, species in a community actually manage
来避免竞争 to avoid competition altogether by forming downright tight
合作至少会使得一方受益 relationships that benefit one, if not both of the parties involved.
你可能听说过这两种情况: You've heard of both of these cases:
1, 互利共生 First, mutualism,
意思是两个物种都有受益 where both species benefit,
2. 偏利共生, 其中1个物种有受益 and commensalism, where one species benefits
而另一个就像: "我无所谓" and other is kind of like, "Whatever."
互利共生在自然界到处都是 Mutualism abounds in nature,
那些经常看我们视频的同学 也应该很熟悉了 and for those who've been paying attention to Crash Course,
你听我说过很多很多次了 you've heard me talk about it many, many times before.
互利共生的一个典型例子是菌根 A prime example are mycorrhizae, the fungal roots that we talked
大概几星期前我们谈过了 真菌和植物的根缠在一起 about a few weeks ago where fungi and plant roots get entangled
互相给对方需要的营养. and essentially rub each other's backs for nutritious favors.
另一个你可能听说过的例子是 开花植物 Others you may have heard about include flowering plants
它们生产花蜜吸引授粉者 that produce nectars to attract pollinators, and that bear fruit
以及结出果实吸引动物 让动物帮助传播里面的种子. to attract animals to help spread the seeds inside.
而且通常情况下, 这种关系会变得不可或缺 Often times these relationships become rather needy,
拿白蚁举例 like in the case of termites.
他们需要消化系统里那些生产酶的微生物 They can't breakdown the cellulose in the wood they eat
分解木头里的纤维素 without the enzymes produced by microorganisms that live
不然白蚁会无法生存 inside their digestive systems.
没有小动物 大动物会死 Without the little critters, the bigger critters would die.
这种互相需要对方才能生存的关系叫做 专性互利共生 Such a needy relationship is called obligate mutualism.
相比之下 偏利共生是指其中一个物种受益 By contrast, commensalism is where one species definitely
而另一方好像没有受益也没有受损 benefits and the other isn't really hurt or helped.
当然 很难证明另一方到底是受益还是受损 Such neutrality, of course, is difficult to prove, because even
某些互利表面上看起来是良性互动 但它也有可能带来一些其他效果 a seemingly benign interaction probably has some effect.
拿藤壶举例 它附在灰鲸身上 把灰鲸当便车 Barnacles, for example, hitchhike on grey whales, getting a free
让自己在富含浮游生物的水里吃东西 ride through swathes of plankton-rich water for feeding.
显然这个关系里 藤壶有受益 While clearly a benefit to the barnacles, the relationship
这种关系 通常被认为是偏利共生的 is often considered commensal because the whales probably
因为鲸鱼也许根本不在乎 身上到底有没有藤壶 don't really care whether the barnacles are there or not.
也许它们在意? 藤壶可能会减慢鲸鱼的游速 Or do they? The barnacles might slow down the whale
但从另一方面来讲 as it swims through the water, but on the other hand,
它也许可以作为某种伪装 they might also serve as a type of camouflage from predators
比如让灰鲸看起来像逆戟鲸 使得灰鲸有优势 like orcas, in which case they confer an advantage.
但也许鲸鱼根本不在乎这事儿吧 So, it probably comes down to "meh" for the whale,
当你考虑物种互动的另一种可能性时 and when you consider all the other possibilities out there
"不在乎"也许不是一个坏选择 when species interact, "meh" isn't such a bad option.
下周 我们要去看喉咙 Especially considering that next week, we're going for the throat,
我的意思是 我们会探讨 杀与被杀的捕食动物世界 by which I mean, we'll be investigating the kill-or-be-killed
以及所有梦幻般的进化 world of animal predation, and all of the fantastic evolutionary
导致 changes it can trigger that lead to
生态群落里有更多的多样性 even greater diversity in ecological communities.
下集也许会有很多的血到处飙 There probably is going to be a lot of blood though,
也许你会想带上雨衣 so you might want to bring your poncho.
感谢收看本集生态学速成班 Thank you for watching this episode of Crash Course Ecology.
如果你想重看点什么 这边有张表 If you want to review anything, there's a table of contents over here
在 Youtube 才能点哦 for you to click on any of the parts that you may want to review.
感谢所有帮助我们制作视频的人 Much love and appreciation to all the people
感谢所有帮助我们制作视频的人 who helped us put this episode together.
如果你有问题 意见或想法 And if you have any questions or comments or ideas,
可以去 Facebook 或 Twitter 戳我们 you can leave them for us on Facebook or Twitter.
当然 也可以在下面留言. of course, down in the comments below.
@糖醋陈皮
懒，不做表了。。