在2014年6月15日的托福閱讀考試中有這樣一道題：自然選擇所帶來的相關(guān)滅絕。針對(duì)這道托?？碱}，出國(guó)留學(xué)網(wǎng)(www.liuxue86.com)小編來為大家普及一下關(guān)于自然選擇的背景知識(shí)，這樣有助于考生在面對(duì)這類題目時(shí)方便作答。小編在此提醒大家：本文討論的是自然選擇這個(gè)?？荚掝}，該話題歷年來都是?？荚掝}。
托福閱讀真題再現(xiàn)：
版本一：
2，自然選擇的限制，進(jìn)化并非好處，很大可能導(dǎo)致滅絕。分述前者進(jìn)化會(huì)對(duì)后代造成限制，器官間的相互作用。最后說是一些列的偶然，包括進(jìn)化等等造就了生存下來的早期生物
版本二：
natural selection不是總是靠譜的因?yàn)閾?jù)記錄地球上百分之九十九點(diǎn)幾的出現(xiàn)過的進(jìn)化分支(不知道中文怎么說原文也不記得了可能是evolutionary line?)都滅絕了 這好像是達(dá)爾文說的 大概說進(jìn)化好多時(shí)候不是按natural selection或者進(jìn)化不到perfection.原因一是基因結(jié)構(gòu)的形成互相影響(interact)，不會(huì)輕易因?yàn)?natural selection改變。還說早期的改變會(huì)影響后來的進(jìn)化，舉例說脊椎動(dòng)物和另一種估計(jì)是節(jié)肢什么的動(dòng)物分別進(jìn)化了internal和external的骨骼，導(dǎo)致后來脊椎動(dòng)物很多長(zhǎng)得很大個(gè)，節(jié)肢動(dòng)物頂多有只大個(gè)的螃蟹噗哈哈哈
還有一個(gè)原因好像是自然環(huán)境因素，這個(gè)記不清了似乎說自然環(huán)境變了動(dòng)物fit in environment也變反正是說可能比起由于natural selection產(chǎn)生的變化多??還有什么面對(duì)環(huán)境變化幸存的動(dòng)物后代可能失去一些基因??
版本三：
題目好像是EXTINCTION 講的是生物進(jìn)化的知識(shí) 第一段亮觀點(diǎn)進(jìn)化不一定都是物種的選優(yōu)(原詞是perfection)達(dá)爾文的進(jìn)化論雖然對(duì)滴但是也有99.9%的evolutionary line(原詞好像是這個(gè)) 滅絕了 主題就是自然選擇不一定都是好事 可能滅絕一些
往下繼續(xù)是一些比較零散的信息： 有一個(gè)詞匯題resistance 正確選項(xiàng)是opposition 那個(gè)詞附近是這么個(gè)事情 這段的主題是interation 各個(gè)結(jié)構(gòu)和器官之間不可能相互independent 一個(gè)器官或者組織不足以應(yīng)對(duì)自然界的變化 所以器官之間的resistance會(huì)在某種程度上決定這個(gè)物種的去留
再往下：提到了另一個(gè)因素 就是Chance 就是一個(gè)物種能不能留下也得靠人品 有一個(gè)詞匯題indiscriminate答案應(yīng)該是random 那個(gè)附近說了這么個(gè)事情 就是一些大災(zāi)難用的是catastrophe會(huì)是的一些就算是比較NB的物種也完蛋 就是一視同仁不管是誰 所以用了indiscriminate這個(gè)詞
補(bǔ)充resistance的那一段 還提到了genotype基因型 好像是這個(gè)意思 在進(jìn)化過程中優(yōu)秀的基因會(huì)保留 不行的直接完蛋
解析：
本文討論的是自然選擇這個(gè)?？荚掝}，該話題歷年來都是?？荚掝}。與以往不同的是，本文側(cè)重的角度是自然選擇所帶來的相關(guān)滅絕，而且沒有像之前的話題那樣結(jié)合某種物種來討論，同學(xué)們?cè)诮忸}中的關(guān)鍵是，閱讀完英文后，能對(duì)應(yīng)的理解所描述表達(dá)的概念，對(duì)同學(xué)們抽象內(nèi)容理解能力也是一定的挑戰(zhàn)。
托福參考閱讀：
Natural selection acts solely through the preservation of variations in some way advantageous, which consequently endure. Owing to the high geometrical rate of increase of all organic beings, each area is already fully stocked with inhabitants; and it follows from this, that as the favoured forms increase in number, so, generally, will the less favoured decrease and become rare. Rarity, as geology tells us, is the precursor to extinction. We can see that any form which is represented by few individuals will run a good chance of utter extinction, during great fluctuations in the nature of the seasons, or from a temporary increase in the number of its enemies. But we may go further than this; for, as new forms are produced, unless we admit that specific forms can go on indefinitely increasing in number, many old forms must become extinct. That the number of specific forms has not indefinitely increased, geology plainly tells us; and we shall presently attempt to show why it is that the number of species throughout the world has not become immeasurably great.
We have seen that the species which are most numerous in individuals have the best chance of producing favourable variations within any given period. We have evidence of this, in the facts stated in the second chapter showing that it is the common and diffused or dominant species which offer the greatest number of recorded varieties. Hence, rare species will be less quickly modified or improved within any given period; they will consequently be beaten in the race for life by the modified and improved descendants of the commoner species.
From these several considerations I think it inevitably follows, that as new species in the course of time are formed through natural selection, others will become rarer and rarer, and finally extinct. The forms which stand in closest competition with those undergoing modification and improvement will naturally suffer most. And we have seen in the chapter on the Struggle for Existence that it is the most closely-allied forms,—varieties of the same species, and species of the same genus or of related genera,—which, from having nearly the same structure, constitution, and habits, generally come into the severest competition with each other; consequently, each new variety or species, during the progress of its formation, will generally press hardest on its nearest kindred, and tend to exterminate them. We see the same process of extermination amongst our domesticated productions, through the selection of improved forms by man. Many curious instances could be given showing how quickly new breeds of cattle, sheep, and other animals, and varieties of flowers, take the place of older and inferior kinds. In Yorkshire, it is historically known that the ancient black cattle were displaced by the long-horns, and that these “were swept away by the shorthorns” (I quote the words of an agricultural writer) “as if by some murderous pestilence.”
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