时差N小时 种群动态进化

Until recently, many ecologists didn't study the effect of evolution on population dynamics¹ because evolution is much slower than the predator²-prey cycle.

直到最近，许多生态学家都没有研究种群动态进化所带来的影响，因为进化的速度远远慢于捕食的周期。

But a study suggests that adaptive evolution might actually play a role in the dynamics ofthe predator-prey relationship.

但是研究表明，适应性进化可能影响着掠食者与被掠食者之间的动态。

Cornell University biologists studied the population dynamics of green algae³ and rotifers, the microscopic⁴ aquatic⁵ animals that feed on them.

康乃尔大学的生物学家研究了以绿藻为食的轮虫的种群动态。

They expected that the rotifers would eat the algae and multiply until the algae population crashed.

他们预测，轮虫将会吃掉绿藻并繁衍后代直到绿藻的种群锐减。

This would then cause the rotifer population to crash, which would allowthe algae population to recover, and the whole cycle to begin again.

由于绿藻的减少，轮虫的种群也会锐减，这时绿藻种群便开始恢复，整个循环周期便又开始了。

What they observed, however, was that there was some lag between the time the algae population reached a certain density⁶ and the time the rotifer population began its recovery.

但是他们观察到在绿藻种群到达一定的密度之后，轮虫种群并没有立刻开始恢复。

Why? And how does evolution fit into all this?

为什么呢？进化过程是如何与之一致的呢？

Well, it turns that some algal cells are resistant⁷ to digestion⁸, although this resistance comes at a cost: they reproduce more slowly.

实际上，有些藻类细胞会对消化产生抵抗性。尽管这些抵抗也是有代价的：它们的繁殖更加缓慢。

As the more dominant⁹, non-resistant strains of algae crashed, the resistant algal cells began cloning themselves more rapidly, and this temporarily stabilized¹⁰ the algae population.

由于处于优势，不抗消化的绿藻品种数量减少，抗消化的绿藻细胞开始更加快速的繁殖，这就暂时稳定了绿藻种群。

In the meantime, the rotifer population crashed because the rotifers had less to eat,allowing the non-resistant strains of algae to recover.

同时，轮虫种群随着它们食物的减少而减少，这就让不抗消化的绿藻品种开始恢复。

Once the non-resistant algae became common again, the rotifer population increased, completing the cycle.

一旦不抗消化的绿藻又变得普遍了，轮虫种群就开始增长，完成整个循环周期。

So basically, adaptive evolution enabled the algae population to reestablish itself by delaying the time it took the predator population to recover.

因此，适应性进化使得绿藻种群能够通过拖延捕食者种群恢复的时间来重建自己。

Understanding the effects of adaptive evolution may help scientists to better understand the behavior of drug-resistant bacteria and outbreaks of disease.

对适应性进化影响的了解将会帮助科学家更好的明白抗药菌的行为以及疾病的爆发。

1 dynamics   

n.力学，动力学，动力，原动力；动态

参考例句：

• In order to succeed,you must master complicated knowledge of dynamics.要取得胜利，你必须掌握很复杂的动力学知识。
• Dynamics is a discipline that cannot be mastered without extensive practice.动力学是一门不做大量习题就不能掌握的学科。

2 predator   

n.捕食其它动物的动物；捕食者

参考例句：

• The final part of this chapter was devoted to a brief summary of predator species.本章最后部分简要总结了食肉动物。
• Komodo dragon is the largest living lizard and a fearsome predator.科摩多龙是目前存在的最大蜥蜴，它是一种令人恐惧的捕食性动物。

3 algae   

n.水藻，海藻

参考例句：

• Most algae live in water.多数藻类生长在水中。
• Algae grow and spread quickly in the lake.湖中水藻滋蔓。

4 microscopic   

adj.微小的，细微的，极小的，显微的

参考例句：

• It's impossible to read his microscopic handwriting.不可能看清他那极小的书写字迹。
• A plant's lungs are the microscopic pores in its leaves.植物的肺就是其叶片上微细的气孔。

5 aquatic   

adj.水生的，水栖的

参考例句：

• Aquatic sports include swimming and rowing.水上运动包括游泳和划船。
• We visited an aquatic city in Italy.我们在意大利访问过一个水上城市。

6 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。

7 resistant   

adj.(to)抵抗的，有抵抗力的

参考例句：

• Many pests are resistant to the insecticide.许多害虫对这种杀虫剂有抵抗力。
• They imposed their government by force on the resistant population.他们以武力把自己的统治强加在持反抗态度的人民头上。

8 digestion   

n.消化，吸收

参考例句：

• This kind of tea acts as an aid to digestion.这种茶可助消化。
• This food is easy of digestion.这食物容易消化。

9 dominant   

adj.支配的，统治的；占优势的；显性的；n.主因，要素，主要的人(或物)；显性基因

参考例句：

• The British were formerly dominant in India.英国人从前统治印度。
• She was a dominant figure in the French film industry.她在法国电影界是个举足轻重的人物。

10 stabilized   

v.（使）稳定， （使）稳固( stabilize的过去式和过去分词 )

参考例句：

• The patient's condition stabilized. 患者的病情稳定下来。
• His blood pressure has stabilized. 他的血压已经稳定下来了。 来自《现代英汉综合大词典》