首页
登录
职称英语
There can be few more depressing stories in the entire history of man’s expl
There can be few more depressing stories in the entire history of man’s expl
游客
2023-08-04
51
管理
问题
There can be few more depressing stories in the entire history of man’s exploitation of nature than the destruction of the unfortunate great whales. The whales have not only suffered untold cruelty but now face total extermination (灭绝). Already entire populations have been wiped out, and the only reason why no species has yet been finished off is due to the vastness and inaccessibility (难到达) of the oceans; a pocket or two somewhere has always managed to escape.
The basic rule of extinction is very simple: it occurs when a species mortality is continually greater than its recruitment. There are though, some very special additional factors in the case of whales.
Man does not actually have to kill the last whales of a species with his own hands, as it were, to cause its disappearance. Biological extinction will quickly follow the end of commercial whaling, should that end be due to a shortage of raw material, i.e. of whales. Whalers have long sought to defend their wretched trade by insisting that whales are automatically protected: as soon as they become rare, and therefore uneconomic to pursue, man will have no choice but to stop the hunting. That is a very nice theory, but it is the theory of an accountant and not of a biologist; only an accountant could apply commercial economics to complex biological systems. The reasons for its absurdity are many and varied. In the case of whaling it can be summed up in the following way.
When the stock has been reduced below a critical level, a natural, possibly unstoppable downward spiral begins because of three main factors. First, the animals lucky enough to survive the slaughter will be too scattered to locate one another owning to the vastness of the oceans. Secondly, whales being sociable animals probably need the stimulus of sizeable gatherings to induce reproductive behavior. It is quite likely that two individuals meeting through chance will not be compatible. (They can hardly be expected to be aware of their own rarity or to realize any need for adjusting their natural inclinations.) This is especially so with polygamous (一夫多妻的) species like the Sperm Whale. Thirdly, and perhaps most important in the long term, even allowing that the whales might still be able to band together in socially acceptable groups (thanks to their undeniably excellent communicative systems), there is a real danger that the whales’ gene pools would by then have sunk so low as to be biologically unviable. That is to say, the characteristics possessed by the original population would be whittled (削弱) down to those characters possessed by only the few remaining individuals. The result of such a biological disaster is inbreeding (近亲繁殖) , less ability to adapt to new conditions, and less individual variety. Three words can sum it up: protracted (长时间的) biological extinction. [br] How to judge if whales will become extinct?
选项
A、Its birth rate is continuously lower than its death rate.
B、Whales’ reproductive ability remains a very low rate.
C、The species of whales is doomed to extinction.
D、Whales’ death rate keeps an increasing trend.
答案
A
解析
细节题。根据题干中的extraction定位到第二段第一句。根据该句可知“物种灭绝的基本规律是很简单的:当一个物种的死亡率持续高于出生率时,灭绝就发生了。”A项符合文意,故选A。
转载请注明原文地址:https://tihaiku.com/zcyy/2896977.html
相关试题推荐
[originaltext]W:Hey,Mike!DidyouattendMr.Johnson’sseminarontheHistory
[originaltext]W:Hey,Mike!DidyouattendMr.Johnson’sseminarontheHistory
[originaltext]W:Hey,Mike!DidyouattendMr.Johnson’sseminarontheHistory
[originaltext]W:Hey,Mike!DidyouattendMr.Johnson’sseminarontheHistory
[originaltext]W:Hey,Tom!Iheardthatyouareauditingatthehistoryclass.
[originaltext]W:Hey,Tom!Iheardthatyouareauditingatthehistoryclass.
[originaltext]W:Hey,Tom!Iheardthatyouareauditingatthehistoryclass.
[originaltext]W:Hey,Tom!Iheardthatyouareauditingatthehistoryclass.
[originaltext]W:Hey,Tom!Iheardthatyouareauditingatthehistoryclass.
[originaltext]W:Hey,Tom!Iheardthatyouareauditingatthehistoryclass.
随机试题
In1620,102pilgrims,toescape______,sailedtotheNewWorldinashipcalled
现在国家离退休干部、知识分子和工商界人士“告老还乡”,发展家乡,充实家乡。“十三
交换机使能STP时,缺省情况下交换机的优先级为()。A.4096 B.819
修约间隔是1,修约57.46正确的是()。A.57.4 B.57.5 C.
治疗化脓性脑膜炎时头孢曲松钠的剂量是A.50mg/(kg·d) B.200mg
资本约束并不是控制银行操作风险的最好方法,应对操作风险的重要手段是严格的()。
炙甘草汤的功用是A.健脾益气,补肺宁嗽 B.益气健脾,养阴润肺 C.益气健脾
国民经济总体指标不包括()。A:国内生产总值B:工业增加值C:就业率D:通
下列四项中,错误的IP地址有()。 A.60.268.24.168 B.11
基础心理学是研究()。 (A)正常成人心理现象的心理学基础学科 (B
最新回复
(
0
)