首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
The evolution of sex ratios has produced, in most plants and animals with separate sexes, approximately equal numbers of males a
The evolution of sex ratios has produced, in most plants and animals with separate sexes, approximately equal numbers of males a
admin
2005-11-28
89
问题
The evolution of sex ratios has produced, in most plants and animals with separate sexes, approximately equal numbers of males and females. Why should this be so? Two main kinds of answers have been offered. One is couched in terms of advantage to population. It is argued that the sex ratio will evolve so as to maximize the number of meetings between individuals of the opposite sex. This is essentially a "group selection" argument. The other, and in my view correct, type of answer was first put forward by Fisher in 1930. This "genetic" argument starts from the assumption that genes can influence the relative numbers of male and female offspring produced by an individual carrying the genes. That sex ratio will be favored which maximizes the number of descendants an individual will have and hence the number of gene copies transmitted. Suppose that the population consisted mostly of females, then an individual who produced sons only would have more grandchildren. In contrast, if the population consisted mostly of males, it would pay to have daughters. If, however, the population consisted of equal numbers of males and females, sons and daughters would be equally valuable. Thus a one-to-one sex ratio is the only stable ratio; it is an "evolutionarily stable strategy". Although Fisher wrote before the mathematical theory of games had been developed, his theory incorporates the essential feature of a game that the best strategy to adopt depends on what others are doing.
Since Fisher’s time, it has been realized that genes can sometimes influence the chromosome or gamete in which they find themselves so that the gamete will be more likely to participate in fertilization. If such a gene occurs on a sex-determining(X or Y)chromo-some, then highly aberrant sex ratios can occur. But more immediately relevant to game theory are the sex ratios in certain parasitic wasp species that have a large excess of females. In these species, fertilized eggs develop into females and unfertilized eggs into males. A female stores sperm and can determine the sex of each egg she lays by fertilizing it or leaving it unfertilized. By Fisher’s argument, it should still pay a female to produce equal numbers of sons and daughters. Hamilton, noting that the eggs develop within their host —the larva of another insect — and that the newly emerged adult wasps mate immediately and disperse, offered a remarkably cogent analysis. Since only one female usually eggs in a given larva, it would pay her to produce one male only, because this one could fertilize all his sisters on emergence. Like Fisher, Hamilton looked for an evolutionarily stable strategy, but he went a step further in recognizing that he was looking strategy.
The author suggests that the work of Fisher and Hamilton was similar in that both scientists______.
选项
A、conducted their research at approximately the same time
B、sought to manipulate the sex ratios of some of the animals they studied
C、sought an explanation of why certain sex ratios exist and remain stable
D、studied reproduction in the same animal species
答案
C
解析
从文中的最后一句话“Like Fisher,Hamilton looked for an evolutionarily stable strategy, but he went a step further in recognizing that he was looking strategy.”可知,C项为正确答案。
转载请注明原文地址:https://kaotiyun.com/show/6FIO777K
0
考博英语
相关试题推荐
ElectronicCommerceAtthebeginningofthe1990s,noonehadheardoftheInternet,apartfromafewresearchersandacadem
Readthearticlebelowaboutmarketresearch.Inmostofthelines(34-45),thereisoneextraword.Itiseithergrammatical
Readthearticlebelowaboutmarketresearch.Inmostofthelines(34-45),thereisoneextraword.Itiseithergrammatical
HowtoapproachListeningTestPartTwo•ThispartoftheListeningTesttestsyourunderstandingofnumbers,namesandspelling
HowtoapproachListeningTestPartTwo•ThispartoftheListeningTesttestsyourunderstandingofnumbers,namesandspelling
HowtoapproachListeningTestPartTwo•ThispartoftheListeningTesttestsyourunderstandingofnumbers,namesandspelling
HowtoapproachListeningTestPartTwo•ThispartoftheListeningTesttestsyourunderstandingofnumbers,namesandspell
HowtoapproachListeningTestPartTwo•ThispartoftheListeningTesttestsyourunderstandingofnumbers,namesandspell
HowtoapproachListeningTestPartTwo•ThispartoftheListeningTesttestsyourunderstandingofnumbers,namesandspell
随机试题
认为支付薪酬的依据应当只是员工的技能、经验、绩效或职责等因素,而不是其他各种似是而非的因素的道德观是()
哪项指标对不典型甲亢诊断最有意义
急性肾盂肾炎的治愈标准是
凸阵扫描探头,临床常用于何部位的检查
46.肺痈患者脓血浊痰吐入水中后,下沉的部分是
甲(18岁)、乙(14岁)因故将丙打成轻伤。提起公诉后,法院同意适用简易程序进行审理。与此同时,丙对甲、乙提起附带民事诉讼。在本案中以下哪些人员可以不参加法庭审理?
设齐次方程组,当方程组有非零解时,k值为()。
中央财政与地方财政之间、地方上级财政与下级财政之间没有整体关系,政府间的财政联系主要依靠分税制和转移支付制度来实现。这种财政管理体制称为()。
劳动能力鉴定中,对生活自理障碍的等级鉴定,不包括()。
求的渐近线.
最新回复
(
0
)