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
2013-06-12
36
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 grand children. 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) chromosome, 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 lays eggs in a given larva, it would pay her to produce one male only, because this one male 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 for a 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 game theory, thereby providing important groundwork for the later development of strategy theory
答案
C
解析
转载请注明原文地址:https://jikaoti.com/ti/glRYFFFM
0
专业英语八级
相关试题推荐
AtachesstournamentinTunisiain1967,BobbyFischer,then24,waspittedagainstanotherAmericangrandmaster,SamuelReshe
Aftertakingabriefhiatustoweathertherecession,aninvasionofBritainbysomeofAmerica’sbest-knownretailbrands—incl
Althoughitmighthavehappenedanywhere,myencounterwiththegreenbananastartedonasteepmountainroadintheinteriorof
Languagecomprehensionisgenerallyviewedincognitivetheoryasconsistingofactiveandcomplexprocessesinwhichindividual
AccordingtoChitra,______charactersareconsideredtobenotwelldepicted.
Apidginisalanguagewithnonativespeakers:itisnoone’sfirstlanguagebutisacontactlanguage.Itistheproductofa
TheU.S.CentersforDiseaseControlsuggestedroutineHIVtestsfor
Theinterviewismainlyadiscussionconcerning
在法治和现代化建设上,新加坡堪称世界一流。用一个不太确切的比喻,新加坡真正达到了过去许多中国人梦寐以求的“中学为体、西学为用”的理想境界。这种境界应该是诞生华人先锋文化的理想土壤,但遗憾的是,新加坡的文化产品在全球华人社会中影响远不及香港和台湾地区,这里电
Bynow,itshouldcomeasnosurprisewhenscientistsdiscoveryetanothercaseofexperiencechangingthebrain.Fromthesenso
随机试题
期间核查定义正确的是________。
简述政治文化结构的特点。
下列情形中,应认定有因果关系的情形是:
设L是从点A(0,1)到点B(1,0)的直线段,则对弧长的曲线积分∫Lcos(x+y)出等于()。
独立的木材加工厂与周围其他设施、建筑之间的安全防火距离不小于()m。
借款人经营状况严重恶化,贷款人中止交付款项,借款人在合理期限内未恢复履行能力,这时贷款人()。
下列项目中,属于土地增值税征税范围的是()。
处于自律道德判断阶段的儿童的特征主要是()。
能影响水的电离平衡,并使溶液中的c(H+)>c(OH一)的操作是()。
A、Shehasnoneatpresent.B、Shehasboughtanewone.C、Shehasonlyanoldone.D、Herbrotherhasgivenherone.A
最新回复
(
0
)