首页
登录
职称英语
The evolution of sex ratios has produced, in most plants and animals with sep
The evolution of sex ratios has produced, in most plants and animals with sep
游客
2023-12-11
62
管理
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. [br] According to the passage, successful game strategy depends on______.
选项
A、the ability to adjust one’s behavior in light of the behavior of others
B、one’s awareness that there is safety in numbers
C、the degree of stability one can create in one’s immediate environment
D、the accuracy with which one can predict future events
答案
A
解析
转载请注明原文地址:http://tihaiku.com/zcyy/3263627.html
相关试题推荐
FiveTipsforStudyingAmericanRevolutionAmericanRevolution—
FiveTipsforStudyingAmericanRevolutionAmericanRevolution—
FiveTipsforStudyingAmericanRevolutionAmericanRevolution—
FiveTipsforStudyingAmericanRevolutionAmericanRevolution—
FiveTipsforStudyingAmericanRevolutionAmericanRevolution—
WhendidtheEnglishBourgeoisRevolutiontakeplace?A、In1640.B、In1641.C、In
HowDeerSurviveWinterLikemostofthewildanimals,deersurviv
HowDeerSurviveWinterLikemostofthewildanimals,deersurviv
HowDeerSurviveWinterLikemostofthewildanimals,deersurviv
HowDeerSurviveWinterLikemostofthewildanimals,deersurviv
随机试题
Thetwofiendswereamazedat____________________(自从他们最后一次见面以来过了多长时间).howmucht
“综合治理”要求运用()等多种手段,充分发挥社会、职工、舆论监督各个方面的作用
有关麻醉性镇痛药叙述正确的是()A.属周围神经镇痛药 B.立体专一性阿片受
可降低血浆同型半胱氨酸浓度,有助于预防老年人动脉粥样硬化的一组维生素是( )。
患者头痛而晕,心悸不宁,神疲乏力,面色无华,舌淡苔薄白,脉细弱。治疗应首选A.
A.胰岛素绝对不足 B.胰岛素相对不足 C.呼吸带烂苹果味 D.多尿、多饮
患者女,31岁,因化脓性扁桃体炎需注射青霉素,皮试阴性。肌内注射青霉素后5分钟,
小儿,3岁,体重14kg,身高90cm,牙齿20颗,可考虑为A:佝偻病 B:营
在一个经济体中,影响家庭消费支出的最重要因素是()。A.可支配收入 B.利率水
如图7-8所示,两电路相互等效,由图(b)知,流经10Ω电阻的电流IR=1A,
最新回复
(
0
)