共查询到20条相似文献，搜索用时 46 毫秒
1.
Herre EA 《Science (New York, N.Y.)》1985,228(4701):896-898
The effects of inbreeding and local mate competition have often been confounded in theoretical and empirical studies of sex ratio. A general model considering the interplay of their influences on sex ratio evolution is presented, and its predictions are compared with data collected from three fig wasp species. The results indicate that female fig wasps adjust the sex ratio of their offspring in response to both the intensity of proximate local mate competition and the level of inbreeding in the population. 相似文献
2.
When the relative fitness of male and female offspring varies with environmental conditions, evolutionary theory predicts that parents should adjust the sex of their offspring accordingly. Qualitative and even quantitative support for this prediction is striking in some taxa but much less convincing in others. Explaining such variation across taxa in the fit of sex ratio theory remains a major challenge. We use meta-analysis to test the role of two constraints in the evolution of sex ratios. Based on analysis of sex ratio skews in birds and wasps, we show that (i) mechanisms of sex determination do not necessarily constrain the evolution of sex ratio adjustment, and (ii) parental ability to predict their offsprings' environment influences the evolution of sex ratio patterns across taxa. More generally, our results show that multiple constraints may determine the precision of adaptation. 相似文献
3.
为了探究同种成虫的气味对普通大蓟马(Megalurothrips usitatus)交配期间性比调节的影响,设置对照（无气味）、已交配雌虫、未交配雌虫和已交配雄虫等4种气味源,分别处理单对刚羽化成虫24 h,然后用幼嫩豇豆(Vigna unguiculata)豆荚单头饲养被测雌虫,观测每日所产子代的性别和数量,计算子代性比。结果表明:已交配雌虫气味处理的子代雌虫数（22.80头）最少,跟其他处理差异显著。同对照的子代性比（0.31）相比,已交配雌虫和未交配雌虫的气味分别导致子代性比显著提高和降低,子代性比分别为0.48和0.22,而已交配雄虫气味对子代性比无显著影响。4个处理中,仅已交配雌虫气味处理的雌虫在产卵最后1天的日性比达到1.00,即雌虫体内的精子已消耗殆尽。成虫气味源对雌虫产卵天数没有明显影响。实验结果说明,普通大蓟马在交配期间能依靠嗅觉判别周边雌虫的交配状况,然后通过调控雌虫的获精数量,实现对子代性比的自调节。 相似文献
4.
寄主大小模型认为寄生蜂后代性比与寄主大小相关,寄生蜂倾向于在大寄主上产出更多雌性后代,在小寄主上产出更多雄性后代。探讨了以家蝇蛹为寄主时,蝇蛹佣小蜂后代产量和性比变化;单次寄生情况下,寄主大小及寄生顺序对寄生蜂后代性比等影响。结果表明,蝇蛹佣小蜂的产卵期为(8.93±3.34) d,单头雌蜂能产雌性后代(34.11±16.34)头和雄性后代(11.04±8.87)头,且雄性百分比为0.24±0.11。随成蜂日龄的增大,寄生蜂产生雄性后代的比率显著增加。蝇蛹佣小蜂在寄生家蝇蛹时,会优先选择寄生个体较大的蛹;在单次寄生的情况下,蝇蛹佣小蜂倾向于在较大的家蝇蛹内产出更多的雌性后代。 相似文献
5.
Male fertility and sex ratio at birth in red deer 总被引：1，自引：0，他引：1
Gomendio M Malo AF Soler AJ Fernández-Santos MR Esteso MC García AJ Roldan ER Garde J 《Science (New York, N.Y.)》2006,314(5804):1445-1447
Efforts to test sex ratio theory have focused mostly on females. However, when males possess traits that could enhance the reproductive success of sons, males would also benefit from the manipulation of the offspring sex ratio. We tested the prediction that more-fertile red deer males produce more sons. Our findings reveal that male fertility is positively related to the proportion of male offspring. We also show that there is a positive correlation between the percentage of morphologically normal spermatozoa (a main determinant of male fertility) and the proportion of male offspring. Thus, males may contribute significantly to biases in sex ratio at birth among mammals, creating the potential for conflicts of interest between males and females. 相似文献
6.
FENG Yan-ping GONG Yan-zhang Nabeel Ahmed Affara PENG Xiu-li YUAN Jin-feng ZHAO Rui-Xia Mohammed Yusuf Osman Jeffer ZHANG Shu-jun 《中国农业科学(英文版)》2006,5(7):545-549
The overall sex ratio of offspring （dead embryos and hatch chicks） from all the fertilized eggs of 140 hens collected for 30 days was studied using duplex PCR of certain fragments of sex chromosomes. Additional 894 dead embryos over a period of 21 days of incubation were also investigated to verify the sex ratio of the dead embryos. The sex of the early dead embryos was identified using this molecular sexing technique. The sex ratio of the hatch chicks and the total offspring of the hens investigated in this experiment did not differ from the expected sex ratio （i.e., 1：1）., However, the number of female dead embryos was significantly more than that of males. The data indicated that the different physiologic function of males and females contributed to female-biased mortality during incubation. It was also found by further analysis that the sex ratios of the offspring of some hens were significantly biased to female or male over the period investigated, which suggested that the sex ratio of offspring might be influenced by the maternal condition to some degrees. 相似文献
7.
Skinner SW 《Science (New York, N.Y.)》1982,215(4536):1133-1134
Facultative control of the sex ratio has been reported in the wasp Nasonia vitripennis. In a newly wild-eaught strain, females produced few or no male offspring and did not show the usual alterations of sex ratio in response to external conditions. The aberrant trait is inherited through females. 相似文献
8.
Clutton-Brock TH Russell AF Sharpe LL Young AJ Balmforth Z McIlrath GM 《Science (New York, N.Y.)》2002,297(5579):253-256
In cooperatively breeding birds, where helpers of both sexes assist with the provisioning and upbringing of offspring who are not their own, males tend to contribute more than females to rearing young. This sex difference has been attributed to paternity uncertainty, but could also occur because males contribute more where they are likely to remain and breed in their group of origin. In contrast to most birds, female meerkats (Suricata suricatta) are more likely to breed in their natal group than males. We show that female meerkat helpers contribute more to rearing young than males and that female helpers feed female pups more frequently than males. Our results suggest that sex differences in cooperative behavior are generated by sex differences in philopatry and occur because females derive greater direct benefits than males from raising recruits to their natal group. These findings support the view that direct, mutualistic benefits are important in the evolution of specialized cooperative behavior. 相似文献
9.
Kin selection and the evolution of monogamy 总被引：1，自引：0，他引：1
A two-locus genetic model is studied in which one locus controls the tendency of individuals to act altruistically toward siblings and the other locus controls the mating habits of females. It is demonstrated that genetic variation at the altruism locus is often sufficient to induce an increase in the frequency of genes that cause females to produce all of their offspring with a single mate. This occurs because of nonrandom associations that develop between genes that cause altruism and those that affect female mating behavior. The results provide a new explanation for the evolution of monogamy, and they suggest a previously unexplored mechanism for the evolution of a variety of other behavioral traits as well. 相似文献
10.
Burley N 《Science (New York, N.Y.)》1981,211(4483):721-722
Laboratory experiments performed on a monogamous estrildid, the zebra finch (Poephila guttata), indicate that sex ratio of offspring is affected by non-genetic markers (colored plastic leg bands) that vary in attractiveness to birds. Results suggest that natural selection favors individuals that produce offspring of the sex of the more attractive parent within a breeding pair. 相似文献
11.
根据2012年9-12月所罗门群岛海域采集的307尾长鳍金枪鱼样本,分析其性别比、性腺成熟度和性腺指数等繁殖生物学参数。结果表明：繁殖群体总性别比和性成熟个体性别比均不符合1：1（P〈0．05）,雄性个体比例大于雌性,性别比在产卵期间出现一定波动,但普遍小于1：1。性别比与个体大小密切相关,雄性比例随叉长增长而降低。性成熟度分析表明,产卵期间性成熟个体比例达到70％以上,其中存在大量的产卵后群体,未成熟比例较低。雌性不同性成熟度大小差异明显（P〈0．05）,但雄性并不明显（P〉0．05）。相同性成熟度雄性个体平均叉长均大于雌性,但并没有体现出一致的变化。雌、雄个体初次性成熟叉长分别为84．88cm和85．61cm。性腺指数（Gsi）在各性成熟度和叉长组间存在显著差异（P〈0．05）,雌性GSI大于1．2几乎全部为成熟个体,尤其GSI大于2普遍为即将产卵（V期）和产卵后（Ⅵ期）群体;雄性个体GSI普遍小于2,各叉长组雌性GSI普遍高于雄性,这表明雌性性腺发育较快。而调查期间9月GSI均值明显高于其他3月（P〈0．05）,综合分析认为该海域长鳍金枪鱼9—10月达到产卵高峰期。 相似文献
12.
Natural selection of parental ability to vary the sex ratio of offspring 总被引：67，自引：0，他引：67
Theory and data suggest that a male in good condition at the end of the period of parental investment is expected to outreproduce a sister in similar condition, while she is expected to outreproduce him if both are in poor condition. Accordingly, natural selection should favor parental ability to adjust the sex ratio of offspring produced according to parental ability to invest. Data from mammals support the model: As maternal condition declines, the adult female tends to produce a lower ratio of males to females. 相似文献
13.
Reproductive isolation between biological species is characterized by Haldane's rule, which states that the heterogametic sex (XY or ZW) suffers the most dysfunctional effects of hybridization. It has been hypothesized that, in addition to X-linked recessive genes, Haldane's rule also reflects the faster evolution of genes related to male reproduction (faster-male evolution). We used sex-reversed hybrid Xenopus to test faster-male evolution by examining the fertility of sex-reversed individuals with the genotype of the inverse phenotypic sex. Hybrid males are sterile and hybrid females are fertile irrespective of their genotypic sex. Gene expression profiles match these adult phenotypes, and our results demonstrate that faster-male evolution is the most likely mechanism producing hybrid male sterility. 相似文献
14.
[目的]探讨淡水和盐水对红罗非鱼和尼罗罗非鱼杂交子代的生长和发育的影响。[方法]在淡水和9‰盐度条件下通过红罗非鱼和尼罗罗非鱼的正反交试验,测定F1代成活率、日均增重量、特定生长率、体色比和雌雄比,并探讨淡水和9‰盐水对正反不同杂交组子代生长性状的影响。[结果]正反交淡水组F1代日均增重量、特定生长率均低于9‰盐水组,9‰盐水更能促进罗非鱼的生长。正交淡水组子代花斑色个体占82%,全红色与全黑色比例接近1∶1;9‰盐水组F1代以全红色和花斑色为主,分别占39%和48%,全黑色占13%;反交组无黑色子代出现,淡水组全红色个体占58%,花斑色占42%,而9‰盐度组以全红色个体为主,为84%。9‰盐水在一定程度上促进子代红色和花斑色个体的出现。正反交淡水组雌雄比例接近1∶2,9‰盐水组后代雌雄比例接近2∶3。9‰盐水促进子代雌性个体的出现。[结论]9‰盐水对罗非鱼种内正反杂交后代性别决定有一定影响。 相似文献
15.
西花蓟马与烟蓟马在紫甘蓝上的种间竞争 总被引：3，自引：0，他引：3
【目的】研究外来入侵物种西花蓟马与本地物种烟蓟马的种间竞争。【方法】在实验室条件下,将西花蓟马与烟蓟马的紫甘蓝种群作为研究对象,以不同的种群数量混合或单独饲养,繁殖1代或多代后检查并比较2种蓟马的产卵数量、种群数量及后代性比的变化情况,分析2种蓟马的种群增长竞争和生殖能力竞争。【结果】当烟蓟马与西花蓟马个体数分别以40﹕20、30﹕30、20﹕40的种群比例在紫甘蓝上共存竞争时,西花蓟马分别在4代、4代和5代后被烟蓟马完全取代,并且在竞争过程中伴随着西花蓟马种群雌虫比例的逐代下降。生殖能力竞争的结果表明烟蓟马可以显著降低西花蓟马的产卵量和后代的雌雄比例。当1对西花蓟马分别与1、2、3头烟蓟马雌虫共存时,西花蓟马的日均产卵量由5.7粒分别下降到2.6、1.9和0.8粒;1头西花蓟马雌虫分别与1、2、3头烟蓟马雌虫共存时,西花蓟马的日均产卵量由7.6粒分别下降到3.6、2.5和1.4 粒;而当1对西花蓟马分别与3头和5头烟蓟马雌虫共存时,西花蓟马后代的雌雄比例由3.1分别下降到2.4和1.3。【结论】在以紫甘蓝为寄主植物的竞争体系中,烟蓟马试验种群在短时间内取代了西花蓟马试验种群。烟蓟马除自身具有更强的繁殖力,其对西花蓟马生殖的抑制作用也是产生这一现象的重要原因。 相似文献
16.
17.
Acorn woodpeckers (Melanerpes formicivorus) live in family groups within which more than one female may lay eggs communally in a single nest. Communally nesting females are usually closely related and share evenly in nesting activities. Although birds of either sex may breed in their natal territory, reproductive inhibition of offspring by the presence of their parent of the opposite sex and dispersal by unisexual sibling units ensure that inbreeding between close relatives is rare. 相似文献
18.
Sex determination in an atherinid fish, the Atlantic silverside (Menidia menidia), is under the control of both genotype and temperature during a specific period of larval development. The sex ratios of the progeny of different females are variable and differ in their responsiveness to temperature. This demonstrates that sex ratio in fishes that normally have separate sexes can be influenced by the environment. 相似文献
19.
Although males and females occur in similar frequency in the broods of most scolytid beetles, certain individuals of several species produce offspring highly aberrant in the ratio of sexes-all or mostly female. In some instances this condition reflects gynogenesis (parthenogenesis stimulated by mating); in others, a maternally transmitted factor. 相似文献
20.
Mueller UG 《Science (New York, N.Y.)》1991,254(5030):442-444
In eusocial Hymenoptera, the haplodiploid system of sex determination creates relatedness asymmetries such that workers are more closely related on average to their sisters than to their brothers. For such societies, kin-selection theory and sex-ratio theory predict that workers maximize their inclusive fitness by biasing the investment sex ratio toward females. To test the prediction of sex-ratio biasing, relatedness asymmetries were experimentally manipulated in colonies of the primitively eusocial bee Augochlorella striata (Halictidae: Hymenoptera) by removing or not removing foundress queens. Queenright colonies (relatedness asymmetry present) produced a more female-biased sex ratio than did queenless colonies (relatedness asymmetry absent). Worker reproduction and unmated replacement queens can be discounted as alternative explanations. Workers therefore facultatively adjusted their colony's sex ratio and, in the presence of a relatedness asymmetry, biased the investment sex ratio toward their more closely related sisters and away from their more distantly related brothers. 相似文献