蜘蛛的性二型现象及其进化

对蜘蛛的性二型现象进行了初步的概括,并试图以食物对种群繁衍的影响为线索说明其进化机制。蜘蛛的性二型现象主要表现在体形大小上,一般雌性大于雄性;食物的数量和分布制约着蜘蛛性二型现象的进化。     

昆虫的雌雄嵌合现象

探讨了昆虫雌雄嵌合体的类型、类群、发生机制、对昆虫生物学的影响 ,以及其在胚胎发育学、比较形态学、神经系统调控机理上的应用。并对 1 980～ 2 0 0 0年《动物学记录》中收入的雌雄嵌合体记录进了行整理 ,共发现 1 3目 69科昆虫有雌雄嵌合体记载。文中还整理了中国现有的雌雄嵌合体记录     

昆虫的肢体自残现象

该文主要就昆虫的肢体自残现象发生的种类和虫态、被残器官和部位、自残发生的原因、自残对昆虫个体的有利及不利影响进行了综述,并简单地讨论了肢体自残现象在进化上的意义。     

昆虫体型及性体型二型性的地理变异

体型是昆虫基本的形态特性,它会影响到昆虫几乎所有的生理和生活史特性。同种昆虫不同地理种群在体型上常表现出明显的渐变,导致这些渐变的环境因素包括温度、湿度、光照、寄主植物、种群密度等,并且多种环境因素也会对昆虫种群内个体体型产生影响。雌雄个体的体型存在差异,称性体型二型性。性体型二型性也显示了地理差异。这些差异形成的途径已经得到详细的分析,其形成机制导致多个假说的提出,这些假说又在多种昆虫中得到验证。本文从同一种昆虫不同种群间、同一种群内、雌雄虫个体间3个水平,对种内昆虫体型变异的方式,影响昆虫种群间体型变异和种群内昆虫体型的变异的环境因素,以及昆虫性体型二型性及其地理变异的现象等方面的研究进行了综述,并对未来的相关研究提供了建议。     

梨小食心虫触角感受器雌雄二型的超微研究

梨小食心虫是果树上的一种重要害虫。本文采用扫描电子显微镜技术(SEM)对成虫离体触角外部形态进行观察,以Onagbola和Fadamiro(2008)为分类标准,对梨小食心虫的触角感受器重新进行分类。结果显示,梨小食心虫触角为线状,由柄节、梗节和鞭节构成,鞭节细分为38-45个亚节。雌、雄蛾共有8种触角感受器,分别为无孔栓锥形感受器、无孔B9hm's鬃毛、单孔刺形感受器、多孔毛形感受器、多孔锥形感受器、多孔腔锥形感受器、多孔耳形感受器和芽孢形感受器(只在雌蛾触角上观察到)。感受器在类型、形态和数量上存在雌雄二型现象。耳形感受器数量在雌雄间差异显著,雌雄蛾刺形感受器、栓锥形感受器、毛形感受器、锥形感受器、腔锥形感受器长度差异显著,并对其功能进行了推测。     

基于形态学证据的长足虻科系统发育研究(双翅目,短角亚目)

试图根据成虫形态学证据探讨长足虻科各亚科之间的系统关系,同时检验各个亚科的单系性.在比较形态学研究基础上,同时参考前人有关长足虻科高阶元分类的研究结果,筛选出42个来自头部、胸部(包括足和翅)、腹部、雌性和雄性外生殖器在亚科水平的分类特征,为了考察亚科的单系性,也包括亚科的自有衍征;运用支序分类的方法,首次分析并讨论了世界长足虻科17个亚科之间的系统发育关系.结果表明,长足虻科是一个严格的单系群,其支持的共同衍征为体色金绿,亚前缘脉端部与第1径脉中部愈合,前缘脉接近肩横脉处有1个缺刻,第2基室与盘室愈合,臀室短小、终止于径脉分叉点之前,雄性外生殖器明显向下或向前弯折,生殖背板具生殖孔,下生殖板与第9背板愈合.金长足虻亚科Sciapodinae腋瓣发达,中脉分叉,为最基部的支系,是最原始的亚科;而长足虻科的其他亚科构成一单系群,其共同衍征为腋瓣不明显,中脉不分叉.斜脉长足虻亚科Plagioneurinae也比较原始,是靠基部的支系,支持其单系性的特征为腹部第7～8节膜质化,生殖孔基位.异长足虻亚科Diaphorinae和锥长足虻亚科Rhaphiinae以及斯长足虻亚科Stolidosomatinae和合长足虻亚科Sympycninae分别构成姊妹群关系,斯长足虻亚科Stolidosomatinae的两个属Pseudosympycnus和Stolidosoma系统地位还有待进一步研究.此外,巴长足虻亚科Babindellinae、聚脉长足虻亚科Medeterinae和寇长足虻亚科Kowmunginae构成单系群,其共同衍征为臀脉短或不明显,无后顶鬃.研究所用标本大部分保存在中国农业大学昆虫标本馆,包括与美国史密森研究院和澳大利亚博物馆交换而来的标本,部分标本保存在比利时皇家科学院.     

昆虫在多次交配与精子竞争格局中的雌雄对策

绝大多数昆虫雌性一生中不但与不同雄性交配许多次,而且在其特殊器官中还可长期贮藏雄性精子,因此来自不同雄性的的精子在与雌性卵子受精时发生激烈的精子竞争。本文综述了昆虫在多次交配与精子竞争格局中的雌雄对策。雄性对策表现在对自身与配偶身体质量状况的正确评估、精子竞争风险预测、精子异型及延长交配时程和配后保护等,雌性对策则表现在对雄性质量状况的正确评估、对精液的主动操纵及精子偏向性等,从而很好地适因多次交配和精子竞争而带来的强烈自然选择和性选择压力。     

小异长足虻属额宽率的进化意义及一新属五新种记述(双翅目,长足虻科,异长足虻亚科)

研究发现小异长足虻属Chrysotus Meigen,1824中某些类群所具备的"额渐次变狭,颜颇宽、略下凹、两侧缘平行"的额、颜构造特征与异长足虻属Diaphorus Meigen,1824完全相同,该特征在两者中应属系统发育特征;并主要据此特征将小异长足虻属中凡具备"额渐次变狭,颜颇宽、略下凹、两侧缘平行"特征的类群分离出来,建立了变长足虻属Dubius gen.nov.,并附新属5新种记述:秋变长足虻D.autumnalus sp.nov.,曲变长足虻D.curtus sp.nov.,额变长足虻D.frontus sp.nov.,红崖变长足虻D.hongyaensis sp.nov.和亚曲变长足虻D.succurtus sp.nov.。根据变长足虻属,仅分布于新热带区和属东洋区的中国西南地区推测其可能起源于南方古陆(冈瓦纳古陆),并早在冈瓦纳大陆裂解前即向东洋区扩散。模式标本保存于作者所在单位。     

Sexual size dimorphism in parasitoid wasps

Sexual dimorphism in body length and proportion of overlap between the ranges of body length for males and females were estimated for 361 species of parasitoid wasps from 21 families. In most species, females are generally larger than males, though the range of male and female sizes overlap. Species in the family Ichneumonidae differ significantly from species in other families in three ways: (1) ichneumonids on average are larger, (2) in most species, females are generally smaller than males, and (3) on average, proportion overlap between the ranges of body length for males and females is greater. At present, there is a paucity of life history data on parasitoid wasp species for which size dimorphism is known. Thus it is not clear why ichneumonids differ from species in other families. Possible evolutionary explanations for variation in dimorphism among parasitoid wasp species are discussed.     

Sexual selection,sexual dimorphism and plant phylogeny

Summary Darwin examined sexual dimorphism in animals, arguing that sexual selection was important in the evolution of such dimorphism. Sexual dimorphism in plants may have parallel causes and costs.The processes that contribute to sexual dimorphism may also lead to speciation and morphological differences among related species, as argued originally by Darwin. Where sexes are separate and dimorphism is well-developed, males of related animal species (both vertebrate and invertebrate) are often strikingly different from each other, while females may be virtually indistinguishable. A similar pattern may exist in plants: it is frequently the males (of dioecious taxa) or the male portions of the flower (in co-sexual flowers) that apparently have diversified. I suggest that the similarity of pattern may be accounted for by a similarity of process.In addition, sexual selection may have contributed to certain evolutionary trends within the angiosperms and, indeed, to angiosperm radiation.     

鳄蜥的两性异形

通过比较鳄蜥的体型与头部大小等特征的差异,研究了鳄蜥的两性异形情况.结果表明:性成熟鳄蜥个体体色差异显著,成年雄性头胸部腹面呈鲜红色或浅蓝色,而雌性为浅黄色或淡红色;成年雄性头部显著大于成年雌性(头长(HL),P＜0.001;头宽(HW),P＜0.001),成年雌性腹部长(AL)显著大干成年雄性(P=0.018);而成...     

Sexual dimorphism in growth from 8 to 18 years

A mixed longitudinal study of growth and development has been conducted, centering on an analysis of differences based on sex between the ages of 8 and 18 years for a series of 12 anthropometric indicators. The sample consisted of 50 girls and 63 boys. Proceeding from the specific differences, the variables can be divided into four groups with identical structures of differences. The first group comprises measurements of body height, body mass, shoulder width and pelvic span, all of which have higher values in boys between 8 and 10 and between 14 and 18. Between the ages of 11 and 13 girls are taller, heavier, with broader shoulders and pelvises. The second group covers measurements of subcutaneous fat. which are higher for girls throughout the period under review. The third group of indicators comprises the diameters of the joints of the extremities, i.e. of elbows and knees. Throughout the period under observation, these measurements are higher in boys, with the absolute differences between the sexes being the same at the age of 8 and ten years later. The fourth group consists of circumferences measurements of the extremities. It was found that calf circumferences manifested a specific inversion of the curves between 14 and 15, with girls showing a larger calf circumference up to the age of 14, and boys from the age of 15. The effect of earlier onset of puberty in girls was found to be reflected only on the inversion of the curve flow of the variables from the first group.     

Sexual dimorphism and dental variability in platyrrhine primates

Leutenegger and Cheverud (1982, 1985) propose a hypothesis to explain why larger primates are more sexually dimorphic in body weight and canine size. Their hypothesis states that any factor selecting for an evolutionary increase in body size will produce an increase in sexual dimorphism in any character if either heritability or phenotypic variability is greater in males than in females for that character. They cite no evidence for heritability but give some data to suggest that males are, in fact, more variable than females. We test the latter proposition more fully using measurements on the dentitions of platyrrhine primates. Male and female phenotypic variances are not significantly different in most cases. Cases of greater male phenotypic variance are not limited to sexually dimorphic species. We conclude that the hypothesis of Leutenegger and Cheverud does not explain the observed patterns of dental sexual dimorphism, at least in platyrrhines.     

Sexual dimorphism and allometry of external morphology in Oreochromis mossambicus

Sexual dimorphism in growth of conventional morphometric characters was investigated in juveniles and young adults (size range: 31 to 91 mm) of Oreochromis mossambicus . A closely associated set of traits was identified that shows sexually dimorphic growth, which was positively allometric in the males. These traits correspond to two different morphological complexes: jaw structure and anal/dorsal fins. The best sex discriminators among this set of traits were premaxilla width, anal fin height and snout length. These findings may be explained in terms of intra– and inter–sexual selection acting together and favouring males with strong and large mouths and high dorsal and anal fins, traits that are important in agonistic displays (jaw and fins), fighting and nest digging (jaw).     

Sexual dimorphism of body size and shell shape in European tortoises

Adult body size and shape were examined in almost 1400 individuals of the tortoises Testudo graeca , T. hermanni and T. marginata from Greece. The size at maturity was greater in females than in males in all three species. Maximum and mean adult sizes were also greater in females than in males in T. graeca and T. hermanni . Males grew to a larger size than females in T. marginata , and mean adult size was similar in the sexes in this species. Sexual dimorphism of shape (adjusted for size covariate) was shown in most of the characters examined, and the degree of this dimorphism differed significantly among the three species. Differences were related to their contrasting courtship behaviours: horizontal head movements and severe biting in T. marginata , vertical head bobs and carapace butting in T. graeca , and mounting and tail thrusting in T. hermanni . There was no difference in the frequency of observations of courtship or fighting among the three species, but courtship was about 10 times more common than combat in males. All species showed greatest courtship activity in autumn; copulation was rarely observed in T. hermanni (only 0.36% of courting males) and not seen in the other species in the field. Observations made throughout the activity season indicated that feeding was equally common in males and females in all three species. Differences in shape were more likely to be the result of sexual selection than of natural selection for fecundity. Detailed predictions are made for sexual dimorphism of other characters in these species.