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。     

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     

昆虫趋光的性别差异及其影响因素

趋光是众多夜行性昆虫的主要行为特征之一.研究表明:许多夜行性昆虫的趋光存在明显的性别差异现象,而这种差异受多种因素的影响.本文从雌雄成虫飞行能力差异导致其飞行距离与高度的不同、雌雄成虫复眼结构差异导致其对光源反应不同,以及雌雄成虫对光源和环境刺激的敏感性不同等方面综述了导致昆虫趋光性别差异的因素,并探讨了昆虫趋光性别差异的应用及今后研究方向.     

罗汉果叶片挥发性成分与访花昆虫: 雌雄株差异及其生态影响

为探究罗汉果(Siraitia grosvenorii)自然授粉不良的形成原因,该文以罗汉果品种“大地二号”的种苗为材料,采用定点定时方法调查罗汉果雌雄株访花昆虫,同时利用GC-MS对雌雄株叶片的挥发性成分进行比较分析。结果表明:在雄株上观察到访花昆虫102种,分属于8目29科,其中包括蜜蜂科、眼蝶科、夜蛾科和天蛾科等传粉昆虫类群; 在雌株上观察到访花昆虫69种,分属于7目16科,但未观察到上述传粉昆虫类群。雄株访花昆虫的物种丰富度、多度和Shannon-Wiener多样性均显著高于雌株(P<0.05),Jaccard相似性分析显示,雌株和雄株访花昆虫达到中等不相似水平。在雄株叶片中鉴定出挥发性成分17种,优势成分为萜烯类化合物,占总含量的67.31%; 在雌株叶片中鉴定出挥发性成分12种,优势成分为烷烃类化合物,占总含量的44.27%。雄株具有较多特有成分,包括7种萜烯类和3种酯类成分,占总体成分的45.45%; 雌株的特有成分较少,包括4种烷烃类和1种酯类成分,占总体成分种类的22.72%。Jaccard相似性分析显示,雌株和雄株的挥发性成分总体上达到中等不相似水平,其中萜烯类和酯类的相似度更低,达到极不相似水平。进一步分析表明,在罗汉果雌雄株之间,由于挥发性化合物在优势成分上的重要差异,以及特有成分的大量存在,可能导致了它们访花昆虫类群的显著差异,进而影响了罗汉果的自然传粉过程。     

双翅目害虫性别分离技术的研究进展及展望

在过去的几十年中,昆虫不育技术(sterile insect technique, SIT)已被用于防治农业害虫和人类健康相关的病媒害虫。相较于传统的农药控制策略,昆虫不育技术具有物种特异性和环境友好型等特点。通过释放不育雄虫的昆虫不育技术的主要障碍是在大规模饲养阶段将雄性与雌性分离,从而提高这些防治方法的成本效率,并防止释放携带和传播疾病的雌性群体。目前大多数针对双翅目害虫的遗传防治策略没有进行性别分离,少数害虫性别分离方法是基于蛹的大小或者雌雄蛹羽化时间差异进行人工识别和机械识别分离。双翅目昆虫性别决定及分化分子机制多种多样,其性别决定主要信号差异巨大,其多种性别决定基因已用于性别分离系统的开发。性比失衡性别分离策略通过破坏性别决定途径关键基因的表达获得雄性偏向后代,雌性条件性致死分离策略利用性别决定关键基因的雌雄选择性剪接差异实现性别分离,这两种性别分离策略目前正在害虫不育防治中接受大规模饲养应用评估,而基于双翅目昆虫雌雄性二态和基因标记发展的可视化性别分离策略也已成功实现多种害虫的性别分离。我们对性比失衡分离策略、雌性条件性致死分离策略和可视化性别分离策略在双翅目害虫中的研究进展进行了综述,重点评估了这些方法在雄虫大规模饲养和释放的应用潜力,以期在更完善的性别分离技术支持下为害虫防治研究取得更多突破性进展。     

中国冠潜蛾科一新记录属及一新记录种

记述我国冠潜蛾科Tischeriidae 1新记录属:绔冠潜蛾属Coptotriche Walsingham,1890及1新记录种:日本绔冠潜蛾Coptotriche japoniella Puplesis ＆ Digkus,2003;并给出了成虫、潜痕和雌雄生殖器照片.所有标本材料均保存在湖南农业大学昆虫研究所昆虫标本馆.     

中国冠潜蛾科-新记录属及一新记录种

记述我国冠潜蛾科Tischeriidae 1新记录属：绔冠潜蛾属Coptotriche Walsingham,1890及1新记录种：日本绔冠潜蛾Coptotriche japoniella Puplesis＆Diskus,2003;并给出了成虫、潜痕和雌雄生殖器照片。所有标本材料均保存在湖南农业大学昆虫研究所昆虫标本馆。     

双翅目害虫性别分离技术的研究进展及展望

在过去的几十年中,昆虫不育技术(sterile insect technique, SIT)已被用于防治农业害虫和人类健康相关的病媒害虫。相较于传统的农药控制策略,昆虫不育技术具有物种特异性和环境友好型等特点。通过释放不育雄虫的昆虫不育技术的主要障碍是在大规模饲养阶段将雄性与雌性分离,从而提高这些防治方法的成本效率,并防止释放携带和传播疾病的雌性群体。目前大多数针对双翅目害虫的遗传防治策略没有进行性别分离,少数害虫性别分离方法是基于蛹的大小或者雌雄蛹羽化时间差异进行人工识别和机械识别分离。双翅目昆虫性别决定及分化分子机制多种多样,其性别决定主要信号差异巨大,其多种性别决定基因已用于性别分离系统的开发。性比失衡性别分离策略通过破坏性别决定途径关键基因的表达获得雄性偏向后代,雌性条件性致死分离策略利用性别决定关键基因的雌雄选择性剪接差异实现性别分离,这两种性别分离策略目前正在害虫不育防治中接受大规模饲养应用评估,而基于双翅目昆虫雌雄性二态和基因标记发展的可视化性别分离策略也已成功实现多种害虫的性别分离。我们对性比失衡分离策略、雌性条件性致死分离策略和可视化性别分离策略在双翅目害虫中的研究进展进行了综述,重点评估了这些方法在雄虫大规模饲养和释放的应用潜力,以期在更完善的性别分离技术支持下为害虫防治研究取得更多突破性进展。     

褐飞虱长翅型和短翅型雌雄成虫体内磁性物质定位和定量检测

【目的】地磁定向是昆虫远距离迁飞定向的重要机制之一。本研究以迁飞性害虫褐飞虱Nilaparvata lugens长翅型和短翅型雌雄成虫为研究对象,系统开展虫体内磁性物质定量研究。【方法】本研究利用MPMS-7型超导量子磁强计检测褐飞虱长翅型和短翅型雌雄成虫体内的磁性物质,并将经普鲁士蓝染色后的虫体超薄石蜡切片于JEM-2100型透射电子显微镜下观察磁性物质的分布状况,最后利用原子发射光谱法对虫体内的磁性物质进行定量分析与比较。【结果】超导量子磁强计检测发现,仅在褐飞虱长翅型和短翅型雌雄成虫腹部的磁滞曲线有明显闭合现象,证明该部位存在磁性物质;经透射电镜观察发现,普鲁士蓝沉淀主要呈点簇状存在于虫体腹部,证明该部位存在铁磁性物质;通过等离子发射光谱检测发现,同一性别长翅型成虫体内铁离子含量显著高于短翅型成虫,且相同翅型雄成虫体内铁离子含量显著高于雌成虫。【结论】褐飞虱长翅型和短翅型雌雄成虫腹部普遍存在铁磁性物质,且不同翅型和性别间磁性物质含量差异显著。     

二型花柱植物金荞麦的繁殖生态学研究

通过野外实验观察和人工控制套袋等方法,从金养麦的花部基本特征、开花动态、花粉胚珠比(P/O)、花粉活力、柱头可授性、杂交指数、套袋实验及访花昆虫等方面对其繁殖生态学进行了研究.结果显示:(1)金荞麦在同一居群中同时具有长柱型(L-型)和短柱型(S-型)两种花型,短花柱花直径(7.25±0.11 mm)显著大于长花柱花直径(6.79±0.11 mm),长花柱花的柱头和花药高分别为3.39±0.04 mm和1.80±0.02 mm,短花柱花的柱头和花药高则分别为1.89±0.04 mm和3.19±0.06 rnm,表现出互补式雌雄异位的花部特征.(2)金荞麦8～10月开花,单花序的花期为15～23 d,单花的花期为1～3 d,开花进程中,内轮雄蕊先散粉,外轮雄蕊后散粉;S-型花的花粉活力高于L型花的花粉活力,但其单花花粉量低于L-型花,显示了两种花型的自我调控机制.(3)套袋实验表明,金荞麦自花自交不亲和,但具有型内和型间亲和性,L型和S-型花的P/O值分别为810±40.48和526.5±42.24,表明其繁育系统为兼性异交,需要传粉者,但L-型花更倾向异交.(4)金荞麦的主要访花昆虫为膜翅目(Hymenoptera)、双翅目(Diptera)、鳞翅目(Lepidoptera)、半翅目(Hemiptera)和蜻蜒目(Odonata) 19个科37种昆虫,其中,两种花型拥有12种共同的访花昆虫,L-型花访花昆虫14种,S-型花访花昆虫35种,表明S-型花对昆虫具有更强的吸引力.研究表明,金荞麦是典型的二型花柱植物,虽然具有严格的自交不亲和性,但显示一定的型内亲和性.     

Sexual shape dimorphism accelerated by male–male competition,but not prevented by sex-indiscriminate parental care in dung beetles (Scarabaeidae)

Dimorphic sexual differences in shape and body size are called sexual dimorphism and sexual size dimorphism, respectively. The degrees of both dimorphisms are considered to increase with sexual selection, represented by male–male competition. However, the degrees of the two dimorphisms often differ within a species. In some dung beetles, typical sexual shape dimorphisms are seen in male horns and other exaggerated traits, although sexual size dimorphism looks rare. We hypothesized that the evolution of this sexual shape dimorphism without sexual size dimorphism is caused by male–male competition and their crucial and sex-indiscriminate provisioning behaviors, in which parents provide the equivalent size of brood ball with each of both sons and daughters indiscriminately. As a result of individual-based model simulations, we show that parents evolve to provide each of sons and daughters with the optimal amount of resource for a son when parents do not distinguish the sex of offspring and males compete for mates. This result explains why crucial and sex-indiscriminate parental provisioning does not prevent the evolution of sexual shape dimorphism. The model result was supported by empirical data of Scarabaeidae beetles. In some dung beetles, sexual size dimorphism is absent, compared with significant sexual size dimorphism in other horned beetles, although both groups exhibit similar degrees of sexual shape dimorphism in male horns and other exaggerated traits.     

QUANTITATIVE GENETICS OF SEXUAL DIMORPHISM IN HUMAN BODY SIZE

A classical data set is used to predict the effect of selection on sexual dimorphism and on the population means of three characters—stature, span, and cubit—in humans. Given selection of equal intensity, the population means of stature and of cubit should respond more than 60 times as fast as dimorphism in these characters. The population mean of span should also respond far more rapidly than dimorphism, but no numerical estimate of the ratio of these rates was possible. These results imply that sexual dimorphism in these characters can evolve only very slowly. Consequently, hypotheses about the causes of sexual dimorphism cannot be tested by comparing the dimorphism of different human societies. It has been suggested that primate sexual dimorphism may be an allometric response to selection for larger body size. We show that such selection can indeed generate sexual dimorphism, but that this effect is too weak to account for the observed relationship between dimorphism and body size in primates.     

Carnivory maintains cranial dimorphism between males and females: Evidence for niche divergence in extant Musteloidea

The evolution and maintenance of sexual dimorphism has long been attributed to sexual selection. Niche divergence, however, serves as an alternative but rarely tested selective pressure also hypothesized to drive phenotypic disparity between males and females. We reconstructed ancestral social systems and diet and used Ornstein–Uhlenbeck (OU) modeling approaches to test whether niche divergence is stronger than sexual selection in driving the evolution of sexual dimorphism in cranial size and bite force across extant Musteloidea. We found that multipeak OU models favored different dietary regimes over social behavior and that the greatest degree of cranial size and bite force dimorphism were found in terrestrial carnivores. Because competition for terrestrial vertebrate prey is greater than other dietary groups, increased cranial size and bite force dimorphism reduces dietary competition between the sexes. In contrast, neither dietary regime nor social system influenced the evolution of sexual dimorphism in cranial shape. Furthermore, we found that the evolution of sexual dimorphism in bite force is influenced by the evolution of sexual dimorphism in cranial size rather than cranial shape. Overall, our results highlight niche divergence as an important mechanism that maintains the evolution of sexual dimorphism in musteloids.     

Sex-limited expression of ornamental feathers in birds

Extravagant secondary sexual characters show sexual size dimorphismin some species but are completely sex limited in others. Sexualornamentation has been hypothesized to benefit mainly malesthrough sexual selection, but the costs of secondary sexualcharacters initially would be experienced by both sexes. Theevolution of sexual size dimorphism of ornaments and, eventually, the complete sex-limited expression of these characters, willdepend on the effects of sexual and natural selection on thetwo sexes. A phylogenetic analysis controlling for similaritiesdue to common ancestry of 60 independent evolutionary originsof feather ornamentation in birds was used to investigate ecologicalfactors correlated with sexual size dimorphism and sex-limited expression of secondary sexual characters. When the size ofan ornament is large relative to body size, the trait willbe particularly costly for females, resulting in selectionfor increased sexual size dimorphism of the ornament. Indeed,sexual size dimorphism of ornaments was positively related to the relative size of male ornaments but was unrelated torelative size of female ornaments. Species with polygynousand lekking mating systems with little or no male parentalcare (in particular nest building and incubation) demonstratedsex-limited expression of ornaments as compared to monogamous species. Species with no food provisioning of offspring by themale showed a trend for increased sexual size dimorphism ofornaments. Therefore, large natural selection costs duringreproduction imposed by the expression of secondary sexualcharacters are related to the evolution of sexual size dimorphismof ornaments and eventually their complete loss from females.     

Sex-specific ecomorphological variation and the evolution of sexual dimorphism in dwarf chameleons (Bradypodion spp.)

Natural selection can influence the evolution of sexual dimorphism through selection for sex-specific ecomorphological adaptations. The role of natural selection in the evolution of sexual dimorphism, however, has received much less attention than that of sexual selection. We examined the relationship between habitat structure and both male and female morphology, and sexual dimorphism in size and shape, across 21 populations of dwarf chameleon (genus Bradypodion). Morphological variation in dwarf chameleons was strongly associated with quantitative, multivariate aspects of habitat structure and, in most cases, relationships were congruent between the sexes. However, we also found consistent relationships between habitat and sexual dimorphism. These resulted from both differences in magnitude of ecomorphological relationships that were otherwise congruent between the sexes, as well as in sex-specific ecomorphological adaptations. Our study provides evidence that natural selection plays an important role in the evolution of sexual dimorphism.     

Sexual dimorphism in weight among the primates: The relative impact of allometry and sexual selection

In this paper, we examine allometric and sexual-selection explanations for interspecific differences in the amount of sexual dimorphism among 60 primate species. Based on evidence provided by statistical analyses, we reject Leutenegger and Cheverud’s [(1982). Int. J. Primatol.3:387-402] claim that body size alone is the major factor in the evolution of sexual dimorphism. The alternative proposed here is that sexual selection due to differences in the reproductive potential of males and females is the primary cause of sexual dimorphism. In addition, we propose that the overall size of a species determines whether the dimorphism will be expressed as size dimorphism,rather than in some other form.     

A PHYLOGENETIC PERSPECTIVE ON THE EVOLUTION OF SEXUAL DICHROMATISM IN TANAGERS (THRAUPIDAE): THE ROLE OF FEMALE VERSUS MALE PLUMAGE

The evolution of sexual dichromatism in tanagers (family Thraupidae) was studied from a phylogenetic perspective using a molecular-based phylogeny. Mapping patterns of sexual dimorphism in plumage onto the phylogeny reveals that changes in female plumage occur more frequently than changes in male plumage. Possible explanations for this pattern include sexual selection acting on female plumage and natural selection for background matching. The results of this study and other recent phylogenetic and comparative studies suggest that factors affecting female plumage are important in shaping patterns of sexual dimorphism.     

HOW TO COMPENSATE FOR COSTLY SEXUALLY SELECTED TAILS: THE ORIGIN OF SEXUALLY DIMORPHIC WINGS IN LONG-TAILED BIRDS

Recent work on birds suggests that certain morphological differences between the sexes may have evolved as an indirect consequence of sexual selection because they offset the cost of bearing extravagant ornaments used for fighting or mate attraction. For example, long-tailed male sunbirds and widowbirds also have longer wings than females, perhaps to compensate for the aerodynamic costs of tail elaboration. We used comparative data from 57 species to investigate whether this link between sexual dimorphism in wing and tail length is widespread among long-tailed birds. We found that within long-tailed families, variation in the extent of tail dimorphism was associated with corresponding variation in wing dimorphism. One nonfunctional explanation of this result is simply that the growth of wings and tails is controlled by a common developmental mechanism, such that long-tailed individuals inevitably grow long wings as well. However, this hypothesis cannot account for a second pattern in our data set: as predicted by aerodynamic theory, we found that, comparing across long-tailed families, sexual dimorphism in wing length varied with tail shape as well as with sex differences in tail length. Thus, wing dimorphism was generally greater in species with aerodynamically costly graduated tails than in birds with cheaper, streamer-shaped tails. This result was not caused by confounding phylogenetic effects, because it persisted when phylogeny was controlled for, using an independent comparisons method. Our findings therefore confirm that certain aspects of sexual dimorphism may sometimes have evolved through selection for traits that reduce the costs of elaborate sexually selected characters. We suggest that future work aimed at understanding sexual selection by investigating patterns of sexual dimorphism should attempt to differentiate between the direct and indirect consequences of sexual selection.     

The geography of sex‐specific selection,local adaptation,and sexual dimorphism

Local adaptation and sexual dimorphism are iconic evolutionary scenarios of intraspecific adaptive differentiation in the face of gene flow. Although theory has traditionally considered local adaptation and sexual dimorphism as conceptually distinct processes, emerging data suggest that they often act concurrently during evolutionary diversification. Here, I merge theories of local adaptation in space and sex‐specific adaptation over time, and show that their confluence yields several new predictions about the roles of context‐specific selection, migration, and genetic correlations, in adaptive diversification. I specifically revisit two influential predictions from classical studies of clinal adaptation and sexual dimorphism: (1) that local adaptation should decrease with distance from the species’ range center and (2) that opposing directional selection between the sexes (sexual antagonism) should inevitably accompany the evolution of sexual dimorphism. I show that both predictions can break down under clinally varying selection. First, the geography of local adaptation can be sexually dimorphic, with locations of relatively high local adaptation differing profoundly between the sexes. Second, the intensity of sexual antagonism varies across the species’ range, with subpopulations near the range center representing hotspots for antagonistic selection. The results highlight the context‐dependent roles of migration versus sexual conflict as primary constraints to adaptive diversification.     

Canine dimorphism

Canine dimorphism in many primates is exaggerated, with males possessing enormous, sharp canines that project far beyond the occlusal plane of the other teeth and females having smaller, less projecting canines. Ever since Darwin,¹ canine dimorphism generally has been attributed to sexual selection. However, recent analyses suggest that the evolution of canine dimorphism is complex and that the sexual selection hypothesis is only part of the story.