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A life-history perspective on strategic mating effort in male scorpionflies   总被引:3,自引:1,他引:2  
In species with high male mating effort, there is a trade-offbetween mating effort spent in a current mating and resourcesleft for future matings. Consequently, to maximize their reproductivesuccess, males have to invest strategically, saving resourcesin matings with low reproductive gain for future, more valuablematings. However, as males age, the expected future reproductivesuccess constantly declines. Thus, the importance of resource rationing may drastically change during a lifetime. Males ofthe scorpionfly Panorpa cognata offer females a costly nuptialgift before copulation, which functions as male mating effort.Resources for the production of these salivary masses are severelylimited for males in poor condition. We found that males investedmore in copulations with high-quality females than in copulationswith low-quality females. However, males ceased to discriminateas they became older. Old males, with a relative small numberof expected future matings, did not invest differentially incopulations with high- versus low-quality females. In copulationswith low-quality females, males invested more in late thanin initial matings, whereas in matings with high-quality females,time of mating had no influence on mating effort. These resultsimply that males adaptively change their resource allocationstrategy during the course of the season. Initial matings seemto be characterized by male prudence; in later matings, malesseem to adopt a more opportunistic mating strategy.  相似文献
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Previous studies of the phenologies and the different microclimatic patterns of the distribution of the scorpionflies Panorpa communis L. and Panorpa vulgaris Imhoff and Labram 1836 showed different phenological strategies. In P. communis , a species foraging at shadowy and cool places only, a majority of 90% of the individuals are univoltine; however, approximately 10% of the offspring of the first annual generation are bivoltine. This proportion remained unchanged in the Freiburg population over 8 years. Differently, all individuals of P. vulgaris foraging equally frequent at sunny and warm as at shadowy and cool places are bivoltine. The proximate cause of bivoltinism in both species is a heritable variation of different ‘day length thresholds’ triggering diapause‐free development if natural day length exceeds these thresholds. As selection favours maximal temporal exploitation of food availability it remains obscure why in P. communis the number of diapause‐free developing individuals does not increase continuously from year to year although this phenotype reproduces twice a year. Therefore, in the present paper, we focus on the following main questions. Does the competitive inferiority of P. communis in the presence of P. vulgaris at the temperature regime of the late summer function as a mechanism maintaining the majority of individuals of P. communis univoltine, by dramatically reducing the fitness of the bivoltine ones? As a long‐term evolutionary change in the frequency of bivoltine individuals in P. communis solely depends on the lifetime reproductive success of the females, we here consider the influence of interspecific competition and temperature conditions on the reproductive success of the females of P. communis only. Five lines of evidence suggest that the mechanism of maintaining univoltinism in P. communis is primarily because of differences in the ability of each species to exploit dead arthropod resources: (1) these species show complete diet overlap; (2) dead arthropods are limiting resources for both species of scorpionflies as indicated by positive demographic effects with increased food availability; (3) in competition with P. vulgaris at high temperatures, P. communis is competitively inferior in the ability to detect and exploit dead arthropods; (4) this reduced resource acquisition of female P. communis translates into significant reductions in the survivorship, body condition, fecundity and lifetime reproductive success; (5) exploitation competition does account for these negative demographic effects on second‐generation females of P. communis more than interference competition.  相似文献
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There are very few investigations of cold hardiness in native Australian insects, and no such studies on insects from Tasmania. The Apteropanorpidae is a family of wingless Mecoptera endemic to Tasmania, comprising four described species that can be active in winter. In this study, we used infrared video thermography to investigate the physiological and behavioural responses of Apteropanorpa tasmanica to fast (0.3 degrees Cmin(-1)) and slow (0.03 degrees Cmin(-1)) rates of temperature reduction down to -10 degrees C. No adults survived cooling to -10 degrees C at either cooling rate. Mean supercooling points (SCPs) from fast cooling were -7.0 and -4.6 degrees C in 2002 and 2003, respectively. Ice nucleation always began in the abdomen, however, the position of nucleation within the abdomen varied between individuals. There was no relationship between SCP and body length, and no significant difference in SCPs between males and females. Stress-induced fast walking began when insects reached approximately -1.5 degrees C. Cooling rate did not affect the SCP or the temperature at which the behavioural stress response began. Adults survived for only short periods of time in the supercooled state; however they survived in the laboratory for up to 60 days at 4 degrees C, indicating their longevity at more favourable temperatures. Members of the Apteropanorpidae are adapted to the relatively warm, maritime climate currently influencing Tasmania.  相似文献
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Two new species and a new genus of scorpionflies of the family Kaltanidae, Pseudochorista occidentalis sp. nov. and Kamochorista novokshonovi gen. et sp. nov. (Mecoptera: Kaltanidae), are described from the Urzhumian of Udmurtia (Chepanikha locality). This is the first record of kaltanids on the Russian Platform.  相似文献
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长翅目昆虫在地史纪录上可以追溯到早二叠纪,是全变态昆虫中最原始的种类之一.截至目前,29篇关于中国长翅目昆虫化石分类的论著发表,共描述我国长翅目昆虫化石11科28属51种,这些化石分布于从三叠纪到白垩纪的不同地层中.本文通过图表提供了我国已发现的长翅目化石名录并介绍了其分布和年代,回顾了我国长翅目昆虫化石的研究进展,指出了一些分类存在的问题,简要慨述了长翅目中一些科的起源与演化以及长翅目与其它全变态昆虫的关系.我国长翅目化石种类丰富,但在基础分类、系统演化方面还缺乏系统的研究,因而许多工作甚至最基础的分类工作亟待开展.  相似文献
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Five new scorpionfly species of the genus Dicerapanorpa Zhong and Hua, 2013 are described and illustrated from Yunnan Province, China. Dicerapanorpa macula sp. n. can be readily recognized by all branches of paramere parallel, basal and mesal branches extending well beyond basal process of gonostylus in male, and posterior arm of medigynium short and stout in female. Dicerapanorpa deqenensis sp. n. is characterized by basal branch of paramere as long as lateral branch and ventral valve of aedeagus nearly reaching apex of gonocoxite in male, and medigynium with paired auricular lateral processes in female. Dicerapanorpa tanae sp. n. is unique by genital bulb broad and spherical, basal branch of paramere short, and lateral branches curved convergently and parallel apically in male, and main plate of medigynium rounded in female. Dicerapanorpa tenuis sp. n. is distinguishable by hypovalve with largely expanded and inward curved apex and all branches of paramere reaching or exceeding apex of gonocoxite in male, and medigynium slender in female. Dicerapanorpa zhongdianensis sp. n. is characterized by basal branches of paramere parallel and mesal branches curved convergently in male, and main plate of medigynium subtriangular with a pair of auricular lateral processes in female. The species number of Dicerapanorpa is increased to thirteen.LSID: www.zoobank.org/urn:lsid:zoobank.org:pub:A4490511-C475-4C5B-9E89-4BF4EBAA2137  相似文献
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A new genus of Panorpidae, Megapanorpa gen. nov. , is erected for five new species, Megapanorpa grandis sp. nov. (type species), M. absens sp. nov. , M. gaokaii sp. nov. , M. jiangorum sp. nov. and M. wanghongjiani sp. nov. This genus is similar to Cerapanorpa Gao et al., 2016 in a single anal horn on the sixth tergum of male, but can be differentiated from the latter by the following characters: the seventh abdominal segment of male is constricted and stalk‐like at base, the subgenital plate of female with a pair of lateral plates, and the medigynium of female with a concealed axis. Keys to genera of Panorpidae and species of Megapanorpa gen. nov. are presented. The morphology and function of anal horns in different genera and species have been discussed.  相似文献
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