排序方式: 共有44条查询结果,搜索用时 62 毫秒
1.
Robby Stoks 《Ecological Entomology》2001,26(2):181-187
1. There is ongoing controversy about whether biased sex ratios in diploid insect populations are real or an artefact caused by different behaviours and/or different catchability of the sexes. This was tested by monitoring two field and three semi-natural populations of the damselfly Lestes sponsa. 2. Capture–mark–recapture data showed that population size estimates were about twice as large for males as for females at both field sites. Independent estimates of the sex ratios based on total numbers of males and females captured supported the male bias. 3. Males had higher recapture probabilities than females due to longer times between successive visits in females. Because the same pattern was found in the semi-natural populations, the longer intervals in females are no artefact due to their lower detectability. 4. Theoretical models show that the strong temporary emigration of females tends, if anything, to overestimate female population sizes and that the heterogeneity of recapture probabilities observed in males tends to underestimate male population sizes. Hence, behavioural differences between the sexes do not cause an artificially male-biased sex ratio. 5. Spatial data show that operational sex ratios are male biased at the pond but become female biased in the plots further away from the shoreline; however because of the decrease in densities away from the shoreline, this does not result in a global even sex ratio. 6. Spatial data, temporary emigration patterns, and independent estimates suggest strongly that the male-biased sex ratios in mature damselfly populations are real. 相似文献
2.
Arnold Åbro 《Journal of invertebrate pathology》1982,39(3):373-381
Arrenurus larvae, ectoparasitic on zygopteran imagoes, attach to the host's cuticle and tear it to obtain the host's tissue fluids. Within the host's epidermis, each larval mite produces a feeding device, the stylostome, a narrow gelatinous resilient blind sac. Heavy mite infestation brings about several wounds in close proximity, accompanied by loss of more or less extensive areas of the epidermis. Despite wound repair by congregating hemocytes, local lack of epidermis seems to enfeeble the host, presumably owing to desiccation. Heavily mite-loaded zygopterans have lost the typical agility and are easily caught. A mite-induced mortality seems to exist in zygopteran populations; the infestation contributes to reduced longevity. The study of formation and decline of the arrenurid stylostome in zygopterans renders it possible to trace cellular defence reactions under natural conditions. Most stylostomes seem to thwart the ability of the host to recognize them as foreign bodies. The host's defence appears as a two-step reaction: (1) initial hemolymph clotting and deposition of melanin associated with aggregating hemocytes at the penetration site, (2) occasional subsequent melanization and cellular encapsulation of the stylostome. 相似文献
3.
The first fossil representative of the jewel damselflies (Calopterygoidea: Chlorocyphidae), a family of large, prominent, and often brilliantly colored Old World tropical Zygoptera, is described and figured. Chlorocypha cordasevae n. sp. was recovered from the Late Miocene (Early Pannonian, Serravalian to Tortonian, c.11 Ma) locality of Paldau, in the Styrian Basin, Austria. The fossil seems to be related to the African genus Chlorocypha Fraser, and within a larger group of African genera also including Stenocypha Dijkstra, Africocypha Pinhey, and Platycypha Fraser, and collectively set apart from southern Asiatic genera. The discovery of a central European species of Chlorocypha as recently as the Late Miocene reveals a much wider range to the family than its generally disjunctive modern distribution, demonstrating a Neogene contraction to their range, likely in connection with climatic cooling, drying, and developing seasonality. Modern chlorocyphids live under warm, humid climates, and the presence of C. cordasevae in the Pannonian fauna of Paldau further corroborates such a subtropical paleoclimate for the locality at that time. 相似文献
4.
Conditional male mating strategies have been studied extensivelyin relation to male attributes, such as size and resource-holdingpotential, but few studies have considered the effects of environmentalheterogeneity on the use of alternative mating tactics. In somesystems, environmental heterogeneity may be the key to understandingthe evolution and maintenance of such polyphenisms. I examinedthe influence of the physical environment on the use of alternativetactics by the damselfly Protoneura amatoria. Male P. amatoriareversibly use 2 tactics to gain matings: 1) sit and wait inthe canopy for passing females or 2) hover over the water andattempt to grab females that are ovipositing in floating debris.Observations in 3 streams indicated that the use of the hoveringtactic was greater under high-light than low-light conditionsand at higher densities of ovipositing females. The densityof ovipositing females was correlated with both the light conditionsand the availability of oviposition substrate, indicating thatphysical factors exert indirect as well as direct influenceson tactic use. Experimental manipulations showed that both malesand females responded directly to light conditions and suggestedthat males responded directly to the density of ovipositingfemales. These results can be explained largely in terms ofthe cues and constraints inherent in different light environments.Thus, the conditional mating strategy of P. amatoria appearsto have evolved in response to, and been maintained by, fine-scalevariation in the physical environment. These findings are discussedin relation to flight dynamics and predation risk. 相似文献
5.
6.
The objective of this study was to estimate Argia vivida (Odonata: Coenagrionidae) populations, identify breeding habitat, and investigate movement of adults within Banff National
Park, Alberta, Canada, during the summer of 2003. Mark-recapture techniques and standardized dip-net surveys were used to
monitor Argia vivida at various life stages. A reproductive index identified which sites Argia vivida recognized as suitable breeding habitat, and exuvia surveys confirmed breeding sites. The basic structure of emergent and
surrounding vegetation was measured to investigate the importance of available ovipositing or roosting sites and the condition
of the matrix habitat. Data was recorded for Amphiagrion abbreviatum and Ischnura cervula (both Odonata: Coenagrionidae) to determine if these spring-associated damselflies were successfully breeding within Banff
National Park. Comparisons were made between the highly protected Middle Springs and the heavily altered Cave & Basin Springs.
Additional surveys at the Vermilion Lake cool spring and Middle Springs Bog investigated their use as breeding habitat for
Amphiagrion abbreviatum and Argia vivida, respectively. Results suggest the ecological value of thermal springs extends beyond their origin to outflows and downstream
pools. Conservation of Argia vivida must recognize the value of unobstructed thermal outflows, and consider the condition of the forested habitat surrounding
springs with regard to its potential use as nocturnal roosts and dispersal corridors. Amphiagrion abbreviatum was confirmed breeding within Banff National Park, while no sign of breeding activity was recorded for Ischnura cervula. 相似文献
7.
北京地区均翅亚目昆虫的生态分布 总被引:2,自引:0,他引:2
调查发现北京地区现分布蜻蜓目均翅亚目昆虫 3科 1 0种 ,其中科的蓝纹与二色异痣为优势种 ,分布最为广泛 ,通过主成分分析 ,湿地内的浮水层植物盖度、挺水层植物盖度、周围植被盖度及沉水层植物盖度是影响它们分布的最主要生态因子 ,各因子的贡献率分别为 3 0 49,2 4 1 4,1 7 45和1 5 2 6%。色科黑色和透顶单脉色主要分布于北京西南部地区及北部山区水流较快、水体较浅、污染度较小的水域。长叶异痣、七条和白扇主要分布在河流和水库湖泊的边缘地带 ,数量相对较少。烟翅绿色、红痣绿色及白狭扇仅在山区发现 ,分布范围较为狭窄。 相似文献
8.
9.
The new damselfly genus and species Valerea multicellulata is described from the Paleocene of Menat (France), a Lagerstatte with many fossil insects, plants and vertebrates with high paleontological value. Aquatic insects are very scarce in this outcrop, this damselfly being the fourth described Odonata. Its closest modern relatives belong to the Amphipterygidae or the Devadattidae, families with very narrow tropical extant distributions. This new fossil allows us to confirm the tropical affinities of the odonatan fauna of the Menat paleolake communities. It also shows that the amphipterygids were clearly more widespread during the Paleogene than today, probably in relation to the worldwide warm and equable climate in the Paleocene.
http://zoobank.org/urn:lsid:zoobank.org:act:3F631097-DE0B-40FA8227-9C12F55DBAB4 相似文献
10.
Coding characters from different life stages for phylogenetic reconstruction: a case study on dragonfly adults and larvae,including a description of the larval head anatomy of Epiophlebia superstes (Odonata: Epiophlebiidae) 下载免费PDF全文
Alexander Blanke Sebastian Büsse Ryuichiro Machida 《Zoological Journal of the Linnean Society》2015,174(4):718-732
The exclusive use of characters coding for specific life stages may bias tree reconstruction. If characters from several life stages are coded, the type of coding becomes important. Here, we simulate the influence on tree reconstruction of morphological characters of Odonata larvae incorporated into a data matrix based on the adult body under different coding schemes. For testing purposes, our analysis is focused on a well‐supported hypothesis: the relationships of the suborders Zygoptera, ‘Anisozygoptera’, and Anisoptera. We studied the cephalic morphology of Epiophlebia, a key taxon among Odonata, and compared it with representatives of Zygoptera and Anisoptera in order to complement the data matrix. Odonate larvae are characterized by a peculiar morphology, such as the specific head form, mouthpart configuration, ridge configuration, cephalic musculature, and leg and gill morphology. Four coding strategies were used to incorporate the larval data: artificial coding (AC), treating larvae as independent terminal taxa; non‐multistate coding (NMC), preferring the adult life stage; multistate coding (MC); and coding larval and adult characters separately (SC) within the same taxon. As expected, larvae are ‘monophyletic’ in the AC strategy, but with anisopteran and zygopteran larvae as sister groups. Excluding larvae in the NMC approach leads to strong support for both monophyletic Odonata and Epiprocta, whereas MC erodes phylogenetic signal completely. This is an obvious result of the larval morphology leading to many multistate characters. SC results in the strongest support for Odonata, and Epiprocta receives the same support as with NMC. Our results show the deleterious effects of larval morphology on tree reconstruction when multistate coding is applied. Coding larval characters separately is still the best approach in a phylogenetic framework. © 2015 The Linnean Society of London 相似文献