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61.
We studied the effect of capture and handling on free-living red-billed choughs Pyrrhocorax pyrrhocorax . We analysed the association between bird behavioural response and individual health, breeding status, sex, and age. Active responses (aggression towards the ringer, screaming) were more common in the breeding period, and in individuals with a high heterophils to lymphocytes ratio, indicating poor physiological condition and/or high chronic stress. Adults were more aggressive than juveniles and yearlings, and females were more aggressive than males. Sex, age, and condition differences were also recorded in the spectrotemporal output of distress calls. Birds with a screaming/active response appeared to be more stress-susceptible than passive and silent individuals, and this response was stronger during the energy demanding period of reproduction. The results obtained suggest that the response of the red-billed chough during capture might primarily reflect stress-susceptibility, although a number of potential alternative explanations are discussed.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 846–855.  相似文献   
62.
Herein we describe a new rhynchocephalian taxon from the Middle Jurassic of Patagonia, Argentina, representing the first Jurassic record of the group in South America. The new taxon, consisting of a complete dentary, is ascribed to Sphenodontia based on the presence of a deep and wide Meckelian groove, long posterior process, well‐developed coronoid process, and acrodont teeth showing dental regionalization including successional, alternate hatchling, and additional series. This allocation is reinforced by a phylogenetic analysis that places the new taxon in a basal position within a clade of sphenodontians that excludes Diphydontosaurus and Planocephalosaurus. Additionally, the new taxon clusters within a Gondwanan clade with the Indian Godavarisaurus from the Jurassic Kota Formation, sharing the presence of recurved and relatively large posterior successional teeth that are ribbed and bear a peculiar anterolingual groove. This sister‐group relationship is intriguing from a palaeobiogeographical viewpoint, as it suggests some degree of endemism during the initial stages of the breakup of Pangaea. We also discuss the ontogenetic stage of the new taxon and provide insights on the evolution of successional dentition in rhynchocephalians. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 342–360.  相似文献   
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1. This study deals with the distribution of euglenoid morphospecies along the length of the Lower Paraná River floodplain. Six sites located in the Paraná River, Estevez stream and Montiel shallow lake were surveyed monthly from May 1995 to April 1996. 2. Eighty‐eight infrageneric taxa were registered though the total density percentage of euglenoids seldom exceeded 15% of total phytoplankton. The increasing species richness towards the lake is mostly the result of a high contribution of species of Trachelomonas and naked infrageneric taxa of Euglena, Lepocinclis and Phacus, while the distribution of Strombomonas species along the transect is fairly constant. 3. The richness of euglenoid morphospecies follows a pattern opposite to that found for the entire phytoplankton community. The distribution of euglenoids differs among the three habitats defined in this study: river, stream, shallow lake. These differences depend on the hydraulic condition of each habitat, as revealed by canonical correspondence analysis. 4. The degree of association with each type of aquatic habitat varied among the species and differed between water phases. Strombomonas fluviatilis was equally constant along the length of the ecotone, while S. girardiana and S. scabra were particularly associated with the Paraná River and P. longicauda, L. truncata, T. hispida and T. similis with the lake. 5. The flood pulse establishes a clear pattern both in species richness and abundance of euglenoids. The number of species recorded during high water was more than twice that recorded during low water.  相似文献   
65.
There is considerable controversy concerning the origin of Iberian populations of the Mediterranean chameleon, Chamaeleo chamaeleon . Current opinion dictates that Spanish populations result from introductions during the 18th and 19th centuries, with subsequent translocations from the original populations to other parts of Spain. The Portugese population in the Algarve is believed to have been introduced from Africa or Spain during the 1920s. However, Holocene remains of chameleons suggest that the Malaga population at least could have a much older origin. Analysis of sequences from the mitochondrial 16S ribosomal RNA gene of samples from the Iberian Peninsula and North Africa revealed a double origin for the Iberian population. The Mediterranean Iberian (Malaga) population is closely related to Mediterranean North African populations, with Atlantic Iberian populations more closely related to populations of the Atlantic coast of North Africa. The overall genetic differentiation and diversity observed was very low, preventing precise dating of the colonization events. However this low level of differentiation is not consistent with Plio-Pleistocene colonization, the assumed timing for a natural colonization event and suggests that chameleons were probably introduced twice by man in the recent past. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 75 , 1–7.  相似文献   
66.
The immune system has high costs of maintenance and production and expression of immune function should be dependent on the condition of the individual. The fitness cost that parasites impose on hosts may then be reflected in the investment that hosts make in immunity. Little is known about sources and consequences of intra- and interspecific variation in the presence and size of organs of the immune system in relation to ectoparasitism. Variation in the presence and size of the bursa of Fabricius and spleen size was measured to assess potential relationships between immune defence, nutritional condition and ectoparasites in the Magpie Pica pica. We found three species of lice (Mallophaga), two species of louse flies (Hippoboscidae), and the larvae of a tick (Ixodidae) infecting magpies. Age explained a significant proportion of variation in prevalence and number of parasite species, first-year birds being more parasitized than adults. Spleen size increased with nutritional condition, and the level of ectoparasitism negatively affected nutritional condition. Only one species of lice (Philopterus picae) was involved; the negative effect of this species on nutritional condition was more pronounced in males than females. These results are consistent with the hypotheses of condition-dependent investment in the immune system and sexual differences in susceptibility to parasite effects. Ectoparasites may thus play a role in modulating the relationship between condition and immune defence. We also found evidence for an interaction between the bursa and the spleen. Magpies with bursa had larger spleens than those where it had atrophied. This interaction did not affect ectoparasitism or nutritional condition.  相似文献   
67.
Microsatellite or simple sequence repeat markers derived from expressed sequence tags (ESTs) provide genetic markers within potentially functional genes, which could be very useful for breeding programs. To date, the development of microsatellite markers in the genus Fragaria has focused mainly on Fragaria vesca. However, most of the interests of breeding programs relate to specific characteristics of cultivated strawberry. Here, we describe a set of 10 EST‐derived microsatellites from Fragaria × ananassa. These markers showed high levels of polymorphism within strawberry cultivars and among different Fragaria species, indicating their potential for genetic studies not only on strawberry but also in other species within the genus.  相似文献   
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人工林碳汇潜力新概念及应用   总被引:5,自引:0,他引:5  
定量确定森林碳汇潜力有助于科学地评估森林对碳汇的潜在贡献及制定实现这种潜力所需要的经营管理措施。目前,国内外有关森林碳汇潜力缺乏统一的概念及计量方法。在综述国内外有关固碳潜力概念的基础上,引入时间动态构架和可持续性的概念,提出了针对人工林的固碳潜力概念并利用FORECAST模型以杉木人工林为例阐明此概念的实际意义与应用。  相似文献   
70.
1. The consequences of symbiont transmission strategies are better understood than their adaptive causes. 2. Feather mites are permanent ectosymbionts of birds assumed to be transmitted mainly vertically from parents to offspring. The transmission of Proctophyllodes doleophyes Gaud (Astigmata, Proctophyllodidae) was studied in two European populations of pied flycatchers, Ficedula hypoleuca Pallas (Passeriformes, Muscicapidae). 3. The vertical transmission of this mite species is demonstrated here with an acaricide experiment. This study also compared (for two distant populations during 4 years) patterns in reductions in mite intensity in adult birds, from egg incubation to chick‐rearing periods, with the predictions of three hypotheses on how host survival prospects and mite intraspecific competition might drive feather mites' transmission strategy. 4. The results are in agreement with previous studies and show that feather mites transmit massively from parents to chicks. 5. The magnitude of the transmission was closer to that predicted by the hypothesis based on intraspecific competition, while a bet‐hedging strategy is also partially supported.  相似文献   
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