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1.
Aim  We analysed the geographical distributions of species of Buprestidae (Coleoptera) in Mexico by means of a panbiogeographical analysis, in order to identify their main distributional patterns and test the complex nature of the Mexican Transition Zone, located between the Nearctic and Neotropical regions.
Location  Mexico.
Methods  The geographical distributions of 228 species belonging to 33 genera of Buprestidae were analysed. Localities of the buprestid species were represented on maps and their individual tracks were drawn. Based on a comparison of the individual tracks, generalized tracks were detected and mapped. Nodes were identified as the areas where generalized tracks converged.
Results  Thirteen generalized tracks were obtained: one was restricted to the Mexican Transition Zone and five to the Neotropical region (Antillean and Mesoamerican dominions), a further two occurred in both the Nearctic region (Continental Nearctic dominion) and the Mexican Transition Zone, and a further five in both the Neotropical region (Mesoamerican dominion) and the Mexican Transition Zone. Seven nodes were identified at the intersections of the generalized tracks – in the Mesoamerican dominion (Mexican Pacific Coast, Mexican Gulf and Chiapas biogeographical provinces) and the Mexican Transition Zone (Trans-Mexican Volcanic Belt, Balsas Basin and Sierra Madre Oriental biogeographical provinces).
Main conclusions  We conclude that the geographical distribution of Buprestidae is mainly Neotropical, corresponding to the Mesoamerican dominion and the Antillean dominion of the Neotropical region, and the Mexican Transition Zone. Most of the generalized tracks and nodes correspond to the Mexican Transition Zone, thus confirming its complex nature. We suggest that the nodes we have identified could be particularly important areas to choose for conservation prioritization.  相似文献   
2.
3.
Panbiogeography represents the spatial congruence among species distributions by means of generalized tracks. Some critics have suggested the method fails to objectively evaluate congruence, being neither repeatable nor falsifiable. The MartiTracks software was proposed to address spatial congruence using geometric properties as a counterpoint to the manual procedures so far employed in generalized track obtainment. To evaluate whether MartiTracks is a reliable alternative to the congruence problem in the quantitative panbiogeographic approach, we tested the software parameters with three analysis schemes under two real datasets. Then, we proceeded to a comparison of the results to those produced from Parsimony Analysis of Endemicity (PAE) and Clique Analysis, two quantitative methods which are based in predefined biogeographic areas or in the employment of grid cells. For PAE we used both analytical units, while Clique Analysis was restricted to grid cells. Through this, we aimed to comparatively evaluate the criteria of spatial congruence in different approaches. For each dataset and method, significantly different tracks resulted, highlighting the disparate congruence criteria among panbiogeographic approaches. Despite PAE ending up as the most reliable of the tools tested, it is still far from solving panbiogeographic congruence. The main focus of this paper, MartiTracks, is indeed a tool that makes minimum spanning tree construction a repeatable and easy-to-visualize process, but stumbles upon its obscure procedures of generalized track obtainment, congruence criteria, subjective parameter definition, the unclear implications of employing said parameters, and dubious results. Our results suggest that the subjectivity of the parameter setup process substantially influences the results, biasing them to the user-desired level of congruence. That the software produces fast and easy-to-visualize results does not make it a definitive solution to the problem of quantitative panbiogeographic approaches.  相似文献   
4.
张倩  康斌 《动物学研究》2013,34(4):429-436
为探讨团头鲂幼鱼(Megalobrama amblycephala)游泳行为对水流的响应规律,该文通过特制鱼类游泳行为测定装置,测定了团头鲂幼鱼在25℃,0、0.1、0.2、0.3、0.4m/s流速条件下的游速、游距、转角、至中心点的距离及游泳轨迹。结果表明:随着流速的增大,个体游速、游距及转角值均相应增大。0、0.1及0.2m/s流速组间的游速、游距及转角差异均不显著(P>0.05),但显著小于0.3和0.4m/s组别,且0.3和0.4m/s流速组之间差异均不显著(P>0.05);整个时间段内,个体至中心点的距离随流速增大并未呈现明显规律性,各流速间差异不显著(P>0.05),游速与游距呈显著线性正相关,而与转角呈显著线性负相关,与至中心点的距离则无相关性;游泳轨迹随水流增大趋向复杂化。  相似文献   
5.
狗獾秋季对生境的选择——以黑龙江省方正林业局为例   总被引:3,自引:0,他引:3  
在黑龙江省方正林业局新风林场利用痕迹检验法和洞穴辨别法对狗獾秋季生境选择进行研究。通过在选定的15个林班的23条样线进行调查,共测定了106个利用样方和106个对照样方的19种生态因子。结果表明,狗獾秋季利用样方和对照样方在优势乔木、坡向、灌木密度和灌木高度4种生态因子上差异极显著(P0.001),在灌木距离上差异显著(P0.05),其余的生态因子无显著差异(P0.05),相对于对照样方而言,狗獾秋季更偏爱选择位于阳坡,优势乔木为紫椴和黄菠萝,灌木密度大、高度高、距离近的生境。在典则系数的直方图上可以看出秋季狗獾的利用样方与对照样方存在一定的重叠,但是Wilk’sλ值显示秋季狗獾的利用样方与对照样方具有较高的差异性(Wilk’sλ=0.507,χ2=141.524,df=3,P0.001),较高比例的(84.0%)正确判别率也支持了这种差异性。逐步判别分析表明在区分秋季狗獾的利用样方与对照样方方面有3个生态因子发挥作用,依照贡献值的大小依次为:郁闭度、灌木密度和植被盖度。  相似文献   
6.
Nie X  Deng CX  Wang Q  Jiao K 《Developmental biology》2008,316(2):417-430
TGFβ/BMP signaling pathways are essential for normal development of neural crest cells (NCCs). Smad4 encodes the only common Smad protein in mammals, which is a critical nuclear mediator of TGFβ/BMP signaling. In this work, we sought to investigate the roles of Smad4 for development of NCCs. To overcome the early embryonic lethality of Smad4 null mice, we specifically disrupted Smad4 in NCCs using a Cre/loxP system. The mutant mice died at mid-gestation with defects in facial primordia, pharyngeal arches, outflow tract and cardiac ventricles. Further examination revealed that mutant embryos displayed severe molecular defects starting from E9.5. Expression of multiple genes, including Msx1, 2, Ap-2α, Pax3, and Sox9, which play critical roles for NCC development, was downregulated by NCC disruption of Smad4. Moreover, increased cell death was observed in pharyngeal arches from E10.5. However, the cell proliferation rate in these areas was not substantially altered. Taken together, these findings provide compelling genetic evidence that Smad4-mediated activities of TGFβ/BMP signals are essential for appropriate NCC development.  相似文献   
7.
ABSTRACT We designed a novel approach to determining extent of distribution and area of occupancy for wolverines (Gulo gulo) by using aerial surveys of tracks in snow and hierarchical spatial modeling. In 2005 we used a small, fixed-wing aircraft with pilot and one observer to search 575 of 588 survey units for wolverine tracks in approximately 60,000 km2 of boreal forest in northwestern Ontario, Canada. We used sinuous flight paths to scan open areas in the forest in the 100-km2 survey units. We detected tracks in 138 (24%) of the 575 sampled units. There was strong evidence of occurrence (probability of occurrence >0.80) in 30% of the 588 survey units, weak evidence of occurrence (0.50–0.80) in 12%, weak evidence of absence (0.20–0.50) in 15%, and strong evidence of absence (< 0.20) in 43%. Wolverine range comprised 59% of the study area and area of occupancy was 33,400 km2. With information on probability of occurrence and core areas of occupation for wolverines in our study area, resource managers and others can examine factors that influence wolverine distribution patterns and use this information to formulate best management practices that will maintain wolverines on the landscape in the face of increasing resource development. Comparing future survey results with those of our 2005 survey will provide an objective way to assess the efficacy of management practices.  相似文献   
8.
The final second of the landing approach of black bean aphids, Aphis fabae, was analysed in three dimensions using video techniques. A yellow landing platform was placed upwind or downwind from aphids aggregating under a ceiling light in a laboratory wind tunnel with 10, 20, 30, 40 or 50 cm s–1 wind speeds, and up-tunnel or down-tunnel in still air. As individual aphids flew to the platform, body orientation (assessed by direct observation) was predominantly into-wind whether the initial flight direction to the landing platform was upwind or downwind. A greater proportion showed into-wind body orientation as wind speed increased. Flight track parameters which differed significantly between wind speeds were the track length, linear start to finish distance, linearity index, horizontal ground speed, speed vertical to the ground, vertical turning rate, and horizontal turning rate. The position of the landing platform was important for track length, linear start to finish distance, horizontal ground speed, three-dimensional turning rate, horizontal turning rate, vertical turning rate, and sinuosity. As wind speed increased above 30 cm s–1 the ground speed became more consistent and indicated considerable variation in air speed to adjust for ground speed. For the majority of aphids there was a strong preference (88%) for into-wind landings with initial upwind directed flight, while for downwind flights a significant number (55%) of insects reversed initial flight direction and landed into-wind. Field recorded landings showed that 66% of aphids landed into-wind and there was a mean bearing to the wind of 71 ± 42°, a similar finding to wind-tunnel studies.  相似文献   
9.
长爪沙鼠寄生蚤指数和气象因子关系的研究   总被引:3,自引:2,他引:1  
李仲来  陈德 《昆虫学报》1999,42(3):284-290
根据内蒙古自治区土默特平原1983~1985年长爪沙鼠 Meriones unguiculatus巢蚤、体蚤、洞干蚤指数和6项气象资料进行分析,得到如下结果。① 共获蚤11种, 其中秃病蚤蒙冀亚种Nosopsyllus laeviceps kuzenkovi(67.50%)是优势种, 二齿新蚤Neopsylla bidentatiformis(22.65%)为次优势种。② 3种蚤指数的均值差异显著(P<0.0001)。③ 体蚤与洞干蚤指数相关显著(P<0.05), 模型为(洞干蚤指数)=0.0049+0.0248(体蚤指数), 巢蚤与体蚤、巢蚤与洞干蚤指数的相关不显著(P>0.25)。④ 沙鼠密度与3种蚤指数的相关均不显著(P>0.10)。⑤ 在巢蚤中,月温度是影响巢秃病蚤唯一的气象因子(P<0.05)。⑥ 分别求出鼠体的秃病蚤和同形客蚤指名亚种Xenopsylla conformis conformis与气象因子的最优回归子集(P<0.003、P<0.05), 洞干的秃病蚤和二齿新蚤与气象因子的最优回归子集(P<0.0007、P<0.01), 月蒸发量是影响秃病蚤的最重要因子。⑦ 春季与冬季、夏季与冬季巢蚤指数差异显著(P<0.05); 春季与冬季、夏季与冬季体蚤指数差异显著(P<0.05); 春季与冬季、夏季与秋季、夏季与冬季洞干蚤指数差异显著(P<0.05)。  相似文献   
10.
The feeding of spittlebug nymphs (Philaenus spumarius) from mature xylem vessels was studied by optical and cryo-analytical scanning electron microscopy. Feeding did not produce xylem embolisms and vessels remained liquid-filled during the day. Saliva secreted by the insect forms a hardened lining (salivary sheath) between the stylet bundle and the plant tissues. This sheath is continuous through the hole made by the stylets as they enter a vessel, and it extends into the vessel and along its periphery beyond the breach. The sheath is heterogeneous, with a thin outer layer adjoining the plant tissues and a thicker layer that contacts the stylet bundle. Both layers give positive histochemical reactions for proteins and, in fresh tissues, contain a red, strongly autofluorescent pigment, possibly condensed tannin derived from the plant (which is lost during tissue preparation), and other phenyl propanoid compounds, which are retained and which may produce the intense reaction of the periodic-acid-Schiff's-positive inner layer. It is concluded that the salivary sheath allows the insects to feed from functioning vessels without embolizing them or losing xylem fluid to the surrounding tissues. These findings and others in the entomological literature indicate low daytime tensions in the xylem conduits of the host plants.  相似文献   
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