个体发育对黄海南部金乌贼角质颚形态的影响

为了探究个体发育和食性对金乌贼角质颚形态的影响。实验采用几何形态测量学地标点法对2018年11月—2019年3月在黄海南部采集的金乌贼角质颚进行形态分析,共对138对金乌贼的上、下颚分别定义了27个地标点进行分析。结果显示,①不同发育阶段的金乌贼上、下颚的大小、形态及异速生长模式均存在显著差异,并且不同性别的上颚形态存在显著差异。②未成熟期的金乌贼角质颚的喙部较弯曲和尖锐,亚成熟期的角质颚头盖和翼部变宽,喙部也较尖锐,而成熟期的角质颚喙部短钝,侧壁较尖长,下颚翼部宽大。研究表明,不同发育阶段角质颚的发育机制可能是为更好地适应摄食对象变更,满足摄食需求做出的响应。这些与个体生长发育和摄食习性相关的表型可塑性反映了金乌贼角质颚的生长规律和金乌贼对食物资源的适应性利用。本研究通过分析金乌贼角质颚形态的生长变化,完善了金乌贼的基础生物学信息,为金乌贼资源的合理利用提供一定的科学依据。     

Comparing geometric morphometrics and outline fitting methods to monitor fish shape variability of Diplodus puntazzo (Teleostea: Sparidae)

The definition of a remote system in the monitoring of fin fish shape variability relies on the appropriate shape analysis tools. In this paper, different methods are proposed and compared. Growth trajectories, computed using geometric morphometrics, allow the pattern of size-related shape change and visualize growth allometry to be analyse. Geometric morphometrics is used to describe shape change in three samples (507 5100 days after hatching) of 119 individuals of the Sparid Diplodus puntazzo. The results are potentially interesting but the method still relies on the manual detection of homologous landmarks (coordinates of points located unambiguously on each specimen’s profile or structure) which are basic for such analysis. In an attempt to proceed towards the remote estimation and the automation of data collection, two alternative approaches are tested. In particular, Elliptic Fourier analysis and Bezier function were applied to the same samples, and results compared with geometric morphometrics. Fourier analysis’ growth curves are very similar to geometric morphometrics’ ones and allows for an appropriate visualisation of global shape changes. At the same time, Fourier methods can be applied to remotely and automatically detected profiles. This method is thus considered as the best candidate in the context of automated fish shape monitoring. The Bezier method performed poorly, both in terms of statistical output and shape visualization.     

入侵种麦穗鱼的形态特征分析

研究不同生境条件下入侵种的形态差异是了解生物入侵的重要手段。运用多变量形态度量学和框架结构形态学方法,测量了采自四川南充、石棉、茂县和西昌共4个不同栖息地的94尾麦穗鱼(Pseudorasbora parva)标本,在双筒解剖镜下检视,采用电子数显游标卡尺测量了侧线鳞、侧线上鳞、侧线下鳞以及背鳍、胸鳍、腹鳍、臀鳍的分枝鳍条共7个可数性状。应用多变量形态度量学方法,选择18个框架结构性状和16个常规性状进行主成分分析。结果表明,3个主成分的累计贡献率达到76.59%,4个不同地点的标本聚在一起没有分开,表明入侵种麦穗鱼各居群间的形态没有显著差异。结合文献资料分析了麦穗鱼入侵的原因,指出了在进行经济鱼类引种过程中,应针对麦穗鱼制定有效地管理措施,实行早期的监测和预警系统,防止麦穗鱼的卵、苗种和幼鱼等人为侵入;已发现的麦穗鱼应该及时处理,避免其在引入地进一步扩散;对于已经在引入地建立了自然种群的麦穗鱼,应该根据生物学原理(如生理、生态因子的耐受性、食性、繁殖特性、寄生虫感染等)进行综合治理,使其对土著鱼类的危害处在可控范围之内。     

文蛤属2种贝类多变量形态分析及日本文蛤的物种有效性

为探讨日本文蛤与中国文蛤属2种贝类的形态差异及日本文蛤的物种有效性,采用多变量形态度量,结合传统分类方法,获得日本文蛤和中国大陆文蛤属2种贝类8个形态比例性状,并做单因素方差分析、聚类分析、主成分分析、判别分析及Mantel检验。结果表明,(1) 单因子方差分析显示,日本文蛤与中国大陆文蛤属2种贝类,在8个比例性状中存在着5~8个显著差异(P<0.05);(2) 聚类分析表明,6个文蛤地理种群距离相近,且呈现南北分别聚为一类,而日本文蛤与长乐丽文蛤相近;(3) 主成分分析构建了3个主成分,其贡献率分别为34.88%、18.61%、16.89%,累积贡献率为70.38%,三维主成分散布图进一步表明日本文蛤与丽文蛤均独立于文蛤不同地理种群重叠区之外;(4) 判别分析构建了8个判别函数,判别准确率P₁为39.09%~100%,P₂为47.06%~100%,日本文蛤与中国大陆文蛤属2种贝类的综合判别率为70.60%,其中日本文蛤判别准确率为100%,丽文蛤判别准确率高于91.67%;(5) Mantel检验结果表明,各种群间的地理距离与欧氏距离之间存在显著相关性(r=0.623 7, P<0.01)。研究认为,日本文蛤属于丽文蛤,与长乐丽文蛤属于同一种不同地理种群;根据MAYR等提出的75%规则,8个比例性状中有5个性状大于1.28,两个丽文蛤群体已达到亚种水平。     

Preliminary evidences of colour differences in European sea bass reared under organic protocols

Product diversification, among which organic farming, is an important issue in modern aquaculture activities. Discriminating organic vs. conventional products is complex, but appearance may help in tracing different batches of produce. To test this fact, sea basses were fed a commercial or an organic diet, and fishes of each different group were photographed before and during the experiment. Body landmarks were digitized on each colour-calibrated (using the TPS-3D algorithm) image; on the basis of landmarks configuration, the RGB matrices were warped using a geometric morphometrics procedure. The calibrated colour matrix of each warped individual (195 × 135,225) was analyzed with a 50–50 MANOVA, followed by a partial least squares discriminant analysis. Finally, a cluster analysis on the diet/time groups was performed. Growth and changes in condition factor over time are not dependent on the rearing method. Colour (as represented by the pixel vector) does depend on time and on rearing method, based on the MANOVA method used. Standard length and condition factor were not good predictors of colour. The partial least square discriminant analysis was highly effective in detecting colour differences on the basis of the fish diet. The 9-group dendrogram showed that the wild sample and the organic fish cluster together. The head, darker in fishes raised conventionally, is the part showing the greatest difference; the longer the life spent under the 2 regimens, the stronger the differences. In conclusion, these preliminary results demonstrate that a colorimetric analysis is able to distinguish 2 batches of fishes fed different diets in different environmental conditions and – in the present instance – to certify the organically grown sea basses.     

东海常见鲳属鱼类的形态差异及系统进化关系探讨

应用多变量形态度量学方法研究了鲳属中常见鱼类银鲳、翎鲳和中国鲳的形态差异,同时对3种鲳鱼线粒体DNA 16S rRNA基因序列差异进行了分析,并根据3种鲳鱼的形态和分子数据对其系统进化关系进行了探讨.聚类分析表明,银鲳和翎鲳形态较为相似,而与中国鲳形态差异较大.判别分析表明,3种鲳鱼形态上存在着明显差异,利用4个形态参...     

Lack of trophic polymorphism despite substantial genetic differentiation in sympatric brown trout (Salmo trutta) populations

Sympatric populations occur in many freshwater fish species; such populations are typically detected through morphological distinctions that are often coupled to food niche and genetic separations. In salmonids, trophic and genetically separate sympatric populations have been reported in landlocked Arctic char, whitefish and brown trout. In Arctic char and brown trout rare cases of sympatric, genetically distinct populations have been detected based on genetic data alone, with no apparent morphological differences, that is “cryptic” structuring. It remains unknown whether such cryptic, sympatric structuring can be coupled to food niche separation. Here, we perform an extensive screening for trophic divergence of two genetically divergent, seemingly cryptic, sympatric brown trout populations documented to remain in stable sympatry over several decades in two interconnected, tiny mountain lakes in a nature reserve in central Sweden. We investigate body shape, body length, gill raker metrics, breeding status and diet (stomach content analysis and stable isotopes) in these populations. We find small significant differences for body shape, body size and breeding status, and no evidence of food niche separation between these two populations. In contrast, fish in the two lakes differed in body shape, diet, and nitrogen and carbon isotope signatures despite no genetic difference between lakes. These genetically divergent populations apparently coexist using the same food resources and showing the same adaptive plasticity to the local food niches of the two separate lakes. Such observations have not been reported previously but may be more common than recognised as genetic screenings are necessary to detect the structures.     

Inter- and intraspecific morphometric variation and characterization of Phytophthora isolates from cocoa

Difficulties in the accurate identification of the Phytophthora species responsible for black pod disease of cocoa continue to hamper effective disease control. A re-evaluation of morphological characters ( Brasier & Griffin, 1979 ) and a detailed morphometric analysis of 161 Phytophthora isolates largely associated with black pod disease of cocoa from 17 countries worldwide have shown considerable inter- and intraspecific variation. Stable and more reliable parameters for the identification of the species responsible for the disease have been determined. Colony characteristics such as pattern and growth rate on V8 agar are reasonably characteristic for the cocoa Phytophthora species, and can be used to make preliminary identification to species level. Significant sporangial character variation was found within isolates of species from the same and different sources, highlighting the difficulties in making accurate identification on the basis of raw morphological data. Pedicel length was found to be the most consistent species-linked sporangial characteristic. Cluster plots of length/breadth ratios of sporangia versus reciprocals of sporangial pedicel length clearly separated all isolates into distinct species groups ( P. capsici , P. citrophthora , P. palmivora and P. megakarya ) and can be used reliably to identify accurately those pathogens involved in black pod disease outbreaks.