No modularity at ventral level in the horse skull

Morphological integration and modularity are concepts that refer to the covariation level between the components of a structure. Morphological modules are independent subsets of highly correlated traits. The horse skull has been studied as a whole functional structure for decades, but the integrative approach towards quantitative examination of modules is scarce. We report here the first evaluation of cranial modularity in the horse at basal level. For this, we studied the modularity hypothesis for splanchnocranium and basicranium modules in the horse, two phenotipic regions under local influence by soft-tissue–hard-tissue interfaces. Using geometric morphometrics to capture the shape and location, we examined both modules in a sample of 23 dry skulls belonging to Pyrenean Horse Breed using 57 two-dimensional cranial landmarks. Modules were compared through partial least squares analyses and Escoufier (RV) coefficient. We tested whether the integration (measured by Escoufier RV coefficient) of splanchnocranium and basicranium strength modules and their covariation pattern (as analysed by partial least squares analysis) subordinate and express similar integration results. A clear modularity was observed. The lack of disproportions in the skulls of domestic horse breeds (compared to dog and cat breeds, for instance) might be an expression of the lack of single modules to evolve. On the other side, integration might have a positive impact on survival as long as the selection pressure is along the trajectory of integrated variation.     

几何形态学方法区分短吻鲾地方种群的研究

运用传统形态测量方法和地标点方法对广东阳江和湛江两个短吻鲾的形态特征进行了分析。传统测量方法的主成分分析的前两个主成分(76.29%)能明显地区分出两个种群。相对扭曲主成分分析前3个主成分(64.03%)也能明显地区分出两个种群,但效果差于传统方法的主成分分析。网格变形图显示,两地短吻鲾的形态差异主要表现在头部。地标点法避免了传统的多变量形态测量方法的信息冗余、包含的形状信息不够完整等问题,并能够重建图形,突出局部的形变,能够直观地比较出研究对象之间的细微差别。研究亮点:地标点法是国外最新发展出并被广泛使用的形态测量方法,该方法以地标点的坐标来表示生物的形状信息,再通过旋转与重叠,用网格图形和相对扭曲分析样本间的形状差异。本文在国内首次使用该方法有效地区分了短吻鲾的不同地方种群。     

两种耳石分析法在鲚属种间和种群间识别效果的比较研究

采用耳石传统形态测量法和傅里叶形态分析法,对281尾2龄长江凤鲚(Coilia mystus)和刀鲚(C.nasus)个体的矢耳石形态学作了分析,结果表明,采用传统的耳石形态测量法对凤鲚与刀鲚种间的正判率达90.9%,但2个刀鲚生态型种群之间的判别成功率仅为76.9%。而运用傅里叶耳石形态分析法,凤鲚和刀鲚物种间的识别率高达100%,2个刀鲚生态型间的识别率也提高至86.8%。可见,两种耳石形态分析法对鲚属种间的识别效果均很好,但对种群分析而言,傅里叶形态分析法可以取得更好的识别效果。     

小盾片几何形态特征在10种鳃金龟分类中的应用

为探讨小盾片几何形态特征对金龟子分类鉴定的可行性和可靠性,以金龟子小盾片的几何形态测量特征为依据,对10种鳃金龟进行分类识别,利用TpsDig2软件在10种金龟子各20个样本的小盾片上,分别提取8个标记点,再利用PAST软件进行普氏叠加和薄板样条分析,消除大小、方向等非形状因素的影响后,得到小盾片8标记点形状的扭曲图像,最后利用SPSS 22.0进行判别分析。结果表明:对10种鳃金龟小盾片8个标记点坐标数据进行普氏叠加和薄板样条分析后,得到标记点位置折线图和扭曲图像,可直观看出10种鳃金龟小盾片形态差异主要发生在标记点2和6处;利用小盾片8个标记点坐标数据形成的几何形态特征进行判别分析,原始判别和交叉判别正确率均高达99.0%。因此,利用小盾片的几何形态特征可以对10种鳃金龟进行准确识别。     

Genetic and morphological divergences between wild and captive‐bred populations of Salmo trutta abanticus

Salmo trutta abanticus is a non‐anadromous trout species native to Lake Abant and Seven Lakes in Turkey. A restocking programme by captive breeding was initiated in 1999 to support S. trutta abanticus population. Reared 2‐year‐old juveniles from randomly caught wild parental individuals in Maçka breeding farm were introduced into Lake Abant. We aimed to compare genetic and morphological divergences between wild‐ and captive‐bred populations using seven microsatellite loci and geometric morphometric measurements. A significant genetic and morphological divergences were detected between all population in F_st and canonical variate analysis based on geometric morphometric with 10 homolog landmark. Eighty‐six microsatellites alleles were recorded across loci. Number of private alleles, observed alleles and observed heterozygosity are statistically significant higher in Maçka captive‐bred population than Lake Abant and Seven Lakes populations. Of 42 tests, three departures from Hardy–Weinberg equilibrium were detected in all populations after Bonferroni correction. Two pairs of loci (Ssa85 – Str73 and Str73‐Str543) in Maçka, one pairs of loci (Ssa85‐Str73) in Abant and two pairs of loci (Ssa85‐Str60 and Str73‐Str543) in Seven Lakes populations show linkage disequilibrium. Population structure analysed with Structure software showed three genetic groups (?K = 3) in our studied populations. Relatedness estimates show higher mean relatedness values (r = 0.220 ± 0.230) for Maçka captive‐breed population than wild populations of Abant Lake and Seven Lakes (r = 0.140 ± 0.210 and r = 0.170 ± 0.200 respectively).     

褐牙鲆(♀)×犬齿牙鲆( ♂)杂交子一代胚胎发育及仔稚鱼形态学观察

杂交是目前水产育种中应用最为广泛、最有成效的育种途径,为了选育一个能够促进中国海水鱼类养殖业发展,改善目前养殖褐牙鲆发病严重的现状的牙鲆类养殖新品种,对褐牙鲆(Paralichthys olivaceus)(♀)×犬齿牙鲆(P.dentatus)(♂)的杂交进行了研究。在Nikon MS800解剖镜下对褐牙鲆(♀)×犬齿牙鲆(♂)人工杂交子一代的胚胎及胚后发育进行观察,并使用Nikon数码相机拍摄其发育特征,描述了各发育时期的发育时序和形态特征。杂交子一代胚胎发育可分为卵裂前期、卵裂期、囊胚期、原肠期、神经胚期、器官发生期、尾芽期、肌肉效应期、脱膜孵化期共9个时期,除克氏泡出现时期以及胚体开始扭动时期具有相对特异性外,胚胎发育过程与褐牙鲆相比无显著差异。在水温(16.5±0.5)℃,盐度32~33的条件下,受精卵历时67 h完成孵化。(19±0.5)℃水温下,仔鱼3 d以前营内源性营养(卵黄囊仔鱼),3 d开口摄食营外源性营养(前弯曲期仔鱼),20 d左右进入变态期(弯曲期仔鱼),40 d后基本完成变态进入稚鱼阶段,生活方式由浮游转为底栖生活,50 d左右全身被鳞。同时观察了自胚胎发育时期至幼鱼期体表色素的分布及形态变化过程,描述了仔鱼变态期冠状鳍条、眼位置和尾部的发育、变化过程。早期生活史无鳔器官发生。     

Beech leaf disease symptoms caused by newly recognized nematode subspecies Litylenchus crenatae mccannii (Anguinata) described from Fagus grandifolia in North America

Symptoms of beech leaf disease (BLD), first reported in Ohio in 2012, include interveinal greening, thickening and often chlorosis in leaves, canopy thinning and mortality. Nematodes from diseased leaves of American beech (Fagus grandifolia) sent by the Ohio Department of Agriculture to the USDA, Beltsville, MD in autumn 2017 were identified as the first recorded North American population of Litylenchus crenatae (Nematology, 21, 2019, 5), originally described from Japan. This and other populations from Ohio, Pennsylvania and the neighbouring province of Ontario, Canada showed some differences in morphometric averages among females compared to the Japanese population. Ribosomal DNA marker sequences were nearly identical to the population from Japan. A sequence for the COI marker was also generated, although it was not available from the Japanese population. The nematode was not encountered in Fagus crenata (its host in Japan) living among nematode‐infested Fagus grandifolia in the Holden Arboretum, nor has L. crenatae been reported in American beech in Japan. The morphological and host range differences in North American populations are nomenclaturally distinguished as L. crenatae mccannii ssp. n. from the population in Japan. Low‐temperature scanning electron microscopy (LT‐SEM) demonstrated five lip annules and a highly flexible cuticle. Females, juveniles and eggs were imaged within buds with a Hirox Digital microscope and an LT‐SEM. Nematodes swarmed to the tips of freshly cut beech buds, but explants could not be maintained. Inoculation of fresh nematodes from infested leaves or buds to buds or leaves of F. grandifolia seedlings resulted in BLD leaf symptoms. Injuring dormant buds prior to nematode application, in fall or spring, promoted the most reliable symptom expression. The biogeography and physiology of anguinid nematode leaf galling, and potential co‐factors and transmission are discussed.     

利用几何形态测量学方法分析唐鱼群体的形态变异

唐鱼是华南地区小型亚科鱼类的典型代表,国家Ⅱ级保护水生野生动物。本研究利用基于地标点的几何形态测量学方法分析了唐鱼8个野生种群和2个养殖群体的形态变异,旨在从形态学的角度了解唐鱼不同种群间的分化程度,为唐鱼保护策略的制定提供科学依据。新鲜标本冰冻麻醉后随即置于95%酒精中固定,用Nikon D-800单反相机拍照获得固定标本的标准图像。利用tps系列软件提取地标点坐标值,进行相对扭曲主成分分析、网格变形分析和判别分析来解释唐鱼的形态变异。相对扭曲主成分分析结果显示,第1、2、3主成分分别解释了总变异的48.20%、23.12%和14.83%,降维效果较好。其中,Ⅱ型地标点12、13、14和15贡献较大,四者合计贡献率达71.28%,反映出唐鱼群体的形态变异主要表现在眼径大小和头部形态。逐步判别分析和交互验证分析的总体判别正确率分别为97.6%和92.0%,能有效识别唐鱼群体。研究结果还揭示了唐鱼野生种群和养殖群体之间存在显著的形态差异。基于上述结果以及唐鱼呈点状分布的事实,建议将唐鱼的7个野生种群(越南种群除外)各自作为单独的保护单元进行重点保护,同时建议禁止在野外放流养殖群体。     

Stocking density and its influence on shape of Senegalese sole adults

Morphological changes in Senegalese sole adults (Solea senegalensis Kaup, 1858) reared at two stocking density conditions (low stocking density, 60% of bottom occupation and high stocking density, 180% of bottom occupation) were investigated using geometric morphometrics. Canonical variate analysis on weight matrix scores, including the uniform component (W′), at the end of the experiment revealed differences in body shape between experimental groups. The low density group presented a similar change pattern as that of the high density group but was less intense. Differences were discussed in terms of the effect of a high stocking density on the shape of soles which were very close to commercialization. Results did not indicate a significant size-related shape, likely due to fish age. Our results provide the first promising look at environment-related shape changes in reared sole.     

基于几何形态测量的西北太平洋日本鲭的个体生长规律

为探究西北太平洋海域日本鲭(Scomber japonicus)的个体生长规律,利用基于地标点的几何形态测量方法对2021-2022年“淞航号”在西北太平洋海域采集的210尾日本鲭样本进行形态学分析。结果发现不同体长组的日本鲭的外部形态存在显著差异(P<0.01)。主成分分析和多元回归分析均显示,体长组越小的个体,其分区更为明显,三个不同体长组间的分区位置存在重叠,不同体长组的具有相同的生长模式,日本鲭形态生长速率随体长的增加而逐渐减小。薄板样条变形网格结果表明,体长越小的日本鲭个体,其腹部,尾部越小,日本鲭的外部形态随着体长的改变而发生变化。结论认为,西北太平洋日本鲭生长形态随着体长的增加而逐渐发生改变。