An early fossil remora (Echeneoidea) reveals the evolutionary assembly of the adhesion disc

The adhesion disc of living remoras (Echeneoidea: Echeneidae) represents one of the most remarkable structural innovations within fishes. Although homology between the spinous dorsal fin of generalized acanthomorph fishes and the remora adhesion disc is widely accepted, the sequence of evolutionary—rather than developmental—transformations leading from one to the other has remained unclear. Here, we show that the early remora †Opisthomyzon (Echeneoidea: †Opisthomyzonidae), from the early Oligocene (Rupelian) of Switzerland, is a stem-group echeneid and provides unique insights into the evolutionary assembly of the unusual body plan characteristic of all living remoras. The adhesion disc of †Opisthomyzon retains ancestral features found in the spiny dorsal fins of remora outgroups, and corroborates developmental interpretations of the homology of individual skeletal components of the disc. †Opisthomyzon indicates that the adhesion disc originated in a postcranial position, and that other specializations (including the origin of pectination, subdivision of median fin spines into paired lamellae, increase in segment count and migration to a supracranial position) took place later in the evolutionary history of remoras. This phylogenetic sequence of transformation finds some parallels in the order of ontogenetic changes to the disc documented for living remoras.     

A review of the pelvic girdle of acanthomorph fishes, with comments on hypotheses of acanthomorph intrarelationships

The anatomy of the pelvic girdle of acanthomorph fishes is reviewed. Derived morphological features of the pelvic complex are identified and discussed as evidence for the recognition of a monophyletic Acanthomorpha, Acanthopterygii and Percomorpha. Within the Percomorpha, evidence is presented to support the grouping of the Holocentridae with the remaining percomorph assemblage. An additional sub-grouping of "higher percomorphs" is also proposed.     

Do key innovations unlock diversification? A case-study on the morphological and ecological impact of pharyngognathy in acanthomorph fishes

Key innovations may allow lineages access to new resources and facilitate the invasion of new adaptive zones, potentially influencing diversification patterns. Many studies have focused on the impact of key innovations on speciation rates, but far less is known about how they influence phenotypic rates and patterns of ecomorphological diversification. We use the repeated evolution of pharyngognathy within acanthomorph fishes, a commonly cited key innovation, as a case study to explore the predictions of key innovation theory. Specifically, we investigate whether transitions to pharyngognathy led to shifts in the rate of phenotypic evolution, as well as shifts and/or expansion in the occupation of morphological and dietary space, using a dataset of 8 morphological traits measured across 3,853 species of Acanthomorpha. Analyzing the 6 evolutionarily independent pharyngognathous clades together, we found no evidence to support pharyngognathy as a key innovation; however, comparisons between individual pharyngognathous lineages and their sister clades did reveal some consistent patterns. In morphospace, most pharyngognathous clades cluster in areas that correspond to deeper-bodied morphologies relative to their sister clades, while occupying greater areas in dietary space that reflects a more diversified diet. Additionally, both Cichlidae and Labridae exhibited higher univariate rates of phenotypic evolution compared with their closest relatives. However, few of these results were exceptional relative to our null models. Our results suggest that transitions to pharyngognathy may only be advantageous when combined with additional ecological or intrinsic factors, illustrating the importance of accounting for lineage-specific effects when testing key innovation hypotheses. Moreover, the challenges we experienced formulating informative comparisons, despite the ideal evolutionary scenario of multiple independent evolutionary origins of pharyngognathous clades, illustrates the complexities involved in quantifying the impact of key innovations. Given the issues of lineage specific effects and rate heterogeneity at macroevolutionary scales we observed, we suggest a reassessment of the expected impacts of key innovations may be warranted.     

结构植物学在中国的五十年发展

结构植物学由植物解剖学发展而来,是植物学的一个重要分支学科.本文根据其近代的发展,分别就植物发育解剖学向植物发育生物学的发展、植物比较解剖学向植物系统发育生物学的发展,以及环境生态结构植物学三个主要部分简要介绍了50年来在我国的发展,并对它们的发展趋势进行了预测.     

结构植物学在中国的五十年发展

结构植物学由植物解剖学发展而来 ,是植物学的一个重要分支学科。本文根据其近代的发展 ,分别就植物发育解剖学向植物发育生物学的发展、植物比较解剖学向植物系统发育生物学的发展 ,以及环境生态结构植物学三个主要部分简要介绍了 5 0年来在我国的发展 ,并对它们的发展趋势进行了预测     

含笑属叶片的比较解剖学研究

对中国含笑属 ( Michelia) 1 8种 (包括观光木 1 ) ) ,1变种的叶片进行了比较解剖学研究 ,结果表明 :( 1 )含笑属植物的叶片均有明显的栅栏组织和海绵组织之分 (除石碌含笑和观光木外 ) ,但二者的厚度及它们在叶肉中的所占的比例在组间、种间有一定的差别 ;( 2 )有些种类叶片的上表皮有下皮 ,有些则无 ,少数种类 (石碌含笑 )上、下表皮皆有下皮 ;( 3)表皮毛的有无及表皮毛的细胞个数有一定的种间差别 ;( 4 )叶表皮角质层的厚薄程度在种间有一定的差别 ;( 5 )油细胞在含笑属植物叶片整个叶肉中普遍存在 (除含笑只在栅栏组织中有分布 ) ,但其分布密度在种间有较大的差异。通过对含笑属植物叶片结构的比较观察 ,旨在探讨该属间的系统演化关系 ,为分组、分种提供解剖学方面的实验证据     

五种大戟属植物nrDNA的ITS序列分析及其叶的比较解剖学研究

运用PCR直接测序法和石蜡切片法,测定5种安徽产大戟属植物的nrDNA的内转录间隔区(ITS)序列包括5.8SrDNA及其叶片的解剖。结果表明(1)5种大戟属植物的ITS的长度范围为641~662bp,运用Maga软件构件ITS树把5种植物归为两大支大戟、月腺大戟与乳浆大戟聚为一支;地锦和斑地锦聚为另一支。结果表明地锦和斑地锦亲缘关系较近,而大戟、月腺大戟和乳浆大戟亲缘关系较近。(2)5种大戟属植物的叶片结构中,除地锦和斑地锦外,其余3种有明显的栅栏组织和海绵组织之分,但二者在叶肉中的厚度比在种间有一定的差别;而地锦和斑地锦叶的栅栏组织与海绵组织分化不明显,且皆有乳汁管,其他3种植物叶片内未见此结构,叶片结构分析表明大戟、月腺大戟和乳浆大戟叶片结构相近,而地锦草和斑地锦叶片结构也相近。(3)分析表明nrDNA的ITS序列及叶的比较解剖特征具有明显的相关性。以上研究结果为大戟属植物的分类和药用开发提供了实验证据。     

Observations on the ascending aortic fold in two chacma baboons (Papio hamadryas ursinus)

Baboons (Papio) were used to study the ascending aortic fold. The fold was present in two out of 20 hearts examined. Its position and shape was comparable to that observed in human subjects. The principal difference was the absence of paraganglia. The functional role of the baboon fold is unclear.     

The braincase of Typhlops and Leptotyphlops (Reptilia: Serpentes)

The structure of the braincases and associated nerves and blood-vessels is described. Typhlops combines primitive lacertilian features, notably the retention of a palatine artery, with specialisations such as the structure of the recessus scalae tympani. Leptotyphlops is more completely snake-like, but the two genera show in common a specialised intracranial course of the hyomandibular branch of the facial nerve, due to lateral closure of the juxtastapedial recess by the overgrowing crista circumfenestralis. The lateral closure of the juxtastapedial recess is considered as an adaptation to burrowing habits. The Vidian canal in scolecophidians is poorly defined, due to the lack of lateral ascending wings of the parasphenoid. This might constitute an archaic character contradicting the descent of snakes from any Recent lacertilian group.     

贵州省常见唇形科植物茎和叶比较解剖学研究

运用石蜡切片技术对贵州省40种常见唇形科植物茎、叶进行了比较解剖学研究。结果显示:(1)40种唇形科植物具有典型的双子叶植物茎、叶的解剖特征,茎由表皮、皮层和维管柱组成,棱角表皮下具有发达的厚角组织,棱角处厚角组织内方的维管组织明显较其它部分发达;茎横切面形态主要有3种类型,维管束排列也主要呈现3种方式。(2)叶片由表皮、叶肉和叶脉三部分组成,均为异面叶,栅栏组织细胞1~3层,少部分物种叶脉腹面隆起;绝大部分常见物种主脉明显较侧脉发达,但也有少部分主脉、侧脉大小相近;主脉中维管束大多为1个,形态包括月牙形、半圆形、圆形,少量物种主脉具有多维管束;表皮毛由1~3个细胞组成,表皮毛的形态多为锥状,少为杆状。研究表明,唇形科植物茎、叶的显微结构无论在属内还是在种间都存在差异,在探讨唇形科种的分类地位及其物种鉴定时都具备参考价值,但却难以作为分类鉴定的决定性特征。     

东亚和北美当归属（广义）的果实解剖和演化

应用比较解剖研究了广义当归属在世界主要分布区－东亚和北美种类的果实结构的特征。根据分生果背腹压扁的程度、棱翅与槽的形状、果皮层次和结构、油管数目、大小和位置等稳定性状,可将果实分为５个类型,与《中国植物志》将其分为５个属,即古当归属,当归属,高山芹属,柳叶芹属和山芹属的意见相一致。古当归属为原始的类型,山芹属具有高度演化的特征。且对一些种类有分类位置提出了调整的意见和各属的演化趋势。