Biochemical genetic variation in the genus Littorina (Prosobranchia:Mollusca)

The genus Littorina has been subject to many studies of electrophoretically detectable variation, mostly aimed either at clarifying questions concerned with population structure, or at clarifying difficult taxonomic/systematic problems. This paper reviews many of these studies. Topics covered include Hardy-Weinberg deviations, the extent of genetic differentiation among populations within species, founder effects and the effects of human introductions on genetic variation, the biological significance of allozyme variation, and the uses of allozyme variation in Littorina systematics.     

四种露螽消化道内壁的电镜观察

主要运用生理解剖及扫描电镜技术对螽斯总科露螽科Phaneropteridae 4种螽斯消化道的内部结构进行了比较.     

Comparative morphology and cytology of the alimentary tract in lizardfishes (Teleostei,Aulopiformes, Synodontidae)

Fishelson, L., Golani, D., Russell, B., Galil, B. and Goren, M. 2012. Comparative morphology and cytology of the alimentary tract in lizardfishes (Teleostei, Aulopiformes, Synodontidae). —Acta Zoologica (Stockholm) 93 : 308–318. This study compares the morphology and cytology of the alimentary tract in several species of lizardfishes (Synodontidae, Teleostei) of the genera Saurida, Synodus, and Trachinocephalus, in relation to their diets and bathymetric distribution. All the studied species feature a large, pouch‐like stomach, with the intestine beginning at the stomach’s anterior apex, adjacent to the esophageal opening. In the more ‘microphagous’Synodus spp. and Trachinocephalus, the intestine bends twice before reaching the anus, whereas in the more ‘macrophagous’Saurida spp., the intestine extends straight to the anus. The species differ also in the number and form of their pyloric ceca, the length of the intestine and in the percentile relationship between stomach length and standard body length. Along the alimentary tract folds and villi protrude into the lumen, their numbers differing on various sites of the tract. Three cell types make up the gastric gland system: (1) pyramidal cells forming the tubular gastric glands in the lamina propria; among them are large, pale secretary cells; (2) groups of neck cells that surround the pits of the tubules; and (3) groups of large and granule‐rich cells at the end portion of the stomach. All species are carnivorous and uniform in morphology, the differences in the alimentary tract found between the more shallow‐water species of Synodus and Trachinocephalus, and the deeper‐dwelling Saurida, seem to be only partly correlated with the differences in diet.     

Quantitative morphological variation inTetramolopium (Asteraceae) in Hawaii and the Cook Islands

Multivariate analyses of quantitative characters were undertaken to examine the pattern of variation resulting from adaptive radiation ofTetramolopium in Hawaii and to investigate the systematics of an undescribed species in the Cook Islands and a group of populations of uncertain affinity on Kalaupapa Peninsula in Hawaii. Taxa differentiated on quantitative characters in the absence of qualitative characters. Differentiation was observed in multiple characters which could be organized into a few principal components. The analyses supported the species rank of the Cook Islands plants. The relationship of the Kalaupapa Peninsula populations to the rest of the taxa needs further study.     

Morphological and ultrastructural characterization of the alimentary canal in larvae of Streltzoviella insularis (Staudinger) (Lepidoptera: Cossidae)

Streltzoviella insularis (Staudinger) is an important tree‐boring pest, that primarily damages Sophora japonica (Linnaeus) and Ginkgo biloba (Linnaeus), as well as other common species, at great economic cost to the urban landscape construction industry in China. In the present study, the alimentary canal morphology of S. insularis was observed using light microscopy, and its ultrastructure was investigated by scanning and transmission electron microscopy. The foregut of S. insularis can be divided into the pharynx, esophagus, crop, proventriculus, and cardiac valve. The well‐developed crop forms the longest section of the foregut. It is able to store large amounts of food and is lined with a monolayer of epithelial cells. Many sclerotized microspines occur on the surface of the anterior intima and there are dense spines on the posterior intima of the proventriculus. Epithelial cells of the midgut include columnar cells, goblet cells, and regenerative cells, but endocrine cells are absent. The hindgut consists of the pyloric valve, ileum, and rectum. There is no clear distinction between the ileum and colon. The intima surface of the pyloric valve carries many microspines, whereas the intestinal wall of the rectum is thin with well‐developed rectal pads. The rectal epithelial cells form a squamous monolayer. A cryptonephric excretory system is located in the hindgut. There are six spiral Malpighian tubules, in which a cellular layer on a basement membrane encloses a lumen. These results will provide the basis for further studies of the structure and function in S. insularis larvae.     

Reproductive skew, costs, and benefits of cooperative breeding in female wood mice (Apodemus sylvaticus)

Two current models seek to explain reproduction of subordinatesin social groups: incentives given by dominants for peacefullyremaining in the group (reproductive skew model) or incompletecontrol by dominants. These models make different predictionsconcerning genetic relatedness between individuals for thedistribution of reproduction and the stability of cooperativebreeding associations. To test these models and to furtherexplore the relationships between reproductive skew, geneticrelatedness, and investment of each participant, we performedbehavioral observations of female wood mice (Apodemus sylvaticus)raising pups communally. Our results do not support previousmodels. Differences in lifetime reproductive success were significantlygreater within mother—daughter pairs than within pairsof sisters or unrelated females. Subordinate females of eitherbreeding unit did not differ in their direct reproduction.Calculations of inclusive fitness based on our results leadto the following predictions: (1) Communal nests should occuronly when ecological circumstances prevent solitary breeding.(2) Subordinate females gain the highest inclusive fitnessjoining their mothers; they also show the highest nursing investment.(3) Mothers should accept daughters, who have no opportunityfor solitary breeding. (4) Dominant sisters and unrelated femalesshould reject subordinate females because cooperative breedingreduces their reproductive success. However, breeding unitsof dominant sisters and unrelated females nevertheless occurand can be explained by our finding that such females significantlyreduce nursing time, which may help them save energy for futurebreeding cycles. Our data demonstrate that both genetic relatednessand investment skew are important in the complex evolutionof reproductive skew in cooperative breeding.     

中华稻蝗全消化道内壁显微结构观察

本文采用扫描仪和扫描电镜对中华稻蝗消化道内壁的细微结构进行了系统观察和研究。结果表明,中华稻蝗食道内壁由纵行脊组成,前端有齿。嗉囊包括两段,前段的一个小的膨大部分,由V-形区和两侧的V-形脊组成,只在前端内壁有齿;后段为一个大的膨大部分,由柳叶脊、扇形脊和不规则脊组成,脊的上缘有齿。前肠内壁的齿主要为单生齿,除贲门瓣上齿的齿尖指向前方外,全部齿的齿尖指向后方。后肠的前端为12个幽门瓣,内壁有齿。回肠和结肠由6条纵行脊组成,结肠内壁有齿。直肠的齿在除直肠垫外的直肠内壁上。后肠的齿主要为丛生齿,后肠除直肠内壁齿的齿尖指向附着环外,全部齿的齿尖指向后方。根据我们的观察,对前肠提出了新的分区。     

六种螽斯消化道形态及其分类学价值的研究(直翅目:螽斯总科:草螽科)

主要运用生理解剖及扫描电镜技术对螽斯总科草螽科Conoccphalidac 3属6种螽斯的消化道内部结构进行了比较分析。研究表明,螽斯消化道尤其是前肠的内部形态,属间差异明显,可以作为螽斯内部解剖形态分类的一个有用的特征,并为研究螽斯各类群间的亲缘关系和螽斯的演化提供新的依据。     

Shell variation in sympatric freshwater Lymnaea peregra and L. ovata (Gastropoda: Lymnaeidae)

Snails of the genus Lymnaea are morphologically variable and their taxonomy is unclear. In particular, the forms peregra and ovata , distinguished by shell shape, are often considered variants of the same species, L. peregra. We studied a rare situation in a Swiss mountain lake where both forms are sympatric. First, we found that the forms shows complete separation for a number of allozymes. Second, we examined the response of the two snail forms to infection by the trematode Diplostomum phoxini . For the ovata form, there was a transitory, 10% increase in the growth of infected snails compared to uninfected controls. The peregra form showed no gigantism and had higher parasite-induced mortality. Third, we assessed differences between the forms in reproduction under different environmental conditions. Density negatively influenced egg production to the same degree in both forms. However, decreasing water levels, characteristic of part of the lake studied, led to a 30% decrease in egg production for the ovata form, but only a 10% decrease for the peregra form. These differences are discussed in relation to the microdistributions of the snails in the lake and we conclude that the two forms are almost certainly separate species.     

Early evolutionary differentiation of morphological variation in the mandible of South American caviomorph rodents (Rodentia, Caviomorpha)

Caviomorphs are a clade of South American rodents recorded at least since the early Oligocene (> 31.5 Ma) that exhibit ample eco-morphological variation. It has been proposed that phylogenetic structure is more important than ecological factors for understanding mandibular shape variation in this clade. This was interpreted as a result of the long-standing evolutionary history of caviomorphs and the early divergence of major lineages. In this work, we test this hypothesis through the analysis of morphological variation in the mandible of living and extinct species and compare this information with that obtained through comparative phylogenetic analyses. Our results support the hypothesis of early origin of mandibular variation; moreover, they suggest the conservation of early differentiated morphologies, which could indicate the existence of constrained evolutionary diversification.     

Evidence for a phylogenetic position of button quails (Turnicidae: Aves) among the Gruiformes

The phylogenetic position of the Turnicidae (Aves) was unresolved. Historically, they were classified as members of the Struthioniformes, Galliformes, Charadriiformes, Columbiformes or the Gruiformes. In these classifications they had taxonomic rank of order 'Turniciformes' or family 'Turnicidae'. However, most of these studies followed phenetic methodology and used morphological similarity of taxa and plesiomorphic characters to classify Turnix . Recent phylogenetic studies on the basis of morphological character analyses or phenetic comparisons based on DNA-DNA hybridization experiments failed to clarify the phylogenetic realtionship of Turnix and suggested a position as 'incerte sedis', either among the Gruiformes or as the parvclass 'Turnicac'as a sistergroup to the 'Neoaves'.
We studied skeletal and myological material of Turnix to resolve its phylogenetic position. Further, we considered all characters that were previously discussed in literature to classify Turnix and tested them for their potential use in phylogenetic analysis. We added several yet unemployed morphological characters of phylogenetic significance to the analysis. The Struthioniformes, 'Galloanseres', and Columbiformes are each characterized by a clear set of autapomorpies. Only one autapomorphy in known for the Gruiformes but this character is of satisfying consistency and can be found in all families of the Gruiformes (Gruidae, Psophiidae, Aramidae. Rallidae) and Turnix. Turnix and the Rallidae share four complex morphological characters implying a close phylogenetic relationship. The data presented in this paper support the hypothesis that Turnix is a member of the Gruiformes with close relationships to the Rallidae. No evidence was found that would support a parvclass 'Turnicae'as sistergroup to the 'Neoaves'.     

Morphometric and morphological delineation of southern African species of Aethomys (Rodentia: Muridae)

Five species of African rock rats, Aethomys namaquensis, A. granti, A. silindensis, A. nyikae and A. chrysophilus, have to date been recognized in southern Africa. While the first three species are craniometrically well-delineated, morphometric analysis of cytogenetically known and other specimens of A. chrysophilus revealed that it comprises two sympatric, morphologically similar species, the nominate species and the newly recognized A. ineptus. This is in agreement with observations on cranial morphology and earlier investigations involving cytogenetics, protein electrophoresis, and gross sperm and bacular morphology. Contrary to published reports, the Central African A. nyikae does not extend into southern Africa, and the single previous record from eastern Zimbabwe is probably based on a misidentification.     

Functional morphology of the stone canal in the sea urchin Eucidaris (Echinodermata: Echinoidea)

The lack of mesocoelomic pores and the existence of a stone canal connecting proto-and mesocoel are characteristic peculiarities of echinoderms in contrast with the situation in other trimeric archicoelomates. The ultrastructure of the stone canal has been studied in order to understand its function in the strategically important position between two coelomic spaces with different functions. The epithelium of the Eucidaris (Echinoidea) stone canal is composed of three cell types: (1) ciliated cells, (2) cells with long basal processes containing myofilaments, and (3) granulated cells, which may represent secretory neurons. Nerve fibres of two types are common in the epithelium. We consider the stone canal to be a structure controlling fluid transport; its wall may exert peristaltic movements or tonic contractions and dilations which are under control of the nervous system. The ciliated cells additionally may have phagocytotic capacities. Similarities with the fine structure of the wall of the mesocoelomic pores in the pterobranch Cephalodiscus are discussed.     

Suprageneric relationships of galliform birds (Aves, Galliformes): a cladistic analysis of morphological characters

Of the basal clades of extant birds (Neornithes) the 'landfowl' or galliforms (Aves, Galliformes) are the most speciose. Cladistic analysis of more than 100 morphological characters coded at the generic level for most putative galliform genera confirms that the megapodes ('mound builders'; Megapodiidae) are the most basal clade within the order. They are followed successively by the curassows, guans and chachalacas (Cracidae), which comprise the sister-group to all other extant Galliformes (i.e. Phasianoidea). Within this large 'phasianoid' clade, analyses suggest that the guineafowl (Numididae) are the most basal taxon, although monophyly of this 'family' is not strictly supported on the basis of the morphological characters employed. An additional major clade within the phasianoid Galliformes is recovered by this analysis, comprising the traditional groupings of New World quails (Odontophoridae) and Old World quails ('Perdicini'), yet only monophyly of the former is supported unambiguously by morphological characters. Relationships within the remainder of the phasianoid taxa, including the grouse (Tetraonidae), turkeys (i.e. Meleagris / Agriocharus spp.) as well as other 'pavonine' galliforms (i.e. peafowl; Pavo , Afropavo , Rheinardia , Argusianus and Polyplectron spp.) remain largely unresolved on the basis of morphological characters, yet monophyly of the major subdivisions is supported here. Although there are a number of important differences, especially with regard to relationships within the nonquail phasianoids, the results of this morphological phylogenetic (cladistic) analysis are broadly congruent both with traditional classifications and existing molecular hypotheses of galliform phylogenetic relationships.     

Phylogeny of Acomys spinosissimus (Rodentia, Muridae) from north Malawi and Tanzania: evidence from morphological and molecular analysis

New specimens of Acomys spinosissimus from northern Malawi and southern Tanzania were subjected to morphological, molecular (cytochrome b mitochondrial gene) and cytogenetical analysis in order to establish the phylogenetic position of these populations among A. spinosissimus, as well as their relationships with other species (A. subspinosus and A. wilsoni). The monophyly of the spinosissimus clade is supported by morphological and molecular phylogenies. Cytogenetics and morphology, but not the cytochrome b phylogeny show the possible existence of two sibling species within spinosissimus. Incongruences are noted between molecular and morphological trees, especially concerning the position of the Transvaal specimens. Two different biogeographic scenarios for the origin and dispersal of A. spinosissimus are discussed in the light of available palaeontological data.