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1.
The morphology of the slender, filiform spermatozoa of 13Protodrilus species of 22 different populations is investigated by light and transmission electron microscopy. All species have two types of spermatoza: fertile euspermatozoa, and paraspermatozoa, which are probably infertile and may comprise up to 20% of the total number of mature gametes. This is the first record of sperm dimorphism in polychaetes. The general construction pattern of the euspermatozoa is very complex. It shows a longish tapering acrosomal vesicle with an internal acrosomal rod, a rod-like conical nucleus, and a midpiece with numerous very complex supporting elements and two thin mitochondrial derivatives. Further, it has a ‘peribasal body’ surrounding the basal body of the axoneme, an anulus region with an ‘anchoring apparatus’ and an anulus cuff. Posteriorly, the tail region proper contains in some species 2 to 9 supporting rods. In several species the euspermatozoon shows very distinct and species-specific alternations of this ‘general pattern’ relating to e.g. size of sperm elements, structure of acrosome and nucleus, presence or absence of axial rod, and number, shape and size of supporting elements in midpiece and tail. In a number of species some sections of the euspermatozoon overlap with each other more or less strongly. The paraspermatozoon has a comparatively simple construction pattern and possesses no supporting structures in midpiece and tail region. The midpiece is very short and, in some species, entirely surrounded by its two thin and elongate mitochondrial derivatives. An axial rod is often missing or reduced; different sperm sections never overlap each other. In contrast to the euspermatozoa, the paraspermatozoa of the different species have a very similar ultrastructure. Their possible function in spermatophore transfer and histolytical opening of the female epidermis is discussed. A comparison of the different forms of euspermatozoa inProtodrilus elucidates possible plesiomorphous and apomorphous sperm traits. Very likely, the hypothetical plesiomorphous type of spermatozoa inProtodrilus has a very similar morphology to that of the paraspermatozoa, which for this reason are considered to be a sort of persisting representatives of the ancientProtodrilus sperm type. InProtodrilus, the different traits of the euspermatozoa represent excellent taxonomic characters for distinguishing species (e.g. ‘sibling species’). They can also be used well for phylogenetics within the genus, whereas the relations ofProtodrilus to other polychaete groups cannot be clarified solely on the basis of sperm characters, since in all groups the sperm structure is primarily an adaptation to a specific mode of reproduction. Generally, the value of sperm characters in phylogenetic considerations at higher taxonomic levels seems to be very limited due to the surprisingly wide range of different sperm structures within a single genus as is demonstrated in the present paper.   相似文献   

2.
Die Kombination (Koppelung) der Stoffe im Chemosyndrom kann gegenseitig oder einseitig obligat oder auch fakultativ sein. Dabei ist die Stellung der beteiligten eng verwandten Produkte im Rahmen der Biosynthese von Fall zu Fall verschieden. — Dem Chemotaxonomen kann die Berücksichrigung dieser Aspekte zumindest tendenziell als Anhaltspunkt dienen. Bei Vorkommen der Komponenten in verschiedenen Verwandtschaftskreisen wird man ein Chemosyndrom - also eine Kornbination biogenetisch eng verwandter Verbindungen - urn so eher als ein einziges Merkmal betrachten können, je seltener die Kombination aufgelöst ist. Zweifellos stellen der solitare Stoff als Einzelmerkmal und die ohne Ausnahme auftretende (obligate) Kombination als Einzelmerkmal nur Extreme einer gleitenden Reihe dar. Herrn Prof. Dr. E. KLUG (Berlin) danke ich für die Durchsicht des Manuskripts und für werrvolle Diskussion, Herrn H. LÜNSER für die sorgfältige Ausführung der Zeichnungen, Frau I. EGGERT, Frau C. MÜLLER und Frau 1. POHL für die Hilfen bei der Vorbereitung des Manuskripts. Herrn Dr. M. SEAWARD (Bradford) bin ich für Beratung und Diskussion in Zusammenhang mit der Form der englischen Zusammenfassung sehr zu Dank verpflichter,  相似文献   

3.
A new species of Deinsdorfia is defined using new material coming from the karstic fissure infilling of Almenara-Casablanca 4 (Castelló, Spain), which shows important differences with the rest of the previously known species of the genus. The definition of a new species is supported by the characters found in extra material coming from the localities of Valdeganga, in the Albacete Province (Spain). The stratigraphical occurrence of this genus of pigmented-toothed shrews reinforces the idea of the Iberian Peninsula as a sink area during the Pliocene, where some Central-European soricids expanded their distribution. Most of those migrations or distributional expansions coincide with moments of climatic changes in the northern hemisphere.  相似文献   

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5.
Yin-Ping  Fang  Ling-Ling  Lee  Fu-Hsie  Yew  Hon-Tsen  Yu 《Journal of Zoology》1997,242(1):151-166
We define the species boundaries of white-toothed shrews (genus Crocidura ) in Taiwan using karyological and morphological characteristics. Ninety-nine animals were obtained from all over Taiwan at capture rates usually less than 10%. Three species are recognized by distinct cytotypes: Crocidura attenuata tanakae 2n = 40, FN = 56; Crocidura suaveolens hosletti 2n = 40, FN = 50; Crocidura kurodai 2n = 40, FN = 54. A suite of six morphological characters diagnose the three species: shape of skull, position of incisive foramina, shape of fourth upper premolar, shape of pinna, tail vibrissae, and foot pads. A species key and notes on the life history of each species are provided. Finally, we discuss chromosomal evolution and biolgeography of Crocidura in East and South East Asia.  相似文献   

6.
Phylogenetic relationships among the three described species of short-tailed shrews (genus Blarina) were inferred based on mitochondrial DNA sequences of 16S rRNA (506 bp) and cytochrome b (1137 bp) from 38 specimens representing B. brevicauda, B. hylophaga, and B. carolinensis, from across their range in North America. Phylogenetic analyses of both data sets combined followed tests showing lack of incongruence between these fragments. Analysis of substitution patterns indicated saturation of transitions at third codon positions in cytochrome b when Blarina sequences were compared to those of Sorex and Cryptotis, used as outgroups. Maximum-likelihood and weighted parsimony supported the monophyly of the genus and placed B. hylophaga as its basal branch, sister to B. brevicauda + B. carolinensis. Phylogeographic analysis revealed a significant partition between eastern and western populations of B. carolinensis and B. brevicauda, on either side of the Mississippi basin. These results are discussed in relation to cytogenetic, morphological, and fossil data.  相似文献   

7.
Niche occupation by 5 goby species (Teleostei, Gobiidae) in the Baltic Sea and its interpretation by means of the theory of pre-adaptation The habitats and prey of five goby species were investigated near the shore of the Lübeck Bight (SW Baltic) during the period 1989–1991. Observations showed that Gobius niger is a macrobenthos feeder, Pomatoschistus microps a meiobenthos feeder; Pomatoschistus pictus prefers meiobenthos as well as plankton while Pomatoschistus minutus feeds on benthos of every size, as well as planktonic cope-pods when offered in surplus; Gobiusculus flavescens is generally a plankton feeder but, when this component is in short supply in the summer, changes to macrobenthos. P. pictus and P. microps existed at different depths; G. flavescens and P. minutus presented countercurrent densities in shallow habitats during the course of a year. This adaptability of behaviour in habitat and prey choice can be explained by the modification ability of pre-adaptional genes in the goby genomes. After having invaded species-poor habitats such as the brackish Baltic Sea, wide niche dimensions are initially occupied. The niche is here considered to be an attribute of the species as well as of the habitat according to GÜNTHER (1950). Hence, innidation is defined as a process which implies specialization by loss of most preadaptations and leads to the optimal use of the ecosystem by the species. This process of a single species corresponds to the maturation of successions of whole biocoenoses.  相似文献   

8.
孙悦欣 《动物学杂志》2010,45(4):171-172
在整理采自辽宁省新宾县鼩鼱属(Sorex)标本时,发现小鼩鼱(S.inutus Linnaeus,1766)为辽宁省新纪录。主要特征为上颌第二单尖齿小于第一、三单尖齿,第五单尖齿小,约为第四单尖齿的2/3高。下颌门齿向前延伸甚长,其上切缘有3个深缺刻,犬齿小,是下前臼齿2/3高。  相似文献   

9.
10.
Fossil mandibles of the Bornean shrew Crocidura foetida recovered from excavations at the west mouth of Niah cave, Sarawak, Malaysia, show that the late Pleistocene population at this lowland location was comparable in size with the large subspecies Crocidura foetida doriae , presently occurring at inland, upland locations. Two Holocene specimens fall in the size range of the smaller lowland subspecies C. f. foetida . Comparable post-Pleistocene size-reduction is known among other mammals of Borneo, but this is the first instance of dated examples. The evolutionary trend conforms with Bergmann's 'rule' but, other than climate change, no selective agent is apparent.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 413–419.  相似文献   

11.
Soricid remains collected from Bed I of Olduvai Gorge are described. The great majority of the specimens are mandibles. A survey of the mandibles of living African species revealed many differences in characters of the lower teeth and jaw that can be used for identification. On the basis of these characters, nine species are distinguished in the Olduvai collection, of which six are well enough preserved to permit a discussion of their relationships to living species. Three new species and one new subspecies are described. All the Olduvai shrews differ in some respects from their nearest living relatives; three species are close to species from Makapansgat, Swartkrans and Sterkfontein, RSA, though there appear to be slight differences. A change in the soricid fauna takes place within Bed I, interpreted as due to increasing aridity.  相似文献   

12.
13.
Five European Water Shrews (Neomys fodiens) were kept in an indoor enclosure of 2.7 m2 where one couple mated regularly. Multiple copulations appeared over a period of about 12 hours. Ten litters with 56 offspring were born and 33 survived. The female gave birth to her latest litter at an age of about 20 month, 2 month later as the end of the reported lifespan in nature. The period of fertility lasted 336 days and is comparable to those of Crocidura. At the end of this period three times signs of pseudopregnancy were detected: After copulating the female started building her nest and intensified this behaviour after about three weeks, at the end of the expected “gestation” swollen nipples could also be noticed, but no offspring inside the nest. The female died at an age of about 38 month.After successful copulations a copulatory lock was achieved and the female could track her mate. The mating behaviour can be classified as follows: a) male entering female's territory, b) precopulatory chasing, c) approaching of the mates, d) mounting and repeated copulations attempts, e) successful copulation, male slipping down from female's back, f) copulatory lock and resting, g) cleaning sexual organs, h) continuing chasing and further copulations or i) displacing the male and finishing sexual behaviour. Driving off the male from female's territory could last some time. No special calls were uttered in the close context of copulatory behaviour, only the known ones while chasing, some low contact calls inside the nest and aggressive calls while driving off the male.  相似文献   

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15.
The carapace grooves of decapod Crustacea are hitherto considered as remnants of somit boundaries. This hypothesis is rejected for theoretical reasons and on the basis of morphological studies of recent crayfishes and lobsters. The grooves are recognized as mechanically induced secondary structures resulting from the attachment of different muscles to the carapace. The grooves can be used for the diagnosis of certain systematic groups, but are of little value for phylogenetic considerations.  相似文献   

16.
2018年11月,在西藏自治区林芝地区波密县扎木镇(29°48′25″ N,95°41′56″ E)海拔3 400 m处捕获1只缺齿鼩属动物。该个体背毛深灰色,腹面毛色稍淡,呈苍灰色;尾长明显大于头体长,背腹异色不明显,尾部末端缺少簇毛;头骨坚固,头盖骨隆起明显,颧骨板很窄,齿式3.1.1.3/2.0.1.3 = 28,这些特征与烟黑缺齿鼩(Chodsigoa furva)的鉴别特征一致。通过测定其Cyt b基因全序列,并结合从GenBank下载的缺齿鼩属已有同源序列构建的最大似然树显示,该个体与烟黑缺齿鼩聚为一支(支持率BS为100),与云南地区烟黑缺齿鼩的遗传距离在2.25% ~ 2.34%之间。基于以上形态和分子结果确认该个体为烟黑缺齿鼩,是该物种在西藏的首次分布记录。  相似文献   

17.
于2013年和2018年在河南信阳新县与浉河共采集到3号鼩鼱成年个体标本,基于齿色特征初步鉴定为劳亚食虫目鼩鼱科麝鼩属(Crocidura)物种。对所采3号标本的Cyt b基因进行PCR扩增和测序,测序结果与GenBank数据库进行比对,并通过构建系统发育关系树进一步明确所采3只标本的分类地位。根据标本形态、头骨特征,结合分子生物学证据,确定该物种为台湾灰麝鼩(C.tanakae),为河南哺乳动物分布新记录种。标本现存于郑州大学生物多样性与生态学研究所(编号分别为IBE20131005、IBE2018100501和IBE2018100502)。  相似文献   

18.
Halbach  Udo 《Oecologia》1972,9(4):311-316
Summary Coefficients of interspecific association of three rotifer species (Brachionus calyciflorus, Brachionus rubens, Asplanchna brightuelli) of 314 plankton samples from about 100 ponds in South Germany were determined: two coefficients basing on present-absent data (Table 2: C 7, C 8), one coefficient regarding population density (Table 2: C 9), and one coefficient of partial interspecific association taking in mind the presence or absence of the third species (Table 3: C p). Some of the computed coefficients are significantly positive or negative indicating that joint appearances are sometimes more and sometimes less frequent than expected by chance. Most of these results cam be interpreted by the knowledge of interspecific relationships, vz. competition between Brachionus calyciflorus and B. rubens, and predator-prey relationships between Asplanchna brightwelli and B. rubens which had been detected in former studies. In each case the association between two of the species is modified by the presence of the third. The causes (alternative prey, destruction of the competitors etc.) are discussed.  相似文献   

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In order to develop a new accurate method for sexing in Sorex species (Soricidae, Insectivora), we synthesized a polymerase chain reaction (PCR) primer set to amplify a part of Sry HMG box in the long‐clawed shrew, Sorex unguiculatus. When the primers were applied to the samples of known sex, PCR products were successfully obtained for males as a clear, single band on 3% agarose gels after electrophoresis in Sorex unguiculatus and five other Sorex species, but not for females of these six species. Thus, PCR amplification using the primer set may be applicable to discern sex in the six Sorex species.  相似文献   

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