首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Temnocephala brevicornis Monticelli 1889, ectosymbiont of Hydromedusa tectifera Cope 1869, is reported for the first time for Argentina. Numerous temnocephalans from Arroyo Villoldo in the locality of Magdalena, Buenos Aires, Argentina were stained in toto to be studied. This commensal species in turtles was originally cited in association with Hydromedusa maximiliani (Mikan) and Hydraspis radiolata Mikan in Brazil. Afterwards, it was found on other fresh water turtle species in Brazil and Uruguay.  相似文献   

2.
This report describes the first occurrence of Polystomoides brasiliensis n. sp. (Monogenea: Polystomatidae), a new monogenean species in the buccal and pharyngeal cavities of the freshwater turtles in Brazil. Live monogeneans were collected from Hydromedusa maximiliani and Phrynops geoffroanus at the Mariano Procópio Museum's lake, in Juiz de Fora, Minas Gerais, Brazil. Polystomoides brasiliensis differs from all other species of this genus in having 8-9 genital spines, except for Polystomoides uruguayensis, which has 8-10 genital spines. However, the new species differs morphometrically from P. uruguayensis in the greater size of the outer and inner hamuli, as well as having a testis that is proportionally greater than the pharynx and oral sucker. The current study is the first report of monogeneans in chelonians of Brazil, and the first record of helminths in H. maximiliani.  相似文献   

3.
Max Fischer 《BioControl》1969,14(2):129-147
A key for identification of 23 species of the Opiine-genusEuopius Fischer from America and Sumatra is given. Eigth species are described as new:Euopius basiarmatus, E. completus, E. encoensis, E. maximiliani, E. normalus, E. paganus, E. pygmosoma andE. rugificus. The species already known are listed with their original citations only.  相似文献   

4.
This article documents the addition of 228 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Anser cygnoides, Apodemus flavicollis, Athene noctua, Cercis canadensis, Glis glis, Gubernatrix cristata, Haliotis tuberculata, Helianthus maximiliani, Laricobius nigrinus, Laricobius rubidus, Neoheligmonella granjoni, Nephrops norvegicus, Oenanthe javanica, Paramuricea clavata, Pyrrhura orcesi and Samanea saman. These loci were cross-tested on the following species: Apodemus sylvaticus, Laricobius laticollis and Laricobius osakensis (a proposed new species currently being described).  相似文献   

5.
Morphological and molecular data yield incongruent hypotheses concerning the interrelationships of chelid side-necked turtles, neither of which is widely accepted. Molecular studies recognize monophyletic South American and Australasian clades, whereas morphological characters distinguish a long-necked clade and a short-necked clade. We take a developmental approach to exploring chelid interrelationships. None of the nine species studied have the same growth pattern for all measurements examined, indicating changes in ontogenetic scaling of cranial characters was common during chelid evolution. The variability in scaling relationships precludes overwhelming support for either hypothesis. Scaling patterns are most similar between the geographically separate clades promoted by molecular analyses, and hence our data favor an independent origin of the long neck in South American and Australasian species. A close relationship between Hydromedusa and Chelus, rather than Chelodina, is supported by scaling patterns associated with a relative widening of the cranium. Our study exemplifies the utility of comparative ontogenetic trajectory data to test phylogenetic hypotheses.  相似文献   

6.
Meiotic cells of transgenic asymmetric somatic hybrid (ASH) plants obtained by fusion of microprotoplasts of the donor species Helianthus giganteus or Helianthus maximiliani and recipient protoplasts of Helianthus annuus were investigated. Over 85% of the ASH meiocytes showed regular bivalent chromosome pairing; however, several anomalies like anaphase bridges, laggard chromosomes, univalent and multivalent pairing were also observed. Pollen viability of the ASH plants ranged from 79.2 to 95% with a strong negative correlation to chromosome number which varied between 34 and 42. Molecular investigation of ASH progeny using RAPD markers revealed the presence of donor genotype markers in 68% of the offspring. These results suggest that asymmetric somatic hybridization offers an efficient alternative method to overcome sexual barriers for gene flow and the genetic improvement of H. annuus by introgression of economical important traits from wild Helianthus species. Received: 16 July 2000 / Accepted: 25 September 2000  相似文献   

7.
Amniote egg and eggshell morphology is a rich source of characters to link aspects of reproductive biology with systematics. Extensive work concerning both anatomy and phylogenetic assignability has been done on fossil bird and dinosaur eggs, but little is known for extant sauropsids. The utility of eggshell characters for phylogenetic analyses is tested and discussed for extant side-necked turtles (Pleurodira), and the diversity of egg ultrastructure is examined in several species. Egg gross morphology and eggshell ultrastructure of 12 species of extant side-necked turtles was documented using scanning electron microscopy. Thirteen eggshell characters were scored and mapped on a composite phylogeny and ancestral character states were reconstructed. Many of the characters do not show a phylogenetic signal according to a test comparing the number of steps on the chosen phylogeny with that on randomly generated trees. The presence of conservative, clade-supporting features could be demonstrated, and the following clades are supported by several characters: the Elseya-Emydura entity, short-necked Australasian chelids, is backed by two characters, and two additional characters could potentially support this group. Three characters support the monophyly of South American chelids, whereas two characters argue for the exclusion of Hydromedusa, a long-necked form resembling Australian chelids rather than South American forms, from this clade.  相似文献   

8.
In plants, ecologically important life history traits often display clinal patterns of population divergence. Such patterns can provide strong evidence for spatially varying selection across environmental gradients but also may result from nonselective processes, such as genetic drift, population bottlenecks and spatially restricted gene flow. Comparison of population differentiation in quantitative traits (measured as Q(ST) ) with neutral molecular markers (measured as F(ST) ) provides a useful tool for understanding the relative importance of adaptive and nonadaptive processes in the formation and maintenance of clinal variation. Here, we demonstrate the existence of geographic variation in key life history traits in the diploid perennial sunflower species Helianthus maximiliani across a broad latitudinal transect in North America. Strong population differentiation was found for days to flowering, growth rate and multiple size-related traits. Differentiation in these traits greatly exceeds neutral predictions, as determined both by partial Mantel tests and by comparisons of global Q(ST) values with theoretical F(ST) distributions. These findings indicate that clinal variation in these life history traits likely results from local adaptation driven by spatially heterogeneous environments.  相似文献   

9.
Temnocephala brevicornis Monticelli, 1889 is the only species of the genus Temnocephala Blanchard, 1849 reported from chelonians to date. During a survey of the species of Temnocephala extant in southern Uruguay, two new species were found on the chelonian Hydromedusa tectifera Cope, 1869. They are described here as Temnocephala pereirai n. sp. and Temnocephala cuocoloi n. sp. Both resemble T. brevicornis, but differ in the morphometry of the penial stylet, and in qualitative details of the reproductive complex. Temnocephala pereirai n. sp. differs from T. brevicornis by having a massive, cylindrical sphincter in the distal portion of the vagina, and a seminal vesicle that opens into the subpolar to equatorial portion of the contractile vesicle. In addition, the penial stylet in Temnocephala pereirai n. sp. is large in relation to body size, straight and more slender, having the distal portion of its shaft slightly sinuous, and a smaller introvert equipped with about 16 distal crowns of smaller spines. Temnocephala cuocoloi n. sp. is most similar to T. brevicornis, but differs by having a smaller, curved penial stylet that has a smaller introvert in relation to stylet size, with about 10 distal crowns of smaller spines. A key to the species of the Temnocephala from chelonians is provided. This study supports the validity of the following characters previously proposed for the taxonomy of the genus Temnocephala: the shape of the sphincters in the female reproductive system, the shape of the penial stylet, and the number, size, and position of spines in the introvert.  相似文献   

10.
The cultivated sunflower (Helianthus annuus) is one of the four most important annual crops in the world grown for its edible oil. Species of the genusHelianthus served as the ancestral stock for the present cultivated sunflower. The wild relatives are a valuable genetic reservoir for improving the crop species. This study examined oil concentration and fatty acid composition in oil of two annualHelianthus species (31 populations) and four perennial species (32 populations) from the prairie provinces of Canada. The highest average oil concentration was observed in annualH. petiolaris with 31.3%. Among the perennials,H. maximiliani Schrad. had the highest average oil concentration with 31.1%.Helianthus tuberosus L. had the highest average palmitic (16:0) acid concentration with 8.0%, while the lowest value was observed inH. petiolaris with 4.0%. The highest average stearic (18:0) acid concentration was found inH. annuus with 2.9%, whileH. petiolaris had the lowest with 2.3%. The highest average oleic acid (18:1) was observed in H. petiolaris (18.4%), and the highest linoleic (18:2) was observed inH. maximiliani (77.4%). The variability within the wild species appears to be sufficient for altering oil and fatty acid characteristics in cultivated sunflower.  相似文献   

11.
Cytoplasmic male sterility (CMS) and its fertility restoration (Rf) genes are critical tools for hybrid seed production to utilize heterosis. In sunflower, CMS PET1 and the associated Rf gene Rf (1) is the only source extensively used in commercial hybrid production. The objective of this research was to develop new sources of CMS and fertility restorers to broaden the genetic diversity of hybrid seed production. We identified a new type of CMS, named as CMS GIG2, from an interspecific cross between Helianthus giganteus accession1934 and H. annuus cv. HA 89. Based on reactions to a set of standard Rf testers, CMS GIG2 is different from all previously reported CMS types, including the CMS GIG1 from another H. giganteus accession. We also identified an Rf gene for CMS GIG2 from wild species H. maximiliani accession 1631. The CMS GIG2 and its restoration gene were introduced into HA 89 background through recurrent backcross and single plant selection techniques. Genetic analysis revealed that the CMS GIG2-Rf system is controlled by a completely dominant gene, named as Rf (4), and the gene additive and dominance effects were estimated as 39.9 and 42.2%, respectively, in the HA 89 background. The gene Rf (4) was mapped onto linkage group 3 with simple sequence repeat (SSR) markers and RFLP-derived STS-marker, and is about 0.9 cM away from the SSR marker ORS1114 based on a segregation population of 933 individuals. The CMS GIG2-Rf (4) system tagged by molecular markers provides an alternative genetic source for hybrid breeding in the sunflower crop.  相似文献   

12.
13.
Ectotherm species are not capable of generating metabolic heat; therefore, they present different strategies for regulating their body temperatures, ranging from a precise degree of thermoregulation to a passive thermoconformity with ambient temperatures. In reptiles, aerial basking is the most common mechanism for gaining heat. However, among aquatic reptiles, such as freshwater turtles, aquatic basking is also frequent. Hydromedusa tectifera is a turtle of exclusively aquatic and nocturnal habits widely distributed in South America. We studied the relationship between body temperature (Tb) of H. tectifera and its habitat, and explored the effects of sex, life stage and body size and mass on Tb. Fieldwork was conducted in two streams of a mountain area of central Argentina. We recorded cloacal temperature, size and mass of 84 turtles. We also determined individuals’ sex and life stage (adult/juvenile). Regarding ambient temperatures, we measured water temperature on the surface (Tsurf) and at depth of turtle capture (Tdepth) and air temperature. Mean Tb was 18.58 °C (Min = 10.20 °C; Max = 25.70 °C). Tsurf and Tdepth were highly correlated. Multi-model analysis using Akaike criterion indicated that Tb was strongly associated with water temperature, whereas air temperature and body size and mass did not show a significant effect. There was also no effect of turtle sex or life stage on Tb. Our results indicate that H. tectifera is a thermoconformer and eurythermal species. A nocturnal pattern of activity and a fully aquatic lifestyle are suggested as determinant factors.  相似文献   

14.
Twenty-eight taxa of Helianthus collected throughout the United States and grown in afield nursery were evaluated for yields of oil, polyphenol hydrocarbon, protein, and ash in above-ground biomass. Hydrocarbons were examined for the presence of rubber, gutta, and waxes. Rubber and gutta were analyzed for weight-average molecular weight (ìw) and molecular weight distribution (MWD). Helianthus ciliaris had the highest oil yield (3.7%) and was analyzed for yield of fatty acids and unsaponifiable matter. Most taxa had low polyphenol yields (<10%), with H. strumosus having the highest (13.9%). Helianthus salicifolius yielded the most hydrocarbon (1.6%) and H. ciliaris had the highest protein content (13.4%). Natural rubber was present in 13 species of wild sunflowers. Helianthus maximiliani had the lowest ìw (29.8 x 103), while H. laevigatus had the highest (73.3 x 103). The MWD of rubber from sunflowers were within the range of those for commercial rubbers. The lower molecular weight rubbers may have potential as plasticizing additives in commercial processing of synthetic polyisoprenes and as hydrocarbon feedstock for a synthetic petroleum industry.  相似文献   

15.
烟台四十里湾浮游动物群落特征及与环境因子的关系   总被引:3,自引:0,他引:3  
2009年3月—2010年12月在烟台四十里湾海域对浮游动物群落结构及其环境因子进行了连续20个航次的综合调查,记录到浮游动物8大类共计64种(类)。浮游动物主要类群为桡足类和浮游幼虫,分别发现22种、18类,占总种(类)数34%、28%;其次为水螅水母类,发现13种,占20%;毛颚动物和栉水母类各发现1种。浮游动物的优势种为中华哲水蚤(Y=0.183)、腹针胸刺水蚤(Y=0.078)、强壮箭虫(Y=0.078)和洪氏纺锤水蚤(Y=0.026)。浮游动物的生态类型主要为温带近岸种和广布性种。四十里湾海域浮游动物群落结构的季节变化较为明显,春、夏、秋、冬四季之间群落结构有显著性差异(P0.05),同一季节内群落结构相似度较高,达55%以上。浮游动物丰度中位值在5月份达到最高(546.3个/m~3);种类数、多样性指数中位值均在8月达到最高,分别为18种、3.20;浮游动物生物量呈现出双峰变化模型,5月份达到第1峰值(中位值870.4 mg/m~3),10月份为第2峰值(中位值362.0 mg/m~3)。浮游动物种类数高值区主要分布在养马岛北部海域,而丰度高值区主要分布在近岸尤其是辛安河口海域。浮游动物种类数及多样性指数与水温、化学需氧量、硅酸盐显著正相关(P0.01),与盐度、溶解氧、无机氮显著负相关(P0.01);水温和盐度是影响浮游动物分布的主要环境因子,其次是硅酸盐、叶绿素a和化学需氧量,活性磷酸盐、溶解氧、透明度以及无机氮对浮游动物分布的影响较小。  相似文献   

16.
长江口及邻近海域浮游动物群落结构及季节变化   总被引:6,自引:0,他引:6  
根据2006—2007年长江口及其邻近海域(29°30'N—32°30'N,120°00'E—127°30'E)150个站位4个季节的调查资料,对长江口海域浮游动物群落结构、种类组成、优势种及其季节变化进行研究。结果表明,长江口及其邻近海域浮游动物群落物种多样性丰富,四季共鉴定浮游动物460种,隶属7个门,246属,此外,另有54类浮游幼体。其中,桡足类是最优势类群,有193种,占41.96%;端足类为第二优势类群,有51种,占11.09%;水螅水母为第三优势类群,有34种,占7.39%。长江口及其邻近海域浮游动物的物种多样性呈现明显季节变化,其特征为:夏季(317种)秋季(309种)春季(230种)冬季(138种)。中华哲水蚤和百陶带箭虫为长江口及其邻近海域的四季优势种。长江口及其邻近海域浮游动物大体可划分为5种生态类群:近岸低盐类群、广温广盐类群、低温高盐类群、高温广盐类群和高温高盐类群。结合同步调查的水文和水化学数据,进行浮游动物群落丰度与环境因子的相关分析表明:盐度是影响长江口及其邻近海域的浮游动物群落丰度的主要环境因子。  相似文献   

17.
18.
莱州湾金城海域浮游动物群落结构及与环境因子的关系   总被引:15,自引:0,他引:15  
于2009年和2010年3—12月在莱州湾金城海域对浮游动物群落结构及其环境因子进行了连续20个月份的综合调查,共记录到浮游动物75种,分属14个不同大类。浮游动物以桡足类和浮游幼虫居多,分别鉴定出22种、20类,占种类总数的29.3%、26.7%,其次为水螅水母类,鉴定出11种,端足类、被囊动物、腹足类和栉水母类分别鉴定出6种、4种、4种、2种,其它枝角类、毛颚动物、等足类、糠虾类、磷虾类以及钵水母类各鉴定出1种。主要优势种为强壮箭虫(优势度Y=0.24)、中华哲水蚤(Y=0.13)、墨氏胸刺水蚤(Y=0.07)、以及洪氏纺锤水蚤(Y=0.02)。2009年与2010年浮游动物群落结构的变化趋势比较稳定,同一季节群落结构相似度达到40%以上。浮游动物丰度分别在2009年及2010年的5月份达到最高值951.65个/m3、1348.14个/m3。种类数分别在2009年9月和2010年6月达到最高值48种、40种。多样性指数分别在2009年10月及2010年5月达到最高值2.6、2.7,呈现明显的季节变化特征。典范对应分析(Canonical correspondence analysis,CCA)显示,水温和盐度是影响浮游动物群落结构最主要的影响因子,水温与浮游动物种类数的相关系数达到0.87(P0.01)。盐度与浮游动物数量的相关系数为0.484(P0.05)。透明度、化学耗氧量、pH、叶绿素及总氮总磷等环境参数对浮游动物群落结构的影响较弱。  相似文献   

19.
Materials from six complex trawl surveys conducted by the TINRO-Center in the upper epipelagic zone of the Western Bering Sea during the summer-fall seasons from 2002 through 2006 were used as the basis of this paper. The overall biomass (and abundance) of jellyfish increased from 0.6–0.8 million t (1.1–1.8 billion individuals) in the summer up to 0.9–1.7 million t (4.4–4.8 billion individuals) in fall. Scyphomedusa Chrysaora melanaster and the Hydromedusa Aequorea forskalea made up the major part of the jellyfish biomass (67–97%). Their distribution varied significantly. A. forskalea aggregated mainly in the deepwater part of the Bering Sea. Ch. melanaster was widely dispersed across the entire area of the investigations and formed the most considerable aggregations in the Anadyr-Navarin area. In the fall of 2006 the diet of jellyfish generally consisted of plankton organisms (copepods, euphausiids, amphipods, pteropods, chaetognaths, ostracods, and larval decapods). However, Ch. melanaster had a greater portion of fish and larval squid in its diet.  相似文献   

20.
The Tripterygiidae of New Caledonia are revised and their zoogeographical relationships discussed. A total of 27 species is recognized from the territory; three species are recorded from New Caledonia for the first time [Enneapterygius howensis Fricke, 1997; Enneapterygius rhabdotus Fricke, 1994; Helcogramma trigloides (Bleeker, 1858)]. From Grande Terre, 26 species are known, with four species recorded for the first time. Seven species occur at the Ile des Pins (all new records); from the Chesterfield Islands, six species of tripterygiid fishes have been recorded; and from the Loyalty Islands, 17 species are known, with three species recorded from the island group for the first time: 15 species from Ouvéa, 11 species from Lifou (eight new records) and five species from Maré (three new records).  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号