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.
Abstract. As needlefishes (Belonidae) grow, their jaws pass through a "halfbeak" stage that resembles the adult jaw condition of the closely related family of halfbeaks (Hemiramphidae). Based on this pattern, some authors have suggested that halfbeaks are "developmentally arrested" or paedomorphic needlefish derivatives, whereas others have supported the notion that needlefishes are descended from halfbeak-like ancestors and that needlefish ontogeny thereby recapitulates phylogeny. To test these ideas and to better understand evolutionary changes in jaw ontogeny, phylogenetic relationships among genera of needlefishes, sauries (Scomberesocidae), halfbeaks, and flyingfishes (Exocoetidae) were assessed using mitochondrial (cytochrome b and 16S), nuclear (Tmo-4C4), and morphological characters. The resultant tree provides several novel taxonomic findings: (1) flyingfishes appear to be nested within halfbeaks; (2) sauries appear to be nested within needlefishes; and (3) the Indo-West Pacific freshwater halfbeaks appear to be most closely related to the needlefish/saury clade. The structure of the tree falsifies the idea that halfbeaks are paedomorphic needlefishes. Instead, halfbeaks are basal relative to needlefishes, fitting the pattern predicted by the hypothesis of recapitulation. I discuss limitations to phylogenetic perspectives on recapitulation based on discrete character data by comparing aspects of von Baerian and Haeckelian views of the relation between ontogeny and phylogeny.  相似文献   

2.
A comparative cytogenetic analysis was carried out on four Hylinae tree frogs from Brazil ((Aparasphenodon brunoi, Corythomantis greeningi, Osteocephalus langsdorffii, and Scinax fuscovarius) using Giemsa staining, BrdU replication banding, Ag-NOR staining, C-banding, DAPI and CMA(3) fluorochrome staining, and fluorescence in situ hybridization (FISH) with an rDNA probe. All the species share closely similar 2n = 24 karyotypes, almost indistinguishable by standard staining. The technique of BrdU incorporation allowed the identification of each pair of homologs and the establishment of extensive homeology for the great majority of the chromosomes, mainly of A. brunoi, C. greeningi, and O. langsdorffii. Despite highly conserved replication banding patterns, the use of the other banding techniques disclosed some minor differences, which reinforces the importance of extensive cytogenetic analyses for the karyotypic characterization of Anuran species. The present cytogenetic data confirm the closer proximity of A. brunoi, C. greeningi, and O. langsdorffii, whereas S. fuscovarius is phylogenetically more distant.  相似文献   

3.
Belonidae are unusual in that they are carnivorous but lack a stomach and have a straight, short gut. To develop a functional morphological model for this unusual system the gut contents and alimentary tract morphology of Tylosurus gavialoides and Strongylura leiura ferox were investigated. The posterior orientation of the majority of the pharyngeal teeth supports the swallowing of whole large prey, but not their mastication. Mucogenic cells are abundant in the mucosa lining, particularly the esophagus, and their secretions are likely to protect the gut lining from damage while lubricating passage of the prey. Esophagus, anterior intestine, posterior intestine, and rectum all have highly reticulate mucosae. The anterior three gut sections are distensible to accommodate the passage of prey. However, following ingestion large prey are passed to the highly distensible posterior intestine where they rest head first against the ileorectal valve. Alimentary pH ranges from neutral to weakly acidic. Fish prey is digested head first with the head being largely digested while the remainder of the body is still intact. The nondistensibility of the rectum and the small aperture provided by the ileorectal valve suggest the products of intestinal digestion are either small particulates or fluids that pass into rectum where they are absorbed. J. Morphol. 2009. © 2009 Wiley‐Liss, Inc.  相似文献   

4.
Scott A. Mori 《Brittonia》1981,33(3):466-472
Eschweilera tetrapetala Mori andE. alvimii Mori are described and compared withE. compressa (Vellozo) Miers, the only other species of this genus known to have four petals. It is concluded that this small group of species probably evolved from a common ancestor whose range was fragmented by climatic and vegetational changes in the Pleistocene. The distributions ofE. compressa andE. alvimii support the hypothesis that moist forest refuges existed around Rio de Janeiro and southern Bahia/northern Espírito Santo throughout the Pleistocene.  相似文献   

5.
Hwang DS  Kim BM  Au DW  Lee JS 《Mitochondrial DNA》2012,23(4):308-309
The complete mitochondrial genome was obtained from the assembled genome data sequenced by next-generation sequencer from the marine medaka Oryzias melastigma. The mitochondrial genome sequence was 16,864 bp in size, and the gene order and contents were identical with those of previously reported fish mitochondrial genomes. Of 13 protein-coding genes (PCGs), 4 genes (CO3, ND3, ND4, and Cytb) had incomplete stop codons. The base composition of O. melastigma mitogenome showed high A+T (59.65%) and anti-G bias (8.73%) on the 3rd position of PCGs.  相似文献   

6.
7.
Two new species of Petunia (Solanaceae) from southern Brazil   总被引:1,自引:0,他引:1  
Two new species of Petunia Jussieu from Santa Catarina and Rio Grande do Sul states in Brazil are described and compared with the other seven specieS. A key and synopsis of all the species of Petunia are provided  相似文献   

8.
A new species of the megaspiline genus Dendrocerus Ratzeburg is described and figured. Dendrocerus riograndensissp. n., is known from a series of males from the central region of Rio Grande do Sul, Brazil, and were captured with Malaise traps from an agricultural tobacco field.  相似文献   

9.
Rewardless kettle‐trap flowers Cypripedium yunnanense and C. flavum were watched for pollinators during 73 and 101 man‐hours, respectively, in north‐west Yunnan at 3490–3590 m a.s.l. They differ from typical Cypripedium, such as C. calceolus, in having a broad infolded flap of the lip extending all around the entrance of the pouch (instead of being restricted to the vicinity of the staminode) and in the flap not being slippery. Cypripedium yunnanense is pollinated by Lasioglossum zonulum euronotum (Halictidae), and C. flavum is pollinated by Andrena orchidea and Andrena sp. (Andrenidae, two of nine new hymenopterans discovered at the sites). The bees do not inadvertently fall into the trap by slipping (as often occurs in other slipper orchids), but enter it by crawling down the flap in full control of their movements. No natural hybrids between the two orchids are known, although they occur in close‐by or mixed stands, are co‐flowering and size compatible with regard to their pollinators, and produce fruits following manual cross‐pollination in situ. Analyses of the (non‐Cypripedium) pollen carried indicate that: (1) the two andrenids are probably oligolectic; (2) the andrenids and the halictid do not share the same flower species; and (3) the halictid is polylectic. Points (1) and (2) are probable reasons for the lack of hybrids. The other reason why Lasioglossum zonulum euronotum does not visit C. flavum despite being polylectic may be the flower's odour; cases of discrimination of closely related flowers by polylectic Lasioglossum have been reported elsewhere. Blow flies Calliphora vomitoria and Calliphora pattoni (Calliphoridae) also enter the orchids, some smearing themselves with pollen, yet they are not pollinators. They are too large to leave by the exit and die imprisoned. However, they may be accidental pollinators of the rather larger C. tibeticum present at the sites. Such accidental pollinators probably play an important role in the evolution of new pollination syndromes. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 156 , 51–64.  相似文献   

10.
Phyllostomidae comprises the most diverse family of neotropical bats, its wide range of morphological features leading to uncertainty regarding phylogenetic relationships. Seeing that cytogenetics is one of the fields capable of providing support for currently adopted classifications through the use of several markers, a comparative analysis between two Phyllostomidae species was undertaken in the present study, with a view to supplying datasets for the further establishment of Phyllostomidae evolutionary relationships. Karyotypes of Lonchorhina aurita (2n = 32; FN = 60) and Trachops cirrhosus (2n = 30; FN = 56) were analyzed by G- and C-banding, silver nitrate staining (Ag-NOR) and base-specific fluorochromes. Chromosomal data obtained for both species are in agreement with those previously described, except for X chromosome morphology in T. cirrhosus, hence indicating chromosomal geographical variation in this species. A comparison of G-banding permitted the identification of homeologies in nearly all the chromosomes. Furthermore, C-banding and Ag-NOR patterns were comparable to what has already been observed in the family. In both species CMA(3) /DA/DAPI staining revealed an R-banding-like pattern with CMA (3) , whereas DAPI showed uniform staining in all the chromosomes. Fluorochrome staining patterns for pericentromeric constitutive heterochromatin (CH) regions, as well as for nucleolar organizing regions (NORs), indicated heterogeneity regarding these sequences among Phyllostomidae species.  相似文献   

11.
In the course of monographic work in Myrtaceae it has become evident thatEugenia prismatica cannot be accommodated within any existing genus in the family. Therefore, a new genus,Curitiba, is described to contain it and the new combinationCuritiba prismatica is made.Curitiba is diagnosed by a combination of 4-angled hypanthia and fruits, ovules radiating from a central protruding placenta, and seed coats with wavy rows of papillae. A key is provided to distinguishCuritiba from the Caribbean and Mesoamerican genusMosiera, where the species also had been placed before this transfer, and from other 4-merous genera in Brazil of subtribe Myrtinae. In the Atlantic Forest of Brazil where the family Myrtaceae is one of the most species rich and ecologically important plant families, the discovery ofCuritiba reveals a unique evolutionary lineage, highlights the endemism present in the Atlantic Forest, and underscores, the urgent need for conservation of this rapidly disappearing and highly endangered biome.  相似文献   

12.
A new species of Taeniastrotos is described from an ariid host, Cathrops spixii, caught in southern Brazil. It is the first member of the genus to be recorded from the Atlantic Ocean and can be distinguished from its four known congeners by the setation of the terminal endopodal segment of the fourth leg.  相似文献   

13.
Toarcian (Lower Jurassic) argillaceous-marly sediments of southern France (Causses) and east-central Spain (Barranco de la Puta section) were deposited in mid to lower shelf settings. They contain a low to moderately diverse, autochthonous fauna of benthic macroinvertebrates dominated by bivalves and gastropods, in the case of the Causses, and by bivalves and brachiopods in the Barranco de la Puta section. Five benthic associations are recognized at the latter locality and four at the former. In the Causses, low species diversity, evidence of seasonal mass mortality, presence of the opportunistic bivalve Parvamussium pumilum, local dominance of the soft bottom coral Thecocyathus mactrus and the dark-grey, fine-grained sediment point to high rates of sedimentation, high turbidity, intermittently lowered oxygen values and soft to soupy substrate conditions. These factors, together with eutrophic water masses, were the main environmental parameters governing faunal distribution. Soupy substrate conditions are thought to be largely biologically produced by the activity of infaunal depositfeeders, chiefly nuculoid bivalves. In the Barranco de la Puta section, abundant brachiopods, higher carbonate content of the sediment, and evidence of intermittent in-situ reworking and winnowing point to an influence of storm-induced currents, a shallower depositional depth, lower turbidity, a lower rate of sedimentation, and a somewhat firmer substrate. As a consequence, the fauna is largely dominated by epifaunal suspension-feeders. Compared with maximum and average sizes from elsewhere in the Jurassic, most bivalve species are distinctly smaller, a feature interpreted as stunting. Brachiopods, in contrast, reach normal size. The lack of nuculids, scarcity of deposit-feeders in general, and stunting are interpreted as evidence of an oligotrophic environment. Lowered oxygen conditions appear to have played only a very limited role in shaping the distribution pattern. Many of the differences between both areas can be explained by the different trophic regimes that reflect considerably higher run-off and consequently higher input of terrigenous sediment and dissolved nutrients to the basin in the case of the Causses. This in turn is thought to possibly reflect differences in regional climate; humid in southern France and more arid in eastcentral Spain.  相似文献   

14.
The grasshopper species Orthoscapheus rufipes and Eujivarus fusiformis were analyzed using several cytogenetic techniques. The karyotype of O. rufipes, described here for the first time, had a diploid number of 2n = 23, whereas E. fusiformis had a karyotype with 2n = 21. The two species showed the same mechanism of sex determination (XO type) but differed in chromosome morphology. Pericentromeric blocks of constitutive heterochromatin (CH) were detected in the chromosome complement of both species. CMA(3)/DA/DAPI staining revealed CMA(3)-positive blocks in CH regions in four autosomal bivalents of O. rufipes and in two of E. fusiformis. The location of active NORs differed between the two species, occurring in bivalents M(6) and S(9) of O. rufipes and M(6) and M(7) of E. fusiformsi. The rDNA sites revealed by FISH coincided with the number and position of the active NORs detected by AgNO(3) staining. The variability in chromosomal markers accounted for the karyotype differentiation observed in the tribe Abracrini.  相似文献   

15.
Alves AL  Oliveira C  Foresti F 《Genetica》2005,124(2-3):127-136
The family Loricariidae with about 690 species divided into six subfamilies, is one of the world’s largest fish families. Recent studies have shown the existence of several problems in the definition of natural groups in the family, which has made the characterization of the subfamilies and even of some genera quite difficult. With the main objective of contributing for a better understanding of the relationships between loricariids, cytogenetic analysis were conducted with two species of Neoplecostominae and nine species of Hypostominae that, according to morphological and molecular data, may belong to a new monophyletic unit. The results obtained showed a marked chromosomal conservation with the presence of 2n = 54 chromosomes and single interstitial Ag-NORs in all species analyzed. Considering that Neoplecostominae is the primitive sister-group of all other loricariids, with exception of Lithogeneinae, this karyotypic structure may represent the primitive condition for the family Loricariidae. The cytogenetic characteristics partaken by the species of Neoplecostominae and Hypostominae analyzed in the present study reinforce the hypothesis that the species of both these subfamilies might belong to a natural group.  相似文献   

16.
The pollination process and breeding system of the sympatric Habenaria johannensis, H. macronectar, H. megapotamensis and H. montevidensis was documented for native populations from Rio Grande do Sul, Brazil. All species investigated offer a nectar reward (mean values of total sugars ranging from 18 to 26%) concealed in a spur. Habenaria montevidensis is pollinated by butterflies (Hesperiidae, especially of the genus Urbanus) that carry pollinaria on their eyes; the other three species are pollinated by Sphingidae. Habenaria johannensis is pollinated by the moths Manduca rustica and M. sexta that carry the pollinaria at the base of the proboscis. Habenaria macronectar is pollinated by the moths Eumorpha labrusca and M. cf. lucetius, and these bear pollinaria between the palpi. Habenaria megapotamensis is pollinated by moths of M. cf. lucetius that bear the pollinaria on the proboscis. All species studied are self‐compatible, but pollinator dependent. They also displayed high reproductive success (ranging from 69.48 to 97.40%) and male efficiency factors slightly higher than 1, suggesting that at least one flower was pollinated for each flower acting as pollen donor. At the study sites, the investigated Habenaria spp. are isolated (in terms of pollination) by a set of factors that includes differing floral morphologies, different pollinators and/or different pollinarium placement on the pollinator. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, ??, ??–??.  相似文献   

17.
18.
Species of Cestrum L. (Solanaceae) exhibit large variability in the accumulation of repetitive DNA, although their species possess a stable diploid number with 2n = 16. In this study, we used chromosome banding and fluorescence in situ hybridization (FISH) to characterize the karyotypes and populations of two species, Cestrum nocturnum L. and C. mariquitense Kunth. We also performed a karyotype comparison using 16 idiograms, of which 4 were developed in this study and 12 were obtained from the literature. Cestrum nocturnum displayed more bands than C. mariquitense, but the latter exhibited greater interpopulational variation in the band patterns. There was a tendency for large bands to be located at intercalary/terminal regions and for small bands to be located at intermediate/proximal regions. The idiogram comparison revealed a large variation in the amount, distribution, and size of heterochromatic bands. FISH with rDNA probes revealed stability in the number and location of 5S sites, while 45S was more variable in size and number of sites. Although 45S rDNA always appeared in the subterminal regions, this DNA family exhibited a mobility among chromosome pairs. These data highlight the dynamic of repetitive DNA families in these genomes, as well as the contribution for intra- and interspecific karyotype differentiation in Cestrum.  相似文献   

19.
Petunia bajeensis and P. riograndensis, two new species from southern Rio Grande do Sul, Brazil are described, and their morphological distinction from related species and features of their habitats are discussed.  相似文献   

20.
In recent years, the progressive decline in populations of anuran amphibians has left many species increasingly vulnerable to extinction. The potential role of morphological abnormalities as a mechanism of this decline has attracted attention in many recent studies. We investigated the occurrence and frequency of morphological abnormalities in anurans from northern of the state of Rio Grande do Sul, Brazil. We sampled 1674 individuals from three different environments – forest, farmland and peri‐urban areas – between 2001 and 2017. We recorded 89 individuals with morphological abnormalities, with 12 different types of abnormality in 19 anuran species. We recorded nine types of abnormality in forest and seven in the farmland, with brachydactyly being the most common abnormality in both areas. Only three abnormalities were recorded in the peri‐urban area, and all three were equally frequent. Studies of morphological alterations provide important insights into the potential effects of environmental impacts on anuran populations and may be essential for the planning of effective conservation strategies.  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