Molecular systematics and evolutionary history of catenotaeniid cestodes (Cyclophyllidea)

Phylogenetic relationships, evolutionary history and systematics of tapeworms of the family Catenotaeniidae were studied using nucleotide sequences of the partial 28S nuclear rDNA (ca. 1,500 bp) and mitochondrial 12S–16S DNA (ca. 820 bp) genes. The tapeworm material consists of 29 species, including type species of the genera Catenotaenia Janicki, 1904, Catenotaenioides Haukisalmi, Hardman and Henttonen, 2010, Pseudocatenotaenia Tenora, Mas‐Coma, Murai and Feliu, 1980, Skrjabinotaenia Akhumyan, 1946, Meggittina Lynsdale, 1953, and Hemicatenotaenia Tenora, 1977. The basal phylogenetic structure of the Catenotaeniidae remains unresolved, but it is shown that most of the catenotaeniids in Eurasia and Africa comprise a large clade represented by species of Catenotaenia, Catenotaenioides, Skrjabinotaenia and Meggittina, parasitizing murid, cricetid, nesomyid and sciurid rodents. The results suggest that the divergence and early radiation of this clade have occurred in murid rodents (represented by Apodemus spp. and Mus musculus in the present material) in western Eurasia, followed by colonization of Africa, most likely independently of the colonization of their murid hosts between these continents. There is very little evidence of cophylogeny between hosts and parasites, suggesting that host transfers have played a major role in the divergence of catenotaeniids. In Africa, catenotaeniids have radiated in other murid and nesomyid rodents, and later colonized Madagascar and recolonized Eurasia. The results also show that the subfamily Skrjabinotaeniinae (including Skrjabinotaenia and Meggittina) is monophyletic, but the Catenotaeniinae (including Catenotaenia, Catenotaenioides, Pseudocatenotaenia and Hemicatenotaenia) is clearly non‐monophyletic. In addition, the genera Catenotaenia and Skrjabinotaenia were both found to be non‐monophyletic. Based on the phylogenetic and morphological evidence, several taxonomical changes, mainly new combinations, are proposed. Overall, the present results suggest that the family Catenotaeniidae is in need of major systematic revision.     

Molecular systematics and global phylogeography of angel sharks (genus Squatina)

Angel sharks of the genus Squatina represent a group comprising 22 extant benthic species inhabiting continental shelves and upper slopes. In the present study, a comprehensive phylogenetic reconstruction of 17 Squatina species based on two mitochondrial markers (COI and 16S rRNA) is provided. The phylogenetic reconstructions are used to test biogeographic patterns. In addition, a molecular clock analysis is conducted to estimate divergence times of the emerged clades. All analyses show Squatina to be monophyletic. Four geographic clades are recognized, of which the Europe–North Africa–Asia clade is probably a result of the Tethys Sea closure. A second sister group relationship emerged in the analyses, including S. californica (eastern North Pacific) and S. dumeril (western North Atlantic), probably related to the rise of the Panamanian isthmus. The molecular clock analysis show that both lineage divergences coincide with the estimated time of these two geological events.     

Molecular systematics and phylogeography of Amazonian poison frogs of the genus Dendrobates

The study of Amazonian biodiversity requires detailed knowledge of the phylogenetic relationships of closely related taxa distributed across Amazonia. The Amazonian poison frogs of the genus Dendrobates have undergone many taxonomic revisions, but the phylogenetic relationships within this group remain poorly understood. Most previous classifications were based on morphology and skin toxin analyses, with limited use of DNA sequence data. Using mtDNA sequence data from four gene regions (cytochrome b, cytochrome oxidase I, 16S rRNA, and 12S rRNA), we present a molecular phylogenetic analysis of the evolutionary relationships within a representative group of Amazonian Dendrobates. We use the resulting phylogenetic hypothesis to investigate different biogeographic hypotheses concerning genetic divergence and species diversity in Amazonia. The results of the analysis support the presence of ancient paleogeographic barriers to gene flow between eastern and western Amazonia, and indicate substantial genetic divergence between species found in the northern and southern regions of western Amazonia.     

Molecular systematics,historical ecology,and phylogeography of Halimeda (Bryopsidales)

Halimeda (Bryopsidales), a genus of calcified, segmented green seaweeds, abounds in reefs and lagoons throughout the tropics. To investigate phylogenetic, phylogeographic, and historic ecological relationships of the genus, the nuclear rDNA including the SSU and both ITS regions were sequenced. A maximum likelihood tree revealed the following: (1) there were anatomical and morphological synapomorphies for five well-supported lineages; (2) the last common ancestor of one lineage invaded sandy substrata; those of two other lineages established in wave-affected habitats, whereas the cenancestor of the remaining two lineages occupied sheltered rocky slopes. Yet, several species adapted to new habitats subsequently, resulting in several cases of convergence; (3) all lineages separated into Atlantic and Indo-Pacific daughters, likely resulting from the rise of the Panamanian Isthmus. Each daughter pair gave rise to additional convergent species in similar habitats in different oceans; (4) Halimeda opuntia, the only monophyletic pantropical species detected so far, dispersed from the Indo-Pacific into the Atlantic well after the closure event; (5) minor SSU-sequence differences across species and phylogeographic patterns of vicariance indicated a relatively recent diversification of the extant diversity. Cretaceous and Early Tertiary fossil look-alikes of modern species must then have resulted from iterative convergence.     

扩张莫尼茨绦虫(圆叶目:裸头科)节间腺的超微结构及组织化学

用光学显微镜和透射电子显微镜观察了扩张莫尼茨绦虫节间腺形成过程的精细结构及一些组化变化。结果表明：节间腺是扩张莫尼茨绦虫皮层的特化部分,由节片后缘的皮层及其邻近细胞体向绦虫实质组织中陷入开始其形成过程,随着虫体发育的进行,新的陷入不断形成,原陷入的部分不断脱离皮层形成簇状腺体结构。节间腺的数目随着体节的发育不断增加,幼节中仅有少数几个(6～9个),而远端的孕节中多于100个。电镜下可见腺细胞体由细胞质管与腺皮层相联,簇状腺体结构为一合胞体形态,腺细胞体围绕并开口于椭球体或不规则形状的皮层腔中。离腺皮层远的腺细胞体电子密度高并含有与腺皮层相应的典型分泌颗粒,而靠近腺皮层的腺细胞体电子密度低,所含分泌颗粒较少。扩张莫尼茨绦虫节间腺的组化性质尚不完全清楚。糖与蛋白质等组化结果不稳定,随染液pH值及染色时间的变化等多种因素而改变。基于我们的研究及其他研究者的观察表明,节间腺可能参与外源基质形成虫卵的转运,同时他们可能在虫体节片脱落及虫卵溢出时起作用。     

Molecular systematics and time-scale for the evolution of Timarcha, a leaf-beetle genus with a disjunct Holarctic distribution

In recent years we have investigated the evolution of the Holarctic leaf-beetle genus Timarcha using molecular approaches, but to date several important questions remained unanswered, including its systematic arrangement in a temporal context, or the phylogenetic placement of the Nearctic taxa. Here I present a reanalysis of available genetic data together with newly generated data for key taxa (markers 16S rDNA, CO2, ITS-2, and 18S rDNA), including the Nearctic species (subgenus Americanotimarcha), using direct optimization-based phylogenetic reconstructions. Lineage ages are estimated using maximum likelihood branch-length estimates and the molecular clock calibration derived from several presumed vicariance events in the Mediterranean. Phylogenetic analyses and 18S rDNA divergences suggest the ancient divergence of the Nearctic and Palaearctic lineages, related to the North Atlantic opening in the middle Eocene. The diversification of the Palaearctic Timarcha seems closely related to the geological evolution of the Mediterranean area during the Tertiary, with Pleistocenic climate changes affecting species ranges and lineage extinction, but not resulting in extensive speciation.     

Demographic attributes of dispersing southern bog lemmings (Synaptomys cooperi) in eastern Kansas

Summary Demographic attributes of southern bog lemmings colonizing two removal grids were compared with those of residents on neighboring control grids over a two year period in eastern Kansas. There was a positive association between the number of lemmings colonizing the removal grids and density of the control grids. Overall, 41% of the losses from the two control grids was accounted for by dispersal. The following differences were observed comparing residents with dispersers: 1) a greater proportion of males colonized the removal grids, 2) a lower percentage of adult females colonizing the removal grids were in breeding condition, whereas the reverse was true for subadult females, and 3) a greater proportion of subadults colonized the removal grids. These results are consistent with those obtained for other microtine species.I don't understand, said the scientist, why you lemmings all rush down to the sea and drown yourselves. How curious, said the lemming. The one thing I don't understand is why you human beings don't — from Intervie with a Lemming by James Thurber.     

扩张莫尼茨绦虫(圆叶目:裸头科)精细胞分化、精子形成及精子形态

本项研究应用光学显微镜、扫描和透射电子显微镜,观察了扩张莫尼茨绦虫的精细胞分化、精子形成全过程及精子的精细结构。扩张莫尼茨绦虫的精细胞分化过程为：1)初级精原细胞主要发生于幼节的睾丸滤泡中;2)次级精原细胞发生不完全分裂形成16个细胞一簇的初级精母细胞群,以共同的中央细胞质相连;3)初级精母细胞的特征为细胞核中出现联会复合体结构;4)紧接着的第二次成熟分裂,产生64个由中央细胞质相连的细胞核较小的精细胞。精子形成始于精细胞中分化区的形成,成熟精子缺乏线粒体,具有质膜和冠状体、1—4个领域排布的质膜下皮层微管,细胞质中存在电子致密的颗粒状物质,具一个不规则形态的细胞核,具有“9 1”类型的轴丝构造,缺乏轴丝周围鞘。从精子的纵切面上可将精子区分为5个区段(Ⅰ一Ⅴ区)。在精子形成过程中,中心粒基部出现螺旋形小根结构在寄生虫中为首次报导;成熟精子具有游离鞭毛,在绦虫中为首次发现[动物学报49(3)：370—379,2003]。     

Brachylepis gen. n.--a new genus of cestodes (Cyclophyllidea: Hymenolepididae) from shrews in Siberia and the Far East

A new genus Brachylepis gen. n. hymenolepididean cestodes associated with common shrews (Sorex) in Siberia and Russian Far East is created. These genus includes three species removed from the genus Mathevolepis: Brachylepis morosovi (Karpenko, 1994) comb. n. (type species), B. sorextscherskii (Morosov, 1957) comb. n. and B. triovaria Karpenko, 1990) comb. n. The new genus is characterized by the gradual strobila with a little number of segments, unarmed scolex with apical glandular organ, by lack of internal seminal vesicle and differential seminal receptacle, by form of uterus as horse shoe in young worms and buble-like in mature worms. A tendency of inverse proportional dependence between the number of uterus segments in the strobila and the number of hexacanths in the uterus has been noticed. The table of differential characters for the species of the genus Brachylepis is proposed.     

Molecular systematics and phylogeography of the cryptic species complex Baetis rhodani (Ephemeroptera, Baetidae)

Genetic studies have highlighted cryptic diversity in many well-known taxa including aquatic insects, with the general implication that there are more species than are currently recognised. Baetis rhodani Pictet are among the most widespread, abundant and ecologically important of all European mayflies (Ephemeroptera), and used widely as biological indicators of stream quality. Traditional taxonomy and systematics have never fully resolved differences among suspected cryptic species in the B. rhodani complex because morphological characters alone do not allow reliable distinction. This is particularly true among larvae, the life-stage used most widely in monitoring. Here, we assess the molecular diversity of this complex in one of the largest such studies of cryptic species in the order Ephemeroptera to date. Phylogenies were constructed using data from the mitochondrial cytochrome oxidase subunit I (COI) gene. Two monophyletic groups were recovered consisting of one major haplogroup and a second clade of 6 smaller but distinct haplogroups. Haplogroup divergence ranged from 0.2-3% (within) to 8-19% (among) with the latter values surpassing maxima typically reported for other insects, and provides strong evidence for cryptic species in the B. rhodani complex. The taxonomic status of these seven haplogroups remains undefined. Their distributions across Western Europe reveal no obvious geographic pattern, suggesting widespread diffusion of genetic lineages since the last glacial maximum. The implications of these findings are far-reaching given the ecological and bioindicator significance of what now appears to be several taxa.     

Molecular systematics and evolutionary history of the genus Carabus (Col. Carabidae)

Despite the number of evolutionary, ecological and conservation studies that are conducted on Carabus, the global evolutionary history of the genus remains poorly understood. Here, we analysed 7.5 kilobases of DNA sequence data (six mitochondrial and four nuclear genes) from a worldwide sample of 45% of the known subgenera (99 species and 14 subspecies). We compared the nuclear and mitochondrial phylogenies obtained from Maximum likelihood and Bayesian analyses through topological tests of congruence and dating analyses. Our results mostly corroborate the monophyly of the morphological subgroups of Carabus. However, current morphological and molecular data appear unable to accurately infer the deep branchings within the genus. We show that Carabus originated ca. 16.7-25.1Ma, approximately 25Myr later than previously estimated. Major groups of Carabus are subdivided into clades that diverged from each other in a relatively short period of time around 10Ma (6.6-14.8). This time frame suggests that the present-day distribution of Carabus subgroups may be explained by isolation resulting from Eurasian forest fragmentation brought on by Miocene climate changes and by mountain orogenesis. Finally, we highlight several conflicts between mitochondrial and nuclear topologies that may be explained by mitochondrial introgression.     

Molecular phylogenetics,character evolution and systematics of the genus Micranthes (Saxifragaceae)

With c. 85 species, the genus Micranthes is among the larger genera of the Saxifragaceae. It is only distantly related to the morphologically similar genus Saxifraga, in which it has frequently been included as Saxifraga section Micranthes. To study the molecular evolution of Micranthes, we analysed nuclear ribosomal (internal transcribed spacer, ITS) and plastid (trnL–trnF) DNA sequences in a comprehensive set of taxa comprising c. 75% of the species. The molecular phylogenetic tree from the combined dataset revealed eight well‐supported clades of Micranthes. These clades agree in part with previously acknowledged subsections or series of Saxifraga section Micranthes. As these eight groups can also be delineated morphologically, we suggest that they should be recognized as sections of Micranthes. New relationships were also detected for some species and species groups, e.g. section Davuricae sister to sections Intermediae and Merkianae, and M. micranthidifolia as a member of section Micranthes. Species proposed to be excluded from the genus Micranthes for morphological reasons were resolved in the molecular tree in Saxifraga. Many morphological characters surveyed were homoplasious to varying extents. Micromorphological characters support comparatively well the clades in the phylogenetic tree. An updated nomenclature and a taxonomic conspectus of sections and species of Micranthes are provided. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178 , 47–66.     

Molecular evolution of Holarctic martens (genus Martes,Mammalia: Carnivora: Mustelidae)

The Bering Land Bridge has served as a major corridor of interchange between the northern continents for many organisms. We investigated the phylogeny of all extant species of Martes (except for Martes gwatkinsi from India) to infer evolutionary relationships and characterize the extent of trans-Beringian movements. Analyses of complete sequences of the mitochondrial cytochrome b gene and partial sequences of the nuclear aldolase C gene (241bp) suggested that the genus Martes may be paraphyletic with respect to Gulo gulo. These data supported the fossil record's indication that early radiations gave rise to two subgenera (Pekania and Charronia) and that a more recent, possibly rapid, radiation gave rise to species of the third subgenus (Martes). Two colonizations of North America are evident, one by members of the subgenus Pekania and another by member of the subgenus Martes. Contrary to hypotheses based on morphological evidence, the "americana" and "caurina" subspecies groups of Martes americana are not the result of independent colonizations of North America. The phylogenetic analyses of cytochrome b data were consistent with the recognition of these subspecies groups as monophyletic clades; however, variation in the aldolase C sequences indicated that these generally parapatric groups may interbreed in a region of limited geographic overlap.     

Molecular systematics of the genus Allodontichthys (Cyprinodontiformes: Goodeidae)

Phylogenetic analyses of cytochrome c oxidasesubunit I (627bp) and mitochondrial controlregion (338bp aligned) sequences for all knownspecies of Allodontichthys wereperformed. Allodontichthys was recoveredas monophyletic, and A. hubbsi wassupported as the most primitive member of thegenus in all analyses. Combined-data analysessuggest that A. polylepis is sister to aclade comprising A. tamazulae and A. zonistius; however, a strict consensus of COIand control region cladograms results in acollapse of this node. The two species thatare broadly sympatric, A. hubbsi and A. tamazulae, are not sister taxa.Allodontichthys was found the sistergroup of a clade including Ilyodon andXenotaenia. These three genera are theonly goodeids to occupy high-gradient riversystems. Ilyodon and Allodontichthys share similar distributions;however, Allodontichthys exhibits greaterthan an order of magnitude more geneticvariation in COI than Ilyodon incomparisons of individuals from the samelocalities in the Ameca and Armeria drainagesystems. This is interpreted to mean Allodontichthys arrived in some westerndrainages significantly before Ilyodon.The Rio Coahuayana appears to be the center oforigin of the genus Allodontichthys. This river basin contains the most primitivemember of the genus, and appears to haveconnected with the Mesa Central, the center of endemism of the Goodeidae. A calibrated rateof molecular change in COI reveals Allodontichthys began diverging approximately6.2 million years ago (mya). Remainingspeciation in the group appears to haveoccurred about 2.7 to 3.3 mya. The hypothesisthat a hard polytomy comprising A. zonistius, A. polylepis, and A. tamazulae could be explained by speciation ofA. polylepis and A. tamazulae fromdifferent A. zonistius ancestors ispresented. Stream capture is evident but notfrequent in the history of Allodontichthys, and speciation does notclearly correlate with documented geologicactivity of the Mexican Transvolcanic Belt.     

Molecular systematics of the fern genus Hymenophyllum s.l. (Hymenophyllaceae) based on chloroplastic coding and noncoding regions

We investigated the phylogenetic relationships of the filmy fern genus Hymenophyllum s.l. using the rbcL and rps4 genes and the intergenic spacer rps4-trnS. Because of variation in length of the noncoding marker, we tested and compared three methods for integrating indels. They proved to be useful for estimating a phylogeny of the genus. The rps4-trnS marker, with coded indels integrated, produced better resolution than analysis of either rps4 or rbcL, and combining the three data sets allowed us to obtain a well resolved and strongly supported topology. We interpret our data as showing support for the classical bigeneric system for the family, and call into question several classifications proposed in the past century. The segregate genera Cardiomanes, Hymenoglossum, Serpyllopsis, and Rosenstockia are embedded within Hymenophyllum s.l. Although the deepest relationships within the genus remain uncertain, two subgenera described by Morton do have some support: (1) Sphaerocionium, in which the problematic section Microtrichomanes is embedded; and (2) a diverse Hymenophyllum, including species that were placed originally in Serpyllopsis, Rosenstockia, Hemicyatheon, and Craspedophyllum by Copeland. Subgenus Mecodium appears to be polyphyletic; nevertheless, a subgroup within Mecodium is strongly supported. Several unexpected associations gain support from cytological data and certain morphological characters not previously used to distinguish species groups within Hymenophyllum s.l.     

Molecular systematics of the genus Artibeus (Chiroptera: Phyllostomidae)

A molecular phylogeny of the genus Artibeus using 19 of the 20 recognized species, many with samples from a broad geographic range, is presented. The analysis shows a clear distinction between the two subgenera (or genera), the 'large'Artibeus and the 'small'Dermanura, in both mitochondrial and nuclear genes. The placement and status of A. concolor remains inconclusive and is presented as the third subgenus Koopmania. The phylogenies and divergence time estimates show a marked influence of the Andes in the formation of the subgenera and the main lineages inside each subgenus. Nuclear genes showed a highly incomplete lineage sorting among species inside subgenera Artibeus and Dermanura. Indeed, shared alleles were also found between Artibeus and Koopmania, which are presumed to have split apart during the Miocene, showing that great care should be taken in using these markers. Cytochrome-b gene divergences and monophyly analyses suggest that A. lituratus and A. intermedius are indeed conspecifics. These analyses also suggested the existence of at least four 'new' species revealing a significant cryptic diversity inside the genus.