Protein variation and systematics of three subgenera of Malayan rats (Rodentia: Muridae, genus Rattus Fischer).

1. Nine erythrocyte proteins coded by a separate locus each were analysed in and among seven Malayan species of Rattus belonging to three subgenera. 2. Electrophoretic data obtained confirm the specific status of the seven taxa and divide the seven species into three groups which correspond with Ellerman's (1949) subgenera Stenomys, Maxomys and Leopoldamys. 3. A comparative study together with 11 other species of Malayan Rattus previously analysed show that, with few exceptions, the overall relationships among the 18 species based on electrophoretic data correspond well with conclusions based on morphological evidence. 4. Malayan species of Rattus are relatively very diverse genetically (S = 0.27, range 0.01-0.94).     

Enzyme polymorphism in Malayan rats of the Subgenus Rattus

Electrophoretic variation in nine red cell proteins was analysed in 256 specimens belonging to six species of Malayan Rattus (including one with two subspecies) of the subgenus Rattus. The average proportion of loci heterozygous per individual for the taxa analysed is 0.04. With the exception of Rattus rattus diardii, R. tiomanicus tiomanicus and R. t. jalorensis, individuals of the other species could be identified by specific electrophoretic phenotypes of one or more of the markers analysed. Relationships among the species studied were elucidated by the classical and phenetic approaches employing electrophoretic characters. The results obtained by the two approaches were similar in most respects and they corresponded better with results based on morphological characters than those based on cytological characters.     

六种鼠乳酸脱氢酶和超氧化物歧化酶位点变异的研究

用电泳比较分析了鼠科动物６个种的组织ＬＤＨ同工酶的Ａ、Ｂ、Ｃ亚基和ＳＯＤ同工酶位点的种属差异。结果表明,ＬＤＨ的Ａ和Ｂ亚基在进化上的可变性程度不同。在被分析的２个属共６种鼠中,首次发现Ｂ亚基的结构具有属的特征,同属的鼠种Ｂ亚基泳动度相同,在垂直凝胶电泳板上处于同一泳动线上。不同属的鼠其Ｂ亚基泳动度不同,家鼠属的鼠Ｂ亚基比姬鼠属的泳动快;Ａ亚基的结构既有属的特性,更具有种的特征,同属不同种的鼠Ａ亚基泳动速度不同,表现为ＬＤＨ同工酶带的间距不同。ＬＤＨ的Ｃ亚基结构因鼠种不同而异,由Ｃ亚基组成的ＬＤＨ－Ｘ带黄毛鼠位于自身的ＬＤＨ－３和ＬＤＨ－４之间,社鼠和褐家鼠此带位于自身的ＬＤＨ－４和ＬＤＨ－５之间,白腹巨鼠此带位于自身的ＬＤＨ－５以外的阴极端,与黑线姬鼠此带的位置特征相同。ＳＯＤ同工酶带只表现种的差异,其３条带泳动速度的改变具有协同而变的共同特点。被分析的鼠种经配对法比较生化特征的相同程度,初步表明黄毛鼠亲缘上与褐家鼠比较近,白腹巨鼠亲缘上又比其余３种鼠更近于姬鼠属。     

Circulation of parasites among fishes from lakes in the Caribou Mountains,Alberta, Canada

Circulation of 24 macroparasite species among 12 species of fish was evaluated within samples of hosts collected from 9 lakes on an isolated plateau in northern Alberta, Canada. Twenty-seven parasite taxa (24 species plus the larval stages of Triaenophorus crassus, T. stizostedionis, and Raphidascaris acus) had the potential to be circulated among hosts. Sixteen parasite taxa were recovered from a single host species within a lake. Of the 11 remaining nonspecialist taxa, 4 were larval stages that matured in fish or birds and 7 were adults. Eight of the 11 cases of circulation among hosts involved lake whitefish, and this host was involved in the transmission of 5 species to piscivorous fishes. Despite evidence for the circulation of 7 taxa among the 4 species of sympatric Salmonidae, 60-99% of all worms were recovered from just 1 species of host. These results indicated that approximately 60% of the parasite taxa that infected fish in these lakes were absolute host specialists. The remaining 40% of parasite taxa had restricted host ranges, with most examples of parasite circulation limited to the 2 species of sympatric coregonid.     

Dentition of eight species of Mediterranean Sea Gobiidae: do dentition characters of gobies reflect phylogenetic relationships?

Oral and pharyngeal dentition was analysed in eight Mediterranean species of five different genera using scanning electron microscopy (SEM). Number, position, shape and size of teeth in the jaws and the pharyngeal tooth plates were used as a basis for comparison among taxa. Three different groups could be established based on the dental morphology among the species investigated and homoplasy due to feeding ecology cannot be considered the reason for similarity among them. The established groups are suggested to reflect phylogenetic relationships and correspond with the scarce published data on the topic.     

How many species of Apodemus and Rattus occur in China? A survey based on mitochondrial cyt b and morphological analyses

Apodemus(mice) and Rattus(rats) are the top rodent reservoirs for zoonoses in China, yet little is known about their diversity. We reexamined the alpha diversity of these two genera based on a new collection of specimens from China and their cyt b sequences in Gen Bank. We also tested whether species could be identified using external and craniodental measurements exclusively. Measurements from 147 specimens of Apodemus and 233 specimens of Rattus were used for morphological comparisons. We analysed 74 cyt b sequences of Apodemus and 100 cyt b sequences of Rattus to facilitate phylogenetic estimations. Results demonstrated that nine species of Apodemus and seven species of Rattus, plus a new subspecies of Rattus nitidus, are distributed in China. Principal component analysis using external and craniodental measurements revealed that measurements alone could not separate the recognized species. The occurrence of Rattus pyctoris in China remains uncertain.     

Temporal and Taxonomic Variability in Response of Fauna to Riparian Restoration

Evaluating the success of restoration projects requires well‐designed studies. Among the decisions that need to be made are what taxonomic groups to study and when to conduct the monitoring. To explore how these decisions can influence assessments of restoration success, we examined species richness and composition data collected over several years on different terrestrial fauna (landbirds, rodents, bees, and beetles) at Sacramento River restoration and remnant riparian sites. Our selection of study organisms enabled us to ask whether variability in species richness among restoration sites is less for vagile taxa than for sedentary taxa, and if invertebrates display greater variability among sites than vertebrates. Our results demonstrate that responses to restoration can vary depending upon the season when it is assessed, and the taxa that are studied. For all taxa except bees, there was considerable variability in the relative performance of taxa at restoration sites from one sampling date to the next, such that the relative ranking of the sites often changed dramatically. Comparisons of β ‐diversity (variability in species richness across sites) revealed that certain taxonomic groups were more spatially variable in their response to restoration than others. Among vertebrates, sedentary taxa (rodents) had significantly higher variability in species richness across sites than highly vagile taxa (birds); however, no such pattern was observed for invertebrates. Overall, vertebrates had lower variability than invertebrates, suggesting that evaluations of restoration success based on a few better‐known taxonomic groups (e.g., birds, rodents) may be inadequate to represent the biodiversity response of other groups (e.g., insects).     

Comparative patterns of postcranial ontogeny in therian mammals: an analysis of relative timing of ossification events

Data on the relative sequence of ossification of postcranial elements for eight therian mammals (Myotis lucifugus, Homo sapiens, Rattus norvegicus, Mus musculus, Mesocricetus auratus, Cavia porcellus, Didelphis albiventris, and Sminthopsis macroura) and three outgroups (Chelydra serpentina, Alligator mississippiensis, and Lacerta vivipara) were taken from the literature. For each species, a matrix was constructed in which the relative timing of the onset of ossification in 24 elements was summarized. This resulted in 276 event pairs (characters) for each species. Thirty-three (33.3)% of the characters examined are uniform across all taxa, 16.3% are variable but uninformative in the phylogeny, and 50.4% potentially deliver diagnostic features for clades of two or more taxa. In all species examined, the clavicle is the first bone to appear. Placentalia is not unequivocally diagnosed by the state of any event pair, while Marsupialia has the largest amount of autapomorphies with 18. The acceleration in the timing of ossification of the scapula in relation to the hindlimb in marsupials is most probably causally correlated to movements after birth and during early phases of pre-weaning life. Marsupials are almost unique among amniotes in that the earliest onset of ossification of at least one element among carpals and among tarsals is simultaneous. Three parsimony analyses, each one with a different reptilian taxon as outgroup, were performed using event pairs as characters. In all cases, results were incongruent with the phylogeny of the studied taxa.     

Variation of Nuclear DNA Content in the Biflorus Species of Lonchocarpus (Leguminosae)

This represents the first study of nuclear DNA content in alarge sample (135 spp.) from a tropical arboreal genus, in whicha large proportion of the species were examined (42 spp., 31.1%).Somatic chromosome numbers and 4C-DNA values for 51 taxa ofLonchocarpus are reported. All taxa were diploid with 2 n =22,but their DNA content ranged from 1.92 to 2.86 pg 4C nucleus,corresponding to a 48.95% variation in genome size. In the 74collections studied, no correlation was observed between DNAcontent and habitat altitude. Variation in nuclear DNA contentwas analysed at the level of genus, subgenus, section and subsection.Variation in genome size was also studied within some species,either among widely separated populations or among differentintraspecific taxa. Very little variation in genome size wasdetected between populations, subspecies, and varieties of thesame species. The taxonomic implications of variation in nuclearDNA content are discussed.Copyright 2000 Annals of Botany Company Lonchocarpus (Leguminosae), DNA content, chromosome number.     

Molecular phylogeny of the Praomys complex (Rodentia: Murinae): a study based on DNA/DNA hybridization experiments.

Within the Murinae (Muridae: Rodentia), the African rats of the Praomys group, whose systematics has been studied through different approaches, have raised numerous taxonomic problems. Different taxa related to Praomys have successively been described, among which Mastomys, Myomys and Hylomyscus were considered either as separate genera or subgenera of Praomys. In order to clarify the relationships within the Praomys group, we conducted a series of DNA/DNA hybridization experiments involving different species of Praomys, Mastomys, Myomys and Hylomyscus plus other Murinae and a Cricetomyinae. This study indicates that the Praomys complex is a monophyletic entity clearly separated from the other African and Asian Murinae. If Mastomys and Hylomyscus appeared to be independent genera, the taxonomic situation of Praomys and Myomys is more difficult to ascertain. Indeed, Praomys tullbergi appears more closely related to Myomys daltoni than to another species of Praomys , namely P. jacksoni , suggesting paraphyly for Praomys. Furthermore, P. jacksoni is as distant from P. tullbergi as from any species of Mastomys. Additional species of Praomys and, especially, of Myomys , are needed for reaching a definitive conclusion on these latter taxa. The Praomys group is more related to Mus than to Rattus. To calibrate our molecular distances with geological time, we used a dating of 10 Myr for the Musi Rattus dichotomy. The inferred rate of molecular evolution suggests a dating of c. 8 Myr for the separation of the Praomys group from the Mus lineage.     

Testing morphology-based hypotheses of phylogenetic relationships in Parmeliaceae (Ascomycota) using three ribosomal markers and the nuclear RPB1 gene

Parmeliaceae is the largest family of lichen-forming fungi with more than 2000 species and includes taxa with different growth forms. Morphology was widely employed to distinguish groups within this large, cosmopolitan family. In this study we test these morphology-based groupings using DNA sequence data from three nuclear and one mitochondrial marker from 120 taxa that include 59 genera and represent the morphological and chemical diversity in this lineage. Parmeliaceae is strongly supported as monophyletic and six well-supported main clades can be distinguished within the family. The relationships among them remain unresolved. The clades largely agree with the morphology-based groupings and only the placement of four of the genera studied is rejected by molecular data, while four other genera belong to clades previously unrecognised. The classification of these previously misplaced genera, however, has already been questioned by some authors based on morphological evidence. These results support morphological characters as important for the identification of monophyletic clades within Parmeliaceae.     

Extreme levels of hidden diversity in microscopic animals (Rotifera) revealed by DNA taxonomy

Knowledge and estimates of species richness at all scales are biased both by our understanding of the evolutionary processes shaping diversity and by the methods used to delineate the basic units of diversity. DNA taxonomy shows that diversity may be underestimated by traditional taxonomy, especially for microscopic animals. The effects of such hidden diversity are usually overlooked in ecological studies. Here, we estimate hidden diversity in bdelloid rotifers, a group of microscopic animals. We analyse cryptic diversity using a coalescent approach to infer taxonomical units from phylogenetic trees. Cryptic diversity was measured for eight traditional species of bdelloid rotifers and the results compared to that of the monogonont rotifer Brachionus plicatilis species complex, which is well studied and for which cross-mating experiments have been performed to explicitly define some of the species boundaries. A taxonomic inflation of up to 34 potential cryptic taxa was found in bdelloids. Cryptic taxa within each traditional species may be spatially isolated, but do not have narrower ecological niches. The species deemed as generalists exhibit the highest cryptic diversity. Cryptic diversity based on molecular characterization is commonly found in animals; nevertheless, the amount of cryptic diversity in bdelloids is much higher than in other groups analysed so far, maybe because of their peculiar parthenogenetic reproduction, other than microscopic size. We discuss this hypothesis in the light of the available empirical evidence from other groups of microscopic invertebrates, such as tardigrades and mites, which share size, habitat heterogeneity, potential for dispersal, and/or parthenogenetic reproduction.     

Phylogenetic analysis of southern hemisphere flat oysters based on partial mitochondrial 16S rDNA gene sequences

Oysters are among the most familiar, best studied, and morphologically variable of all marine invertebrate taxa. However, our knowledge of oyster phylogeny and systematics is rudimentary, especially for the subfamily Ostreinae (flat oysters). It is unclear, for instance, whether the predominant flat oysters occurring between latitudes 35 and 50 degrees S constitute a single circumglobal species, or multiple, phylogenetically distinct, regional taxa. We have performed the first DNA molecular phylogenetic analysis of ostreinid taxa to distinguish among competing phylogenetic and systematic hypotheses for Southern Hemisphere Ostreinae. An approximately 450-nucleotide fragment of the mitochondrial large ribosomal subunit (16S) was sequenced for 41 individual oysters, representing 14 taxa of brooding oysters: 5 Southern Hemisphere Ostreinae, 5 Northern Hemisphere Ostreinae, and 4 outgroup species of the subfamily Lophinae. Phylogenetic analyses of the resulting data set yielded consensus tree topologies that are comprehensively incongruent with prevailing morphologically based interpretations of systematic relationships among the Ostreinae. Three ostreinid mitochondrial clades were evident, each containing representatives of Southern Hemisphere regional ostreinid taxa, some of which robustly cocluster with Northern Hemisphere taxa. These three clades represent the first well-supported phylogenetic framework for this ecologically prominent and commercially important oyster subfamily.     

Structural alignment of 18S and 28S rDNA sequences provides insights into phylogeny of Phytophaga (Coleoptera: Curculionoidea and Chrysomeloidea)

We performed a comparative study of partial rDNA sequences from a variety of Coleoptera taxa to construct an annotated alignment based on secondary structure information, which in turn, provides improved rRNA structure models useful for phylogenetic reconstruction. Subsequent phylogenetic analysis was performed to test monophyly and interfamilial relationships of the megadiverse plant feeding beetle group known as ‘Phytophaga’ (Curculionoidea and Chrysomeloidea), as well as to discover their closest relatives among the Cucujiformia. Parsimony and Bayesian analyses were performed based on the structural alignment of segments of 18S rRNA (variable regions V4‐V5, V7‐V9) and 28S rRNA (expansion segment D2). A total of 104 terminal taxa of Coleoptera were included: 96 species of Cucujiformia beetles, representing the families and most ‘subfamilies’ of weevils and chrysomeloids (Phytophaga), as well as several families of Cleroidea, Tenebrionoidea and Cucujoidea, and eight outgroups from three other polyphagan series: Scarabaeiformia, Elateriformia and Bostrichiformia. The results from the different methods of analysis agree — recovering the monophyly of the ‘Phytophaga’, including Curculionoidea and Chrysomeloidea as sister groups. The curculionoid and chrysomeloid phylogeny recovered from the aligned 18S and 28S rDNA segments, which is independent of morphological data, is in agreement with recent hypotheses or concepts based on morphological evidence, particularly with respect to familial relationships. Our results provide clues about the evolutionary origin of the phytophagan beetles within the megaclade Cucujiformia, suggesting that the sister group of ‘Curculionoidea + Chrysomeloidea’ is a clade of the ‘Cucujoidea’, represented in this study by species in Boganiidae, Erotylidae, Nitidulidae, Cucujidae and Silvanidae. The Coccinellidae and Endomychidae are not grouped with the latter, and the remaining terminal taxa are nested in Tenebrionoidea and Cleroidea. We propose that the combination of structurally aligned ribosomal RNA gene regions 18S (V4‐V5, V7‐V9) and 28S (D2) are useful in testing monophyly and resolving relationships among beetle superfamilies and families.     

Co-variation and indicators of species diversity: Can richness of forest-dwelling species be predicted in northern boreal forests?

Design and establishment of ecologically good networks of conservation areas often requires quick assessments of their biodiversity. Reliable indicators would be useful when doing such assessments. In order to explore the potential indicators for species richness in boreal forests, we studied (1) the co-variation of species richness and composition of species assemblages among beetles, polypores, birds and vascular plants, (2) the relationships between species richness and four boreal forest site types, (3) the relationship between species richness and forest physical structure and (4) the suitability of potential indicator groups within the four taxa to predict the species richness generally. The data show that there are probably not a single taxonomic or forest structural characteristic to be used as a general biodiversity indicator or surrogate for all the species. The correlations in species richness among the four taxa studied were low. However, group-specific indicators were obvious: forest site type was a good surrogate for vascular plant richness, and quantity and quality of dead wood predicted the species richness of polypores. The results support the view that different indicators shall be used for different forest types and taxonomic groups. These indicators should facilitate relatively rapid methods to assess biodiversity patterns at the forest stand level.     

Phylogeny of the sea spiders (Arthropoda, Pycnogonida) based on direct optimization of six loci and morphology

Higher‐level phylogenetics of Pycnogonida has been discussed for many decades but scarcely studied from a cladistic perspective. Traditional taxonomic classifications are yet to be tested and affinities among families and genera are not well understood. Pycnogonida includes more than 1300 species described, but no systematic revisions at any level are available. Previous attempts to propose a phylogeny of the sea spiders were limited in characters and taxon sampling, therefore not allowing a robust test of relationships among lineages. Herein, we present the first comprehensive phylogenetic analysis of the Pycnogonida based on a total evidence approach and Direct Optimization. Sixty‐three pycnogonid species representing all families including fossil taxa were included. For most of the extant taxa more than 6 kb of nuclear and mitochondrial DNA and 78 morphological characters were scored. The most parsimonious hypotheses obtained in equally weighted total evidence analyses show the two most diverse families Ammotheidae and Callipallenidae to be non‐monophyletic. Austrodecidae + Colossendeidae + Pycnogonidae are in the basal most clade, these are morphologically diverse groups of species mostly found in cold waters. The raising of the family Pallenopsidae is supported, while Eurycyde and Ascorhynchus are definitely separated from Ammotheidae. The four fossil taxa are grouped within living Pycnogonida, instead of being an early derived clade. This phylogeny represents a solid framework to work towards the understanding of pycnogonid systematics, providing a data set and a testable hypothesis that indicate those clades that need severe testing, especially some of the deep nodes of the pycnogonid tree and the relationships of ammotheid and callipallenid forms. The inclusion of more rare taxa and additional sources of evidence are necessary for a phylogenetic classification of the Pycnogonida. © The Willi Hennig Society 2006.     

Molecular genetics and speciation in Elliptio and its relationships to other taxa of North American Unionidae (Bivalvia)

The genetic relationships among 30 populations of 11 species and five genera of North American Unionidae were assessed by using standard allozyme procedures. Emphasis was on relationships among populations and species of Elliptio and Fusconaia. Multi-dimensional scaling based on a matrix of Nei's (1972) genetic distances substantiated the immunoelectrophoretic results of Davis&Fuller 1981, which demonstrated the distinct and divergent taxonomic groups Anodontinae, Margaritiferinae, and Ambleminae, plus die close relationship of Elliptio and Fusconaia , which justifies their inclusion within the same tribe. Genetic distance appears to increase regularly with time since divergence of taxa. The E. complanata species group is an apparently recent radiation and probably is actively radiating today. The I values among species of this group range from 0.90 to 0.99. Considerable heterozygosity, numerous polymorphic loci, and much interpopuladon phenotypic diversity was also recorded for this group. Some taxa mat have been considered synonyms are demonstrated to be valid species. Reasons for the low genetic distances among unionid taxa are discussed. Standard allozyme analyses are shown to be of great value for assessing relationships among unionid taxa.     

十大功劳属植物种子形态研究

利用光镜(LM)和扫描电镜(SEM)对十大功劳属24种植物的种子形态进行观察。结果发现十大功劳属植物种子颜色为黑色,长3.4～6.7mm,宽1.7～3.5mm,属大型种子,形状多样;外种皮纹饰为网纹状,网眼形状、大小及网脊粗细、凸凹在不同类群间不完全相同,种内变异稳定,据此可将十大功劳属植物种皮纹饰划分为9种类型。研究结果表明:种子形态在十大功劳属内具有重要的系统学意义,但不支持Ahrendt将十大功劳属下分为2个groups,4个sections,14个subsections的观点。     

Molecular phylogeny of Anthyllis spp

For the genus Anthyllis (Fam. Fabaceae, tribe Loteae), with few exceptions, little information is available on the genetic variation among and within species. This genus contains 20 species distributed throughout Europe, Africa, and the Mediterranean basin. The most widespread species is A. vulneraria, and over 30 intraspecies taxa have been identified based on plant morphology. To study the molecular phylogeny of the genus, the sequences of the internal transcribed spacers ITS1 and ITS2 of the nuclear ribosomal DNA of 10 Anthyllis species, including 11 subspecies of A. vulneraria and three subspecies of A. montana, were obtained and analysed together with sequences of five other species of the genus obtained from GenBank. Our results suggest that the genus Anthyllis is not monophyletic and is divided in two main clades: the Anthyllis sensu strictu and the "tetraphylla clade". The former includes most of the Anthyllis species, and the latter includes three annual species more closely related to Lotus. All the taxa were also analysed according to seven chloroplast microsatellites, and these data closely confirm the results obtained with the ITS phylogeny.     

Parasite survey of a Daphnia hybrid complex: host-specificity and environment determine infection

1. Hybridization between species is a common phenomenon in plants and animals. If parasite prevalence differs for hybrids and parental species (i.e. taxa) there may be considerable consequences for relative hybrid fitness. Some studies have investigated hybrid complexes for infection, and complex-specific differences in parasite prevalence have been detected. 2. Based on the results of a field study on a hybridizing Daphnia population from a single lake, it has been hypothesized that permanently over- or under-infected hybrids do not exist. The observed field-patterns can only be temporal because taxa, in addition to single genotypes, might be the subject of parasite driven host frequency-dependent selection. Thus, parasites will track any common taxon within a hybrid complex. 3. In the present study, hybridizing Daphnia populations from 43 lakes were screened for parasite infections to obtain indirect evidence for coevolutionary cycles. It was hypothesized that, due to time lags between the evolution of resistance in host populations and the evolution of the parasite towards tracking of a common host taxon, the same Daphnia taxon will be over-infected in some lakes, while being under-infected in others. 4. Two of the four parasite species were specialists: their prevalence differed among coexisting Daphnia taxa. The varying infection patterns detected across spatially segregated hybridizing Daphnia populations are consistent with theoretical predictions for coevolutionary cycles. Thus the infection patterns, as observed under natural conditions, are temporal and unstable. 5. Additionally, the spatial distribution of the four parasite species was analysed with respect to habitat differences. The results show that the presence of a particular parasite on a host taxon was determined not only by the host-specificity of the parasite, but also by host-habitat relations.