Polyphyletic Assemblage Research Articles

Molecular phylogeny and biogeography of the land snail genus Monacha (Gastropoda, Hygromiidae)

Monacha is the most species‐rich genus of the family Hygromiidae with a centre of diversity in Anatolia. On the basis of the presence or absence of accessory genital appendages, the group was subdivided into three subgenera, Monacha s. str., Paratheba and Metatheba, in the past. We used mitochondrial and nuclear DNA sequences of a representative sample of species 1) to reconstruct the phylogeny of the major lineages of Monacha, 2) to reconstruct the evolution of the accessory genital appendages, and 3) to reconstruct the biogeography of the group. Our results show that the accessory genital appendages upon which the classification of Monacha into subgenera rested so far, that is the appendicula, which is homologous to the dart sac and/or its accessory sac in other helicoid land snails, and the penis retractor muscle, were lost several times independently in different lineages of Monacha. Even among sister species, these characters were found to be variable. Thus, the typologically defined subgenera are para‐ or polyphyletic assemblages. The reconstruction of the biogeographical history indicated an origin of Monacha in Anatolia and the adjacent Caucasus region which is consistent with the observation that most other genera currently included in the subfamily Monachainae are also endemic to this region. Most major Monacha lineages remained restricted to northern Anatolia. Southern Europe was colonized by Monacha s. str., the Aegean region by Aegaeotheba subgen. n., the Crimean Peninsula by Paratheba and the Levant by Platytheba. On the basis of our phylogenetic analyses and testing of alternative hypotheses, we propose to divide Monacha into eight subgenera. We newly delimit the previously proposed subgenera Monacha s. str., Metatheba, Paratheba and Platytheba, and describe Pontotheba subgen. n., Aegaeotheba subgen. n., Trichotheba subgen. n. and Rhytidotheba subgen. n. as new subgenera.

Revision of the costata-group of Alona s. lato (Cladocera: Anomopoda: Chydoridae) confirms its generic status

By taking Flavalona gen. nov. out of Alona s.l. (Cladocera: Anomopoda: Chydoridae), the last major clade has now been removed from this polyphyletic assemblage. Flavalona gen. nov. is a monophylum defined by having three, rarely two connected head pores and slit-shaped, rarely rounded lateral head pores. Postabdomen rather long, distally narrowed, with robust marginal denticles and weakly developed lateral fascicles of setules. End-claw weakly curved and with short basal spine. Male postabdomen with gonopores opening at the end of a penis-like outgrowth. Trunk limbs: exopodite of P2 with seta; inner portion of P4 with flaming-torch shaped setae; P5 with filter plate of three setae; P6 a large simple lobe. The relationship of the new genus with other Aloninae remains to be determined. A key to the 11 species of the genus is provided and a discussion of their geographic distribution and habitat type is given.

A molecular and morphological reassessment of the phylogeny of the subfamily Ophioninae (Hymenoptera: Ichneumonidae)

The phylogeny of the subfamily Ophioninae (Hymenoptera: Ichneumonidae) is investigated using molecular markers and morphological characters. We analysed the mitochondrial DNA CO1 and the nuclear 28S D2–D3 gene fragments for 74 species of Ophioninae from 25 out of the 32 recognized genera, which collectively represent 98% of described species diversity of the subfamily. Molecular markers were analysed separately and combined, with or without the adjunction of a matrix of 62 morphological characters using Bayesian inference. Our results reveal three distinct lineages, each including one of most speciose genera: Ophion, Enicospilus and Thyreodon. The comparison of the molecular data, and combined molecular plus morphological data led to the definition of the three tribes: Ophionini stat. rev. (Ophion + Alophophion + Rhopalophion + Xylophion + Afrophion); Enicospilini stat. rev. (Enicospilus + Laticoleus + Dicamptus + Hellwigiella); and Thyreodonini tribe nov. (Thyreodon + Dictyonotus + Rhynchophion). The possible association of other genera to one or another of these lineages is discussed. Ophion is a polyphyletic assemblage and requires a further revision to define the delimitation with close genera. The enigmatic Old World genus Skiapus is strongly supported as belonging to the Ophioninae, although its placement within the subfamily is ambiguous as a result of its derived genotype and phenotype. Finally, we propose a biogeographical scenario supported by this phylogeny and based on the limited available fossil data. (Resume d'auteur)

Phylogenetic relationships within Diplotaxini Kirby (Coleoptera: Melolonthidae: Melolonthinae) with emphasis on LiogenysGuérin‐Méneville

AbstractDiplotaxini Kirby is one of the 29 tribes of Melolonthinae with Nearctic, Neotropical, Paleartic, Afrotropical and Oriental distribution. According to the current classification, Diplotaxini is composed of 706 species described in 21 genera. Neotropical Diplotaxini comprise 94 species, of which 78 are members of Liogenys Guérin Méneville, the largest Neotropical genus. Until now, no phylogenetic studies on Diplotaxini have tested whether the tribe is natural or artificial. This study tested the relationships among Diplotaxini genera, created hypotheses for better defining them, and assessed the monophyly of Liogenys. Cladistic analyses using 167 adult morphological characters were performed. The 83 included taxa represent three subfamilies of Melolonthidae, four tribes of Melolonthinae, and most genera of Diplotaxini, with emphasis on Liogenys. The data were analysed using parsimony under equal and implied weights. In both analyses, the traditional concept of Diplotaxini is shown to be a polyphyletic assemblage. Empecta Erichson and Clypeasta Fairmaire are closely related to Melolontha melolontha (Linnaeus) and Pseudoliogenys Moser close to Myloxenoides Martínez (Tanyproctini). Pachrodema Blanchard is identified as the sister group of Liogenys. The monophyly of both Pacuvia Curtis and Homalochilus Blanchard is confirmed and the paraphyly of Diplotaxis Kirby is suggested. The analyses strongly supported the polyphyly of Liogenys. To render this genus monophyletic, we transferred L. ferrugata Mannerheim (related to M. melolontha) to Phyllophaga Harris, and L. micropyga Burmeister to Diplotaxis, forming Diplotaxis micropyga (Burmeister, 1855) comb.n.; and included Homoliogenys tarsalis (Moser) and Hilarianus anguliceps Blanchard in Liogenys. As H. anguliceps is syn. junior of Liogenys punctaticollis, Hilarianus is synonymized with Liogenys. Hilarianus ovalis and Hilarianus rufinus are here assigned to Manonychus, and Hilarianus uniformis and Hilarianus suboblongus to Blepharotoma, forming: Blepharotoma uniformis comb.n., Blepharotoma suboblongus comb.n., Manonychus ovalis comb.n. and Manonychus rufinus comb.n.

Neotypification of the name Crocus biflorus Mill. (Iridaceae) and its consequences in the taxonomy of the genus

Recent phylogenetic investigations on the genus Crocus proved several infra-generic units predominantly within section Nudiscapus to be para- or polyphyletic even at infra-specific level. In particular, the 23 “subspecies” of C. biflorus Mill. turned out to be a polyphyletic assemblage grouping in very different clades and sub-groups. In addition, they were established under the binomial Crocus biflorus, not yet typified. As first step, we neotypified this name. Then, through a phylogeny based on the ETS region of the nuclear ribosomal (nr) DNA as an additional nuclear marker to the already available nrITS region, we further demonstrated that all the “subspecies” represent independent evolutionary lineages. Therefore, all these taxa are treated here at species level. To achieve this, 10 new combinations are proposed.

A Novel Lineage of ‘Naked Filose Amoebae’; Kraken carinae gen. nov. sp. nov. (Cercozoa) with a Remarkable Locomotion by Disassembly of its Cell Body

The term 'filose amoebae' describes a highly polyphyletic assemblage of protists whose phylogenetic placement can be unpredictable based on gross morphology alone. We isolated six filose amoebae from soils of two European countries and describe a new genus and species of naked filose amoebae, Kraken carinae gen. nov. sp. nov. We provide a morphological description based on light microscopy and small subunit rRNA gene sequences (SSU rDNA). In culture, Kraken carinae strains were very slow-moving and preyed on bacteria using a network of filopodia. Phylogenetic analyses of SSU sequences reveal that Kraken are core (filosan) Cercozoa, branching weakly at the base of the cercomonad radiation, most closely related to Paracercomonas, Metabolomonas, and Brevimastigomonas. Some Kraken sequences are >99% similar to an environmental sequence obtained from a freshwater lake in Antarctica, indicating that Kraken is not exclusively soil dwelling, but also inhabits freshwater habitats.

Typification of the Linnaean name Centaurea sibirica (Asteraceae)

Centaurea Linnaeus (1753: 909) (Asteraceae) comprises a large number of taxa mainly occurring in the Mediterranean region and southwest Asia (Susanna & Garcia-Jacas 2007). The former wide concept of Centaurea resulted in a polyphyletic assemblage, and it has been recently split into several putatively monophyletic genera Centaurea, Psephellus Cass. and Rhaponticoides Vaill. (Wagenitz & Hellwig 2000; Greuter 2003; Hellwig 2004; Susanna & Garcia-Jacas 2007, 2009). Centaurea sibirica Linnaeus (1753: 913) is spreading from S Russia to W Siberia and Central Asia (Wagenitz & Hellwig 2000), it is one of the species of sixty-nine names in Centaurea described by Linnaeus and is currently accepted as Psephellus sibiricus (L.) Wagenitz (Wagenitz & Hellwig 2000: 37). However, from a nomenclatural standpoint, Centaurea sibirica has not been typified (Jarvis 2007, Ferrer-Gallego et al. 2014a, 2014b, 2014c, Altınordu & Ferrer-Gallego 2015, Ferrer-Gallego & Altınordu 2016, Iamonico & Peruzzi 2016). This paper designates a lectotype for C. sibirica based on the protologue and consultation of Linnaeus’s original material.

Current and future perspectives on the systematics, taxonomy and nomenclature of testate amoebae

Testate amoebae are a polyphyletic assemblage of at least three major, unrelated taxonomic groups of unicellular amoeboid eukaryotes exhibiting a test. The focus on testate amoebae in scientific research has greatly increased in the past 20 years: from an average of about 5 papers a year in the mid-1990s to the current rate of more than 50 papers published yearly. The application range of these organisms is rapidly expanding as well: from the traditional fields of environmental monitoring and paleoecology, to forensic sciences and ecotoxicology studies. These developments are nevertheless strongly dependent on reliable taxonomy and nomenclature. However, scientometric data reveal that despite an ever-increasing necessity for the use of names (the product of taxonomy), the corresponding effort has not been achieved for improving testate amoebae systematics. As a consequence, inaccurate taxonomy yields to misinterpretations in the diversity of the organisms and to potentially incorrect conclusions. These and related problems are discussed in this study, highlighting the outcome of poor taxonomic expertise in accurate classification and phylogeny of testate amoebae, and the consequences derived from it. Additionally, this study is aimed to discuss the current status of testate amoebae classification, and to present all nomenclature and taxonomic changes in higher and lower taxonomic levels of testate amoebae, as a result of recent molecular reconstructions. Finally, we conclude with a list of the needs and suggestions toward a unified and modernized taxonomy of testate amoebae.

Towards a sound definition of Skeneidae (Mollusca, Vetigastropoda): 3D interactive anatomy of the type species, Skenea serpuloides (Montagu, 1808) and comments on related taxa

The family Skeneidae, originally characterized by their minute size, lack of nacre and a rhipidoglossate radula, is an example of a polyphyletic assemblage. Most ‘skeneimorph’ species are based on the shell, sometimes the radula and rarely features of the external body. Data on internal anatomy are almost entirely lacking. In order to provide a complete anatomical data set with histological information, we applied serial semithin sectioning and 3D reconstructions to describe and visualize the anatomy of the type species of Skeneidae, Skenea serpuloides (Montagu, 1808). In addition, comparative data are provided for three other Skeneidae, Skenea profunda Friele, 1879; Dillwynella lignicola Marshall, 1988 and Dillwynella voightae Kunze, 2011 as well as for a tiny turbinid-like species, Lodderena minima (Tenison-Woods, 1887). We diagnose Skeneidae as trochoidean vetigastropods with combined epipodial sense organs (ESOs), neck lobes, eyes with a closed vesicle and the diagnostic propodial penis. Other features include simultaneous hermaphroditism with distinct testis/vas deferens and ovary/oviduct, a urogenital opening with the right kidney and a distinct seminal receptacle. Several features of Skeneidae are explained by dwarfing through progenesis, and accordingly, we interpret paedomorphosis of various characters. In contrast, L. minima has a true hermaphroditic gland, but lacks of propodial penis and a receptaculum. Also, molecular data support an exclusion of Lodderena from the Skeneidae.

Hesperus rougemonti sp. n. (Coleoptera, Staphylinidae) from Borneo.

The genus Hesperus Fauvel is, in its current concept, an obviously polyphyletic assemblage. One of the species groups that stand out, due to a combination of characters unusual for Hesperus, is the borneensis group. These characters are the subserrate antennae and the paramere bearing numerous peg setae. Otherwise, the members of this group look as typical for a Hesperus as it can be. At present, the group comprises the following species: H. birmanus Cameron, 1932, H. borneensis Bernhauer, 1915, H. javanus Cameron, 1937, H. malayanus Cameron, 1932a, H. susannekontrusae Schillhammer, 2005, H. temburong Schillhammer, 2002, H. watanabei Shibata, 2002, and H. wemmeri Schillhammer, 2002.

DNA barcoding reveals twelve lineages with properties of phylogenetic and biological species within Melitaea didyma sensu lato (Lepidoptera, Nymphalidae).

The complex of butterfly taxa close to Melitaea didyma includes the traditionally recognized species Melitaea didyma, Melitaea didymoides and Melitaea sutschana, the taxa that were recognized as species only relatively recently (Melitaea latonigena, Melitaea interrupta, Melitaea chitralensis and Melitaea mixta) as well as numerous described subspecies and forms with unclear taxonomic status. Here analysis of mitochondrial DNA barcodes is used to demonstrate that this complex is monophyletic group consisting of at least 12 major haplogroups strongly differentiated with respect to the gene COI. Six of these haplogroups are shown to correspond to six of the above-mentioned species (Melitaea didymoides, Melitaea sutschana, Melitaea latonigena, Melitaea interrupta, Melitaea chitralensis and Melitaea mixta). It is hypothesized that each of the remaining six haplogroups also represents a distinct species (Melitaea mauretanica, Melitaea occidentalis, Melitaea didyma, Melitaea neera, Melitaea liliputana and Melitaea turkestanica), since merging these haplogroups would result in a polyphyletic assemblage and the genetic distances between them are comparable with those found between the other six previously recognized species.

Molecular phylogeny reveals the polyphyly of the snail genus Cepaea (Gastropoda: Helicidae)

Snails in the genus Cepaea are important model organisms in ecogenetic studies because of their colour and banding polymorphism. The monophyly of this group has been almost unanimously assumed based on superficial similarities in shell form and colouration. However, molecular phylogenetic analyses based on mitochondrial and nuclear sequences of 20 genera of Helicidae unequivocally demonstrated that Cepaea as currently understood is a polyphyletic assemblage. Only C. nemoralis and C. hortensis are retained in Cepaea, whereas C. vindobonensis is referred to Caucasotachea and C. sylvatica to Macularia based on our molecular phylogeny. Cepaea and Macularia belong to the western clade of the Helicinae, whereas Caucasotachea is nested in the eastern clade which probably diverged in the late Eocene. Because of the large phylogenetic distances between Cepaea, Macularia and Caucasotachea, it has to be shown whether the genetic mechanism underlying the simpler banding polymorphism in C. vindobonensis and M. sylvatica is a simpler version of the supergene that determines the polymorphism in Cepaea in the strict sense. This case illustrates the importance of sound phylogenetic analyses as a basis for any predictions in comparative biology.

Not all jellyfish are equal: isotopic evidence for inter- and intraspecific variation in jellyfish trophic ecology.

Jellyfish are highly topical within studies of pelagic food-webs and there is a growing realisation that their role is more complex than once thought. Efforts being made to include jellyfish within fisheries and ecosystem models are an important step forward, but our present understanding of their underlying trophic ecology can lead to their oversimplification in these models. Gelatinous zooplankton represent a polyphyletic assemblage spanning >2,000 species that inhabit coastal seas to the deep-ocean and employ a wide variety of foraging strategies. Despite this diversity, many contemporary modelling approaches include jellyfish as a single functional group feeding at one or two trophic levels at most. Recent reviews have drawn attention to this issue and highlighted the need for improved communication between biologists and theoreticians if this problem is to be overcome. We used stable isotopes to investigate the trophic ecology of three co-occurring scyphozoan jellyfish species (Aurelia aurita, Cyanea lamarckii and C. capillata) within a temperate, coastal food-web in the NE Atlantic. Using information on individual size, time of year and δ13C and δ15N stable isotope values, we examined: (1) whether all jellyfish could be considered as a single functional group, or showed distinct inter-specific differences in trophic ecology; (2) Were size-based shifts in trophic position, found previously in A. aurita, a common trait across species?; (3) When considered collectively, did the trophic position of three sympatric species remain constant over time? Differences in δ15N (trophic position) were evident between all three species, with size-based and temporal shifts in δ15N apparent in A. aurita and C. capillata. The isotopic niche width for all species combined increased throughout the season, reflecting temporal shifts in trophic position and seasonal succession in these gelatinous species. Taken together, these findings support previous assertions that jellyfish require more robust inclusion in marine fisheries or ecosystem models.

Molecular phylogenetics of sculpins of the subfamily Oligocottinae (Cottidae)

The sculpin subfamily Oligocottinae includes 18–20 species of nearshore benthic fishes with a diverse array of reproductive strategies. As a first step toward understanding the evolution of that diversity, we conducted a phylogenetic study based on DNA sequences from eight genomic regions from 31 sculpin species aimed at testing monophyly and relationships of the Oligocottinae. Representatives from the perciform families Agonidae, Cottidae, Hemitripteridae, Hexagrammidae, Psychrolutidae, and Rhamphocottidae served as outgroups. The sequence data were analyzed in maximum likelihood and Bayesian phylogenetic inference frameworks. Results of these analyses show that a systematic revision of the group is warranted. The genus Clinocottus is a polyphyletic assemblage of three distinct lineages, which should be indicated by resurrection of the subgenera Blennicottus, Clinocottus, and Oxycottus; Leiocottus hirundo is more closely related to Clinocottus analis than C. analis is related to any other member of Clinocottus; the composition of the tribe Oligocottini should be revised to include only the genera Oligocottus, Clinocottus, and Orthonopias; and the genus Sigmistes should be removed from the subfamily Oligocottinae.

Genital morphology and mating behaviour of Allostethus (Dermaptera), an earwig genus of enigmatic phylogenetic position

In the suborder Forficulina (order Dermaptera; earwigs), the families Apachyidae, Anisolabididae, and Labiduridae form a possibly paraphyletic assemblage Mesodermaptera, which is characterized by laterally paired penes that point in opposite directions (anterior and posterior) when in repose. A previous study of a labidurid species, Labidura riparia (Pallas, 1773), revealed that males predominantly use the right penis for insemination, although both penes are functional. This result suggests that labidurids may have retained handedness in penis use, leading eventually to the loss of the less frequently used left penis in the common ancestor of the Eudermaptera, estimated to be the sister clade of Labiduridae. However, Haas & Kukalovà-Peck (2001: European Journal of Entomology 98: 445 – 509) included another representative of Labiduridae, Allostethus indicum (Burmeister, 1838) (Allostethinae) in their extensive phylogenetic analysis, and found that hindwing structures of this species showed multiple plesiomorphic characteristics, making Labiduridae (sensu lato) a polyphyletic assemblage. The aim of the present study was to describe the genital structures and copulation of A. indicum in detail. The genital morphologies of a congener and other labidurid genera (Nala, Labidura, Forcipula) were also examined for comparison. Male A. indicum predominantly used (or were ready to use) the right penis for insemination, as in L. riparia. However, the possible female genital structure responsible for this handedness differed between the two species: the base of the spermatheca showed a striking spiral in L. riparia, while the spermatheca opened to an asymmetrically arranged vagina in Allostethus. Female Allostethus also possessed a pair of elongated thin tubes, which have to date been reported only for the basal groups of earwigs, as well as the vagina and the internally branched spermatheca. The developmental origin of an ovipositor-like sutucture also differs between Allostethus and the other labidurids examined, lending support to the polyphyly of Labiduridae sensu lato.

TAXONOMY OF POLYPORUS SENSU LATO AND RELATED GENERA (BASIDIOMYCOTA) FROM SANTA MARIA, SOUTHERN BRAZIL

Polyporus has traditionally been treated at a generic status, but currently, it is considered as a polyphyletic assemblage of some poroid stipitate genera and morphological groups of fungi to be better understood. Ten species of Polyporus sensu lato and one species of Echinochaete (Polyporales, Basidiomycota) were identified to the region of Santa Maria, Rio Grande do Sul State, southern Brazil. Fresh basidiomes were collected and analyzed in order to present their illustrated morphological redescriptions. Polyporus subpurpurascens is recorded for the first time from Brazil.

Molecular evidence for the polyphyletic origin of low pH adaptation in the genus Klebsormidium (Klebsormidiophyceae, Streptophyta)

Background and aims – Algae living in low pH environments have been the subject of numerous studies, but their phylogenetic relationships with relatives found in non-acidic habitats are poorly known. In the present study we analyzed the morphology and phylogeny of acid-adapted strains of Klebsormidium, a genus of filamentous green algae frequently present in low pH environments. Methods – Eighteen strains of Klebsormidium were collected from from low pH habitats in Europe and U.S.A., mainly from terrestrial sites affected directly or indirectly by carbon mining activities. These algae were isolated in culture and their phylogenetic relationships were studied using rbcL and ITS rDNA sequence data in a concatenated dataset. Key results – In the molecular phylogeny the strains of Klebsormidium living in low pH habitats formed a polyphyletic assemblage. They were representative of sixteen lineages and corresponded morphologically to six species (K. crenulatum, K. elegans, K. flaccidum, K. fluitans, K. nitens, K. scopulinum), with the exception of four strains for which an unambiguous identification was not possible. Conclusions – The genus Klebsormidium is a group of morphologically and physiologically dynamic algae in which the capacity of adaptation to low pH conditions has been developed multiple times independently. Extreme acidophilic populations probably originate from populations of various species growing locally when strongly acidic habitats become available. For the acid-adapted lineages of Klebsormidium examined here the current known distribution is geographically restricted, with the exception of a lineage containing strains from Czech Republic, New Zealand and Ohio.

Studies on woloszynskioid dinoflagellates VII. Description of Borghiella andersenii sp. nov.: light and electron microscopy and phylogeny based on LSU rDNA

Freshwater woloszynskioid dinoflagellates were collected independently in Scotland and Portugal and found to belong to a previously unknown species of the genus Borghiella, here described as B. andersenii. The new species differs in morphology and nuclear-encoded LSU rDNA and ITS sequences from B. dodgei and B. tenuissima, the two species presently comprising the genus Borghiella. Unusual features of the new species were observed particularly during asexual reproduction, which took place in the motile stage – as in many other dinoflagellates – or in a so-called division cyst, recalling cell division in the family Tovelliaceae. Such diversity in cell division is rarely reported in dinoflagellates. Morphologically Borghiella andersenii differs from B. tenuissima in being only slightly compressed dorsoventrally whereas the latter species is flat. The slight compression is also visible in lateral view. Borghiella andersenii and B. dodgei are more challenging to discriminate but the apical structure complex is only half the length in B. andersenii compared with B. dodgei (3–4 vs 6 µm). This difference can only be accounted for in the scanning electron microscope. At the light microscopy level the epicone in B. andersenii is rounded whereas it is conical in B. dodgei. Sexual reproduction in Borghiella andersenii was homothallic by formation of planozygotes, followed by apparent resting cysts. Phylogenetic studies on woloszynskioids have recently shown that they comprise a polyphyletic assemblage, which has been divided into the three families Borghiellaceae, Tovelliaceae and Suessiaceae. New species of the three families are now being found rapidly in many parts of the world, proving that the techniques required to investigate these small, morphologically similar dinoflagellates are now in place and proving that such ‘gymnodinioids’ or ‘woloszynskioids’ comprise an often overlooked biological entity in both marine and freshwater biotopes. Based on LSU rDNA, B. andersenii is most closely related to B. tenuissima.

Environmental upheavals of the Ediacaran period and the Cambrian “explosion” of animal life

The second half of the Ediacaran period began with a large impact – the Acraman impact in South Australia, which was accompanied by a negative δ13Ccarb anomaly and an extinction-radiation event involving acritarchs. A few million years later (∼570 Ma?) there was a second, deeper and longer-lived world-wide δ13Ccarb anomaly (the Shuram anomaly) which coincides with extinction of the acanthomorphic acritarchs. Wide distribution of the Shuram event is exemplified by stratigraphic sections from South Australia, Oman, southern California and South China. The widespread anomaly has been tentatively attributed to a marine impact. During recovery from the Shuram event the enigmatic Ediacaran biota achieved its zenith, only to be extirpated and replaced by a polyphyletic assemblage of shelly animals in what is known as the Cambrian “explosion”. This extinction-radiation cycle was preceded by glaciation, another δ13Ccarb excursion and the highest 87Sr/86Sr values known from marine carbonates. These high Sr ratios have been linked to weathering of extensive tracts of continental crust that were elevated during amalgamation of the supercontinent Gondwana. Introduction of essential nutrients to the oceans would have promoted biological production of oxygen and provided P and Ca for the important skeletonization that characterizes the Cambrian “explosion” and caused a quantum leap in the preservation potential of animal remains. Turbulent events of the last 50 million years of Precambrian time include three glaciations, two large impacts and a massive orogenic episode. These dramatic environmental upheavals are held responsible for three consecutive extinction-radiation cycles that culminated in the appearance of a diverse array of shelly fossils. Various lines of evidence suggest that the metazoans have deep roots so that they too may have been subjected to the environmental pressures of the late Ediacaran period clearly illustrated by acritarchs and the Ediacaran biota but the long-lived diversity of the metazoan population was “suddenly” revealed by the acquisition of biomineralization.

Molecular characterization and phylogenetics of Fennoscandian cowpox virus isolates based on the p4c and atip genes.

BackgroundCowpox virus (CPXV), a rodent-borne Orthopoxvirus (OPV) that is indigenous to Eurasia can infect humans, cattle, felidae and other animals. Molecular characterization of CPXVs isolated from different geographic locations is important for the understanding of their biology, geographic distribution, classification and evolution. Our aim was to characterize CPXVs isolated from Fennoscandia on the basis of A-type inclusion (ATI) phenotype, restriction fragment length polymorphism (RFLP) profiles of atip gene fragment amplicon, and phylogenetic tree topology in conjunction with the patristic and genetic distances based on full length DNA sequence of the atip and p4c genes.MethodsATI phenotypes were determined by transmission electron microcopy and RFLP profiles were obtained by restriction enzyme digestion of the atip gene fragment PCR product. A 6.2 kbp region spanning the entire atip and p4c genes of Fennoscandian CPXV isolates was amplified and sequenced. The phylogenetic affinity of Fennoscandian CPXV isolates to OPVs isolated from other geographic regions was determined on the basis of the atip and p4c genes.ResultsFennoscandian CPXV isolates encoded full length atip and p4c genes. They produce wild type V+ ATI except for CPXV-No-H2. CPXVs were resolved into six and seven species clusters based on the phylogeny of the atip and p4c genes respectively. The CPXVs isolated from Fennoscandia were grouped into three distinct clusters that corresponded to isolates from Norway, Sweden and Finland.ConclusionCPXV is a polyphyletic assemblage of six or seven distinct clusters and the current classification in which CPXVs are united as one single species should be re-considered. Our results are of significance to the classification and evolution of OPVs.