Phylogeny of Annelida (Lophotrochozoa): total-evidence analysis of morphology and six genes

<p>Abstract</p> <p>Background</p> <p>Annelida is one of the major protostome phyla, whose deep phylogeny is very poorly understood. Recent molecular phylogenies show that Annelida may include groups once considered separate phyla (Pogonophora, Echiurida, and Sipunculida) and that Clitellata are derived polychaetes. SThe "total-evidence" analyses combining morphological and molecular characters have been published for a few annelid taxa. No attempt has yet been made to analyse simultaneously morphological and molecular information concerning the Annelida as a whole.</p> <p>Results</p> <p>Phylogenetic relationships within Annelida were analysed on the basis of 93 morphological characters and sequences of six genes (<it>18S</it>, <it>28S</it>, and <it>16S rRNA</it>, <it>EF1α</it>, <it>H3</it>, <it>COI</it>), altogether, 87 terminals of all annelid "families" and 3,903 informative characters, by Bayesian and maximum-parsimony methods. The analysis of the combined dataset yields the following scheme of relationships: Phyllodocida and Eunicida are monophyletic groups, together probably forming monophyletic Aciculata (incl. Orbiniidae and Parergodrilidae that form a sister group of the Eunicida). The traditional "Scolecida" and "Canalipalpata" are both polyphyletic, forming instead two clades: one including Cirratuliformia and the "sabelloid-spionoid clade" (incl. <it>Sternaspis</it>, Sabellidae-Serpulidae, Sabellariidae, Spionida s.str.), the other ("terebelloid-capitelloid clade") including Terebelliformia, Arenicolidae-Maldanidae, and Capitellidae-Echiurida. The Clitellata and "clitellate-like polychaetes" (Aeolosomatidae, Potamodrilidae, <it>Hrabeiella</it>) form a monophyletic group. The position of the remaining annelid groups is uncertain – the most problematic taxa are the Opheliidae-Scalibregmatidae clade, the Amphinomida-<it>Aberranta </it>clade, <it>Apistobranchus</it>, Chaetopteridae, Myzostomida, the Sipunculida-Dinophilidae clade, and the "core Archiannelida" (= Protodrilidae, Nerillidae, Polygordiidae, Saccocirridae).</p> <p>Conclusion</p> <p>The combined ("total-evidence") phylogenetic analysis provides a modified view of annelid evolution, with several higher-level taxa, i.e. Phyllodocida, Eunicida, orbinioid-parergodrilid clade (OPC), Cirratuliformia, sabelloid-spionoid clade (SSC), terebelloid-capitelloid clade (TCC), and "Clitellatomorpha". Two unorthodox clades, the "core Archiannelida" and Sipunculida-Dinophilidae, are proposed. Although the deep-level evolutionary relationships of Annelida remain poorly understood, we propose the monophyly of the Aciculata, sister-group relationships between the Eunicida and OPC, between the Cirratuliformia and SSC, and possibly also between the "Clitellatomorpha" and Oweniidae-Pogonophora clades.</p

Crenicichla hu, a new species of cichlid fish (Teleostei: Cichlidae) from the Paraná basin in Misiones, Argentina

A new species of Crenicichla Heckel, C. hu, is described from the arroyo Piray–Miní, a left-hand tributary of the río Paraná, Misiones province, Argentina. This new species is easily distinguished from its congeners in the La Plata basin and adjacent coastal rivers by the dark coloration (dark grey or dark brown to black), a color pattern consisting of 7 to 9 black irregular blotches on the flank, and 47–54 scales in the E1 row. Adult females have dorsal fin with an irregular color pattern formed by wide black and white longitudinal stripes and blotches. In addition to standard morphological comparisons, a brief molecular phylogenetic analysis of Crenicichla species from the province of Misiones is also introduced.Facultad de Ciencias Naturales y Muse

Two new species of Australoheros (Teleostei: Cichlidae), with notes on diversity of the genus and biogeography of the Río de la Plata basin

Two new species of Australoheros Říčan and Kullander are described. Australoheros ykeregua sp. nov. is described from the tributaries of the río Uruguay in Misiones province, Argentina. Australoheros angiru sp. nov. is described from the tributaries of the upper rio Uruguai and middle rio Iguaçu in Brazil. The two new species are not closely related, A. ykeregua is the sister species of A. forquilha Říčan and Kullander, while A. angiru is the sister species of A. minuano Říčan and Kullander. The diversity of the genus Australoheros is reviewed using morphological and molecular phylogenetic analyses. These analyses suggest that the described species diversity of the genus in the coastal drainages of SE Brazil is overestimated and that many described species are best undestood as representing cases of intraspecific variation. The distribution patterns of Australoheros species in the Uruguay and Iguazú river drainages point to historical connections between today isolated river drainages (the lower río Iguazú with the arroyo Urugua–í, and the middle rio Iguaçu with the upper rio Uruguai). Molecular clocks are used to date these and other biogeographic patterns.Facultad de Ciencias Naturales y Muse

A new pelagic predatory pike cichlid (Teleostei: Cichlidae: Crenicichla ) from the C. mandelburgeri species complex with parallel and reticulate evolution

The Crenicichla mandelburgeri species complex from the Middle Parana shows parallel evolution of ecomorphs to the unrelated C. missioneira species complex from the Uruguay River. In this article, we describe a new species from the C. mandelburgeri species complex that has evolved a parallel morphology and ecology to an unrelated species from the C. missioneira species complex (C. celidochilus). The new species is a pelagic predator that feeds predominantly on fishes and together with C. celidochilus is the only known pelagic species in the large riverine genus Crenicichla. The new species is endemic solely to a small tributary (the Urugua-i) of the Middle Parana River where it is sympatric and partly syntopic with two other closely related endemic species that, however, differ strongly in their ecomorphologies (one is a generalistic invertivore and the other a specialized molluscivore). Mitochondrial DNA phylogeny finds the new species nested within the widespread C. mandelburgeri. Reduced genome-representation ddRAD analyses, however, demonstrate that this new species is of a hybrid origin and shares ancestry with C. ypo, one of the two studied sympatric species.Facultad de Ciencias Naturales y MuseoComisión de Investigaciones Científicas de la provincia de Buenos Aire

First records of <i>Characidium heirmostigmata</i> and <i>C. serrano</i> (Characiformes: Crenuchidae) from freshwaters of Argentina

Characidium heirmostigmata and C. serrano are registered for the first time in freshwaters of Argentina in the province of Misiones. Characidium heirmostigmata was found in the middle río Paraná basin and C. serrano in upper and middle río Uruguay basin.Facultad de Ciencias Naturales y Muse

First records of <i>Characidium heirmostigmata</i> and <i>C. serrano</i> (Characiformes: Crenuchidae) from freshwaters of Argentina

Characidium heirmostigmata and C. serrano are registered for the first time in freshwaters of Argentina in the province of Misiones. Characidium heirmostigmata was found in the middle río Paraná basin and C. serrano in upper and middle río Uruguay basin.Facultad de Ciencias Naturales y Muse

Multilocus phylogeny of Crenicichla (Teleostei: Cichlidae), with biogeography of the C. lacustris group: Species flocks as a model for sympatric speciation in rivers

First multilocus analysis of the largest Neotropical cichlid genus Crenicichla combining mitochondrial (cyt. b, ND2, 16S) and nuclear (S7 intron 1) genes and comprising 602 sequences of 169 specimens yields a robust phylogenetic hypothesis. The best marker in the combined analysis is the ND2 gene which contributes throughout the whole range of hierarchical levels in the tree and shows weak effects of saturation at the 3rd codon position. The 16S locus exerts almost no influence on the inferred phylogeny. The nuclear S7 intron 1 resolves mainly deeper nodes. Crenicichla is split into two main clades: (1) Teleocichla, the Crenicichla wallacii group, and the Crenicichla lugubris- Crenicichla saxatilis groups (" the TWLuS clade"); (2) the Crenicichla reticulata group and the Crenicichla lacustris group- Crenicichla macrophthalma (" the RMLa clade"). Our study confirms the monophyly of the C. lacustris species group with very high support. The biogeographic reconstruction of the C. lacustris group using dispersal-vicariance analysis underlines the importance of ancient barriers between the middle and upper Paraná River (the Guaíra Falls) and between the middle and upper Uruguay River (the Moconá Falls). Our phylogeny recovers two endemic species flocks within the C. lacustris group, the Crenicichla missioneira species flock and the herein discovered Crenicichla mandelburgeri species flock from the Uruguay and Paraná/Iguazú Rivers, respectively. We discuss putative sympatric diversification of trophic traits (morphology of jaws and lips, dentition) and propose these species flocks as models for studying sympatric speciation in complex riverine systems. The possible role of hybridization as a mechanism of speciation is mentioned with a recorded example (Crenicichla scottii).Museo de La Plat

First record of Rineloricaria reisi, R. stellata and R. zaina (Siluriformes: Loricariidae) from the Río Uruguay basin in Argentina

Rineloricaria reisi, R. stellata, and R. zaina are registered for the first time in freshwaters of Argentina. These three species were found in the Río Uruguay basin in Misiones Province. As a result of these findings, five species of Rineloricaria are found in the Río Uruguay basin in Argentina. A key of Rineloricaria species from that basin is also provided

Genetic conflict outweighs heterogametic incompatibility in the mouse hybrid zone?

<p>Abstract</p> <p>Background</p> <p>The <it>Mus musculus musculus/M. m. domesticus </it>contact zone in Europe is characterised by sharp frequency discontinuities for sex chromosome markers at the centre of wider clines in allozyme frequencies.</p> <p>Results</p> <p>We identify a triangular area (approximately 330 km²) where the <it>musculus </it>Y chromosome introgresses across this front for up to 22 km into <it>domesticus </it>territory. Introgression of the Y chromosome is accompanied by a perturbation of the census sex ratio: the sex ratio is significantly female biased in <it>musculus </it>localities and <it>domesticus </it>localities lacking Y chromosome introgression. In contrast, where the <it>musculus </it>Y is detected in <it>domesticus </it>localities, the sex ratio is close to parity, and significantly different from both classes of female biased localities. The geographic position of an abrupt cline in an X chromosome marker, and autosomal clines centred on the same position, seem unaffected by the <it>musculus </it>Y introgression.</p> <p>Conclusion</p> <p>We conclude that sex ratio distortion is playing a role in the geographic separation of speciation genes in this section of the mouse hybrid zone. We suggest that clines for genes involved in sex-ratio distortion have escaped from the centre of the mouse hybrid zone, causing a decay in the barrier to gene flow between the two house mouse taxa.</p

Multilocus phylogeny of Crenicichla (Teleostei: Cichlidae), with biogeography of the C. lacustris group: Species flocks as a model for sympatric speciation in rivers

First multilocus analysis of the largest Neotropical cichlid genus Crenicichla combining mitochondrial (cyt. b, ND2, 16S) and nuclear (S7 intron 1) genes and comprising 602 sequences of 169 specimens yields a robust phylogenetic hypothesis. The best marker in the combined analysis is the ND2 gene which contributes throughout the whole range of hierarchical levels in the tree and shows weak effects of saturation at the 3rd codon position. The 16S locus exerts almost no influence on the inferred phylogeny. The nuclear S7 intron 1 resolves mainly deeper nodes. Crenicichla is split into two main clades: (1) Teleocichla, the Crenicichla wallacii group, and the Crenicichla lugubris- Crenicichla saxatilis groups (" the TWLuS clade"); (2) the Crenicichla reticulata group and the Crenicichla lacustris group- Crenicichla macrophthalma (" the RMLa clade"). Our study confirms the monophyly of the C. lacustris species group with very high support. The biogeographic reconstruction of the C. lacustris group using dispersal-vicariance analysis underlines the importance of ancient barriers between the middle and upper Paraná River (the Guaíra Falls) and between the middle and upper Uruguay River (the Moconá Falls). Our phylogeny recovers two endemic species flocks within the C. lacustris group, the Crenicichla missioneira species flock and the herein discovered Crenicichla mandelburgeri species flock from the Uruguay and Paraná/Iguazú Rivers, respectively. We discuss putative sympatric diversification of trophic traits (morphology of jaws and lips, dentition) and propose these species flocks as models for studying sympatric speciation in complex riverine systems. The possible role of hybridization as a mechanism of speciation is mentioned with a recorded example (Crenicichla scottii).Museo de La Plat