Salenthydrobia gen. nov. (Rissooidea: Hydrobiidae): a potential relict of the Messinian salinity crisis

The Messinian salinity crisis (MSC) occurred synchronously throughout the Mediterranean basin about 5.96 ± 0.02 Mya and represents one of the most dramatic oceanic changes since the early Miocene. It is thought that the concomitant environmental changes brought about isolation of faunas and the development of endemism. As part of the search for possible speciation events triggered by the MSC, the author studied 38 populations of hydrobiine snails from the Mediterranean and Black Sea, including three populations from the Salentina Peninsula, Italy. Partial sequences (COI, 16S) and anatomical data were used to test the taxonomic and phylogenetic status of the peninsular populations. A maximum likelihood analysis of 11 hydrobiine taxa revealed five clades and lineages, four of which corresponded to previously recognized genera: Adriohydrobia , Hydrobia , Peringia , Ventrosia . The fifth clade was formed by haplotypes of the peninsular populations, which are characterized by distinct male and female reproductive systems. Based on molecular and anatomical data, these populations are considered to represent a new species, Salenthydrobia ferrerii , belonging to a new genus, Salenthydrobia . Ecological and biogeographical data for S. ferrerii strongly support a correlation between its origin and the MSC. Based on an island age of 5.33 Myr and a population divergence of 0.0973 ± 0.0114, the COI molecular clock rate for the Salenthydrobia and Peringia clades would be 1.83 ± 0.21% population divergence per Myr. The genetic diversity of S. ferrerii , its phylogenetic relationships, and the validity of the proposed local molecular clock rate are discussed.     

Molecular identification and phylogenetic relationships of seven Indian Sciaenids (Pisces: Perciformes,Sciaenidae) based on 16S rRNA and cytochrome c oxidase subunit I mitochondrial genes

The partial sequences of 16S rRNA and cytochrome c oxidase subunit I (COI) mitochondrial genes were analyzed for species identification and phylogenetic relationships among the commercially important Indian sciaenids (Otolithes cuvieri, Otolithes ruber, Johnius dussumieri, Johnius elongatus, Johnieops vogleri, Otolithoides biauritus and Protonibea diacanthus). Sequence analysis of both genes revealed that the seven species fell into three distinct groups, which were genetically distant from each other and exhibited identical phylogenetic resolution. Partial sequences of both the genes provided sufficient phylogenetic information to distinguish the seven sciaenids indicating the usefulness of mtDNA-based approach in species identification.     

Problems with DNA barcodes for species delimitation: ‘Ten species’ of Astraptes fulgerator reassessed (Lepidoptera: Hesperiidae)

Hebert and colleagues (2004) used a short region of the mitochondrial Cytochrome oxidase subunit I gene as a delimiter for ten putative species from among 466 individuals of the skipper butterfly currently known as Astraptes fulgerator from Guanacaste, Costa Rica. Their data are reanalysed to assess cluster stability and clade support using Neighbor‐Joining bootstrap, population aggregation analysis and cladistic haplotype analysis. At least three, but not more than seven mtDNA clades that may correspond to cryptic species are supported by the evidence. Additional difficulties with Hebert et al.’s interpretation of the data are discussed.     

Genetic relatedness among fish species of Genus Channa using mitochondrial DNA genes

The family Channidae is represented by 26 species, out of which 23 species are found in Asia. However, the taxonomy and phylogeny of the Channid fishes found in India are poorly understood. In the present study, eight species of Channa (Channa striata, Channa punctatus, Channa marulius, Channa gachua, Channa stewartii, Channa aurantimaculata, Channa barca and Channa bleheri) were investigated using partial sequences of 16S rRNA and Cytochrome c Oxidase subunit I (COI) of mitochondrial genes to differentiate among the eight species and study their relationships. The sequence analysis of the genes revealed two distinct groups, which are genetically distant from each other and exhibit identical phylogenetic resolution. The partial sequences of both the genes provided sufficient phylogenetic information to distinguish all the eight species of Channa.     

Hybridization and recurrent evolution of left–right reversal in the land snail genus Schileykula (Orculidae,Pulmonata)

The land snail genus Schileykula Gittenberger, 1983 is distributed in arid limestone areas from western Turkey to north-western Iran. It comprises eight species, which display high variation in shell size and morphology. The cylindrical shells are 5–12 mm in height and the last shell whorls bear several inner lamellae and plicae. Two taxa differ in their chirality having sinistral shells, while all the others are dextrals such as the vast majority of orculids. The aim of this study was to establish a molecular genetic phylogeny of Schileykula and to test whether it conforms to the current morphology-based classification. Furthermore, we were interested in the phylogenetic position of the two sinistral forms in order to assess whether one or two reversals happened in the evolution of the genus. Nine out of ten species, including all four subspecies of Schileykula trapezensis and three of six subspecies of Schileykula scyphus, were investigated. A section of the mitochondrial cytochrome c oxidase subunit I gene was analyzed in 54 specimens of Schileykula and from a subsample, partial sequences of the mitochondrial genes for the 12S rRNA and the 16S rRNA, and a section of the nuclear H4/H3 histone gene cluster were obtained. The phylogenetic trees based on the mitochondrial sequences feature high support values for most nodes, and the species appear well differentiated from each other. The two chiral forms evolved independently and are not sister lineages. However, some groupings disagree with the present morphology-based classification and taxonomical conclusions are drawn. Schileykula trapezensis is polyphyletic in the molecular genetic trees; therefore, three of its subspecies are elevated to species level: Schileykula acampsis Hausdorf, 1996 comb. nov., Schileykula neuberti Hausdorf, 1996 comb. nov., and Schileykula contraria Neubert, 1993 comb. nov. Furthermore, Schileykula sigma is grouped within S. scyphus in the mitochondrial and nuclear trees and consequently treated as a subspecies of the latter (Schileykula scyphus sigma Hausdorf, 1996 comb. nov.). Schileykula nordsiecki, whose shell morphology is indistinguishable from that of the neighboring Schileykula scyphus lycaonica, but who differs in its genital anatomy, was confirmed to represent a distinct lineage. The phylogenies produced by the mitochondrial and nuclear data sets are to some extent conflicting. The patterns differ concerning the grouping of some specimens, suggesting at least two independent hybridization events involving S. contraria, S. scyphus and S. trapezensis. The results exemplify the importance of integrating both mitochondrial and nuclear sequence data in order to complement morphology-based taxonomy, and they provide further evidence for hybridization across distantly related lineages in land snails.     

Coming to America: multiple origins of New World geckos

Geckos in the Western Hemisphere provide an excellent model to study faunal assembly at a continental scale. We generated a time-calibrated phylogeny, including exemplars of all New World gecko genera, to produce a biogeographical scenario for the New World geckos. Patterns of New World gecko origins are consistent with almost every biogeographical scenario utilized by a terrestrial vertebrate with different New World lineages showing evidence of vicariance, dispersal via temporary land bridge, overseas dispersal or anthropogenic introductions. We also recovered a strong relationship between clade age and species diversity, with older New World lineages having more species than more recently arrived lineages. Our data provide the first phylogenetic hypothesis for all New World geckos and highlight the intricate origins and ongoing organization of continental faunas. The phylogenetic and biogeographical hypotheses presented here provide an historical framework to further pursue research on the diversification and assembly of the New World herpetofauna.