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Insights into the molecular phylogeny of Rhaphidophoridae, an ancient, worldwide lineage of Orthoptera
No full textWe investigated the molecular phylogenetic divergence and historical biogeography of cave crickets belonging to the family Rhaphidophoridae (Orthoptera, Ensifera). We used taxa representative of most of the regions embraced by the family, considering samples of Macropathinae from Gondwana land (i.e., Tasmania, Australia, New Zealand, South Africa, and South America); Aemodogryllinae and Rhaphidophorinae from Southern-eastern Asia (i.e., India, Bhutan, China, Philippines and the Sulawesi islands); Dolichopodainae and Troglophilinae from the Mediterranean region and Ceuthophilinae from North America. Based on previous papers, we carried out an analysis of both mitochondrial and nuclear DNA sequences considering the ribosomal RNA units 12S, 16S, 18S, and 28S. To reconstruct phylogeny, we use cladistics, Maximum Likelihood (ML), and Bayesian analyses. All phylogenetic analyses showed the same highly supported topology generally congruent with the classical systematic arrangement at the level of each sub-family but strongly disagree with previous affinity hypotheses between sub-families based on morphological characters. Our results reveal a close affinity between Asiatic and Gondwanian taxa from one hand and between North American and Mediterranean ones from the other hand. Dating estimates indicated that Rhaphidophoridae originated in the Cretaceous period during the Mesozoic era with the ancestral area located both in the northern and southern hemisphere. A possible biogeographic scenario, reconstructed using S-DEC with RASP software, suggested that the current distribution of Rhaphidophoridae might be explained by a combination of both dispersal and vicariance events occurred especially in the ancestral populations. The radiation of Rhaphidophoridae started within the Pangaea, where the ancestor of Rhaphidophoridae occurred throughout an ancestral area including Australia, North America, and the Mediterranean region. The opening of the Atlantic Ocean promoted the divergence of North American and Mediterranean lineages while the differentiation of the southern lineages, spread from Australia, appears to be related to the fragmentation of Gondwana land
Congruence between molecular and morphological systematics of Alpine non-biting midges (Chironomidae, Diamesinae)
No full textIn mountain regions, climate change is resulting in glacial retreat, causing biodiversity loss in glacial-fed streams (kryal habitat). Diamesa species (Diptera Chironomidae), the main colonizers of the kryal in the Alps, are the aquatic insects more threatened by extinction. In recent years, DNA barcoding was successfully adopted to delimit species of chironomids and provided species identification. We highlighted that for the Diamesa genus, inconsistencies remain between identification on a morphological and molecular basis, mainly within cinerella and zernyi groups, raising doubts about the validity of head colour as a good diagnostic taxonomic character. Molecular phylogeny reconstruction based on mitochondrial (cytochrome oxidase subunits I and II) and one nuclear (ribosomal 18S rRNA) markers revealed that D. bohemani and D. zernyi on one hand, and D. cinerella and D. tonsa on the other hand, represent populations of the same species. Divergence times suggested that the radiation of these alpine species seems to have been driven by the climatic events with the alternation of glacial periods that happened in the Pliocene and Pleistocene. The initial separation of the oriental species D. steinboecki seems to be due to the tectonic movements of the Periadriatic fault system that probably favoured the emergence of lakes and streams, successively colonized by D. steinboecki. This study raises important concerns, from the validity of diagnostic characters used today to identify larval types up to the uncertainty about how many species of Diamesa inhabit the European Alps and what their fate will be within the scenario of climate change
Multivariate analysis of multi-character individual profiles as a tool in systematics
No full textThe biological concept of species, which considers either reproductive isolation or the recognition mating system as criteria for the species definition, suffers several operational difficulties. Reproductive isolation can be seldom demonstrated, especially when hybridization and introgressive phenomena occur, when populations are allopatric, and in non-amphigonically reproducing organisms. In such situations, traditional populational approaches may present problems and the description of taxonomic samples or their variability as averages, variances, or frequencies may be inadeguate. Multivariate ordination techniques may be usefully applied to individual data sets. This method offers several advantages in clarifying systematic and evolutionary relationships among demes, populations or species. First, it makes possible to evaluate the relative location of each individual with respect to various character sets with different properties. Second, it makes possible an identification a posteriori of each individual as <<belonging to>> or <<different from>> a specific cluster. Third, it makes possible to establish relative similarity among taxa within a reference system which is not deformed by cluster algorithms or a priori established character states. Finally, it provides essential indication on the most reliable taxonomic characters to be considered for current systematic work. Two study examples are reported to illustrate the usefulness of this kind of approach in natural situations, where hybridization and introgression occur
Geographic variation and genetic relationships in populations of the Androniscus dentiger complex from Central Italy (Isopoda, Oniscidea, Trichoniscidae)
No full textAndroniscus dentiger is a terrestrial isopod distributed from Great Britain to North Africa, inhabiting humid edafic environments, superficial underground compartments and both natural and artificial caves. In this study allozyme data have been used to investigate the geographic variation and the genetic relationships of several populations of A. dentiger from Central Italy, using as outgroups populations from four congeneric species, A. calcivagus, A. cfr. subterraneus, A. spelaeorum, and A. degener. Multivariate analysis of A. dentiger allele frequencies indicates the existence of a group of populations (group A) distributed in a wide geographic area which are genetically slightly differentiated, and several populations (arbitrarily defined as group B) which show differentiation levels comparable to those observed between the morphologically well differentiated species. The low valley of the river Tiber seems to act as an effective geographic barrier between the populations from group A and the remaining ones. The genetic divergence between populations within the group A seems to have a recent origin. This is suggested by the low genetic distances and heterozygosity values within the group A, and by the very low number of private alleles occurring in this group. The high degree of intraspecific and interspecific genetic differentiation is not consistent with the levels of morphological differentiation traditionally used to distinguish different species within this genus. On the whole, these data suggest that A. dentiger might be considered as a complex of cryptic/sibling species
Three new species of Bathysciola Jeannel, 1910 (Leiodidae, Cholevinae, Leptodirini) from caves in Central Italy, comparing morphological taxonomy with molecular phylogeny
No full textThe genus Bathysciola is widely distributed in the northern Mediterranean region, although its range extends east to the Caucasus and Iran. More than 130 species belonging to this genus are actually known in the whole geographic distribution area and 45 species are distributed in continental and insular Italy. The species belonging to the Bathysciola sisernica
Cerruti and Patrizi, 1952 species group occur in the Central-Southern Italian Apennines and Pre-Apennines. This group consists of seven species, four of which (B. sisernica, B. delayi Latella and Rampini, 1994, B. rampinii
Latella, 2002, B. sbordoni Rampini and Latella, 1993) were already known to science and three are described herein, Bathysciola fabiolae
sp. nov., Bathysciola octaviani
sp. nov.
, and Bathysciola valeriae
sp. nov., markedly increasing the knowledge on the distribution of this genus in Central Italy. A morphological analysis was carried out based on diagnostic characters usually used to distinguish different taxa, and including both genitalia and external traits. Based on morphological characters, we reconstructed the phylogeny of this group of species, comparing them with the species belonging to other phyletic lineages, such as B. derosasi
Jeannel, 1914, B. georgi Cerruti, Patrizi, 1952, B. vignai Sbordoni and Rampini, 1978, and B. sarteanensis sarteanensis (Bargagli, 1870). Results suggested that morphological traits show a clear taxonomic signal but a poor phylogenetic signal. To better understand the relationships within this group of species, we performed a molecular analysis by sequencing three mitochondrial genes, 12S rRNA, 16S rRNA, partially sequenced and the entire gene of COI. Molecular markers were used to infer phylogenetic relationships among the Bathysciola sisernica species group and to reconstruct the historical processes that shaped their current geographic distribution. Results showed that these species became isolated in very ancient times, showing very high genetic differentiation.</jats:p
The evolutionary jigsaw puzzle of the surviving trout (Salmo trutta L. complex) diversity in the Italian region. A multilocus Bayesian approach.
No full textMediterranean trout populations display a diversity of phenotypes, representing a valuable model for the
study of adaptation and a puzzling dilemma for taxonomists and biogeographers, which is further entangled
by the widespread introgression of allochthonous genes.
In this paper we analysed DNA polymorphism at multiple loci (sequence variation of the mitochondrial
control region and eight nuclear fragments and length variation at eleven nuclear microsatellite loci) in
representative samples of the autochthonous taxonomic diversity described in Italian trout populations
(Salmo marmoratus, S. carpio, S. cenerinus, S. cettii and S. fibreni) and in samples from hatchery-originated
strains of Atlantic S. trutta. We employed model-based clustering and Approximate Bayesian Computation
in order to: (i) describe the phylogeographic structure of Italian autochthonous trout populations;
(ii) evaluate a set of evolutionary/biogeographic models. The inclusion of hatchery-originated strains
allowed to account for man-mediated allochthonous introgression in Italian populations.
Our results (i) showed that the analysed sample consists of two main autochthonous evolutionary lineages,
including the marble trout populations on one side (‘marble’ lineage) and the three peninsular
populations of S. cettii, S. cenerinus and S. fibreni on the other side (‘peninsular’ lineage); (ii) indicated that
S. carpio originated from a ‘peninsular’ population, with a possible, limited contribution from the ‘marble’
lineage; (iii) pointed out that the ‘marble’ lineage started diverging before the separation of the ‘peninsular’
lineage from Atlantic S. trutta; (iv) suggested that a model of divergence involving gene flow from
the ‘peninsular’ population into the ancestral gene pool of ‘marble’ trout is most consistent with the
genetic data; (v) provided evidence that the autochthonous trout gene pools in the Tyrrhenian and Adriatic
basins of the Italian peninsula started diverging very recently (most likely after the last glacial
maximum)
Genetic structure and allozyme variation of sea bass (Dicentrarchus labrax and D-punctatus) in the Mediterranean Sea
No full textThis paper reports data on 28 allozyme loci in wild and artificially reared sea bass (Dicentrarchus labrax) samples, originating from either coastal lagoon or marine sites in the Mediterranean Sea. F-ST analysis (theta estimator) indicated strong genetic structuring among populations; around 34% of the overall genetic variation is due to interpopulation variation. Pairwise theta estimates showed that, on average, the degree of genetic structuring was much higher between marine populations than between samples from lagoons. Six polymorphic loci showed differences in allele frequencies between marine and lagoon samples. Multivariate analyses of individual allozymic profiles and of allele frequencies suggested that different arrays of genotypes prevail in lagoons compared to marine samples, particularly at those loci that, on the basis of previous acclimation experiments, had been implicated in adaptation to freshwater. On the other hand, variation at ''neutral'' allozyme loci reflects to a greater extent the geographic location of populations. Allozyme differentiation was also studied in a D. labrax population from the Portuguese coast. Average genetic distance between this population and the Mediterranean populations was quite high (Nei's D = 0.236) and calls into question the taxonomic status of the Portuguese population. Finally, genetic relationships between D. labrax and D. punctatus were evaluated. Average Nei's D was 0.648, revealing high genetic differentiation between the two species, even for two sympatric populations of these species in Egypt; thus gene flow was not indicated between species
Genetic differentiation and hybridization in two naturally occurring sympatric trout Salmo spp. forms from a small karstic lake.
Full text linkIn this study, multiple molecular markers [genotyping of 12 nuclear microsatellite loci and the
protein-coding gene ldh-c1 * plus sequencing of the mitochondrial DNA (mtDNA) control region]
were employed to investigate the genetic structure of the two trout forms, Salmo cettii and Salmo
fibreni , inhabiting Lake Posta Fibreno, central Italy. The two forms were found to share a unique
mtDNA haplotype, belonging to a widespread Mediterranean haplogroup (AD). Bayesian clustering
analyses showed that these two forms correspond to well-defined autochthonous gene pools. Genetic
introgression between the two gene pools, however, was observed, whose frequency appears to
correlate with the environmental features of the spawning sites. The interplay of selection for the
spawning sites, philopatry and natural selection can be argued to maintain genetic differentiation
despite the lack of complete reproductive isolation
Cytochrome b sequence divergence in the European sea bass (Dicentrarchus labrax) and phylogenetic relationships among some Perciformes species
No full textThe entire cytochrome b (cyt b) gene has been sequenced in eight Mediterranean populations of the European sea bass, Dicentrarchus labrax and in one of D. punctatus. Our data indicate that both eastern (Greece and Egypt) and northwestern (French coast) populations of D. labrax were genetically differentiated from the Tyrrhenian ones, which were nearly indistinguishable from each other at the cyt b level. The D. labrax population from the Atlantic coast (Portugal) was genetically quite distinct from all the Mediterranean ones. These results strongly confirm the conclusions from previous studies where the same populations were screened for allozymes, random amplified polymorphic DNA (RAPD) and mitochondrial DNA (mtDNA) D-loop variation. Seven other species of Perciformes belonging to five different families (Sparidae, Serranidae, Carangidae, Pomatomidae, Sciaenidae) were sequenced to explore the usefulness of the cyt b gene for inferring evolutionary relationships at different hierarchical levels. The data were analysed together with other published cyt b sequences from Perciformes fishes. Our data suggest thar the superfamily Percoidea is not monophyletic. At the family level, the Sparidae and Moronidae seem to be monophyletic. The evolutionary relationships among families were not resolved. Possible causes for this lack of resolution are discussed
Population genetic structure and geographic variation in the troglophilic woodlouse Androniscus dentiger from Central Italy.
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