1,721,068 research outputs found
Isolation of novel microsatellite markers for the clouded Apollo (P-mnemosyne Linnaeus, 1758; Lepidoptera, Papilionidae)
No full textFive novel polymorphic microsatellite loci were isolated and characterized using an enriched genomic DNA library for Parnassius mnemosyne, a European butterfly of conservation concern, and a valuable model for the study of metapopulation dynamics. Allele numbers ranged from 4 to 12 and observed and expected heterozygosities from 0.17 to 0.74 and from 0.26 to 0.835, respectively. Two samples from geographically close populations were analyzed, demonstrating that the new markers can be successfully employed to investigate fine-scale population structure
Combined kinetic and spectroscopic study of oxidation of azo dyes in surfactant solutions by hypochlorite
No full textCombined kinetic, spectroscopic and thermodynamic investigations have been carried out to examine the influence of cationic, anionic and nonionic surfactants upon the oxidation of an azo dye, II, by hypochlorite. Oxidation rates were unaffected by the presence of anionic or nonionic surfactant (SDS or C12E5) either in micellar or submicellar regions: indicating the absence of any specific dye-surfactant interactions. On the other hand, specific interactions were observed with cationic surfactants, both in submicellar and micellar regions. Addition of CTAts to dye II produced a reduction in intensity of its UV-vis spectrum and caused oxidation rates to decrease. These are attributed to formation of a sparingly soluble 1:1 complex with the dye, via interactions with the sulfonate groups. Binding of DTAC to the dye in sub-micellar regions results in a slight enhancement in oxidation rates, which is attributed to break-up of small, soluble dye aggregates. In micellar regions, there was evidence that the dye becomes incorporated into the surface of micelles formed by both cationic surfactants, where they become inert to reaction with hypochlorite
Pleistocene evolutionary history of the Clouded Apollo (Parnassius mnemosyne): genetic signatures of climate cycles and a 'time-dependent' mitochondrial substitution rate
Full text linkGenetic data are currently providing a large amount of new information on past distribution of species and are contributing to a new vision of Pleistocene ice ages. Nonetheless, an increasing number of studies on the 'time dependency' of mutation rates suggest that date assessments for evolutionary events of the Pleistocene might be overestimated. We analysed mitochondrial (mt) DNA (COI) sequence variation in 225 Parnassius mnemosyne individuals sampled across central and eastern Europe in order to assess (i) the existence of genetic signatures of Pleistocene climate shifts; and (ii) the timescale of demographic and evolutionary events. Our analyses reveal a phylogeographical pattern markedly influenced by the Pleistocene/Holocene climate shifts. Eastern Alpine and Balkan populations display comparatively high mtDNA diversity, suggesting multiple glacial refugia. On the other hand, three widely distributed and spatially segregated lineages occupy most of northern and eastern Europe, indicating postglacial recolonization from different refugial areas. We show that a conventional 'phylogenetic' substitution rate cannot account for the present distribution of genetic variation in this species, and we combine phylogeographical pattern and palaeoecological information in order to determine a suitable intraspecific rate through a Bayesian coalescent approach. We argue that our calibrated 'time-dependent' rate (0.096 substitutions/million years), offers the most convincing time frame for the evolutionary events inferred from sequence data. When scaled by the new rate, estimates of divergence between Balkan and Alpine lineages point to c. 19 000 years before present (last glacial maximum), and parameters of demographic expansion for northern lineages are consistent with postglacial warming (5-11 000 years before present)
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 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
Accounting for pseudoreplication is not possible when the source of nonindependence is unknown
No full textRepeated observations of the same individuals or other units, which can lead to clustered observations, are common in animal behaviour research, and mixed models are commonly employed to model and account for such clustering in the data and avoid pseudoreplication. However, in some cases, while the data might comprise repeated samples from the same individuals, the precise identity of the individuals from which samples originated is unknown. In a recent paper Garamszegi (2016, Animal Behaviour, 120, 223–234) suggested an approach to account for pseudoreplication which is based on repeatedly assigning random subject identities to the samples and then analysing the data using a mixed model or averaged values for each randomly assigned identity. Here we tested this approach using a simulation study. We found that the approach suggested by Garamszegi leads to clearly inflated type I error rates that were essentially the same as those obtained from a naïve linear model simply ignoring individual identity and that only a model based on the correct subject identities roughly produced the nominal type I error rate. We conclude that, currently, there is no method available that allows pseudoreplication to be controlled when subject identities are unknown
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Nothing but a trace left? Autochthony and conservation status of Northern Adriatic Salmo trutta inferred from PCR multiplexing, mtDNA control region sequencing and microsatellite analysis
No full textPhylogeny of Northern Adriatic Salmo trutta is still not resolved, leading to taxonomic controversies and hindering reasonable conservation and fisheries management. We report on the genetic screening of 467 brown trout from 25 sites within Adige, Brenta and Po River drainage basins (Italy). Our main aim was to identify native (Adriatic) brown trout within the central part of the Northern Adriatic area. D-loop lineage screening evidenced a predominance of the Atlantic clade with a frequency of 0.87, followed by the Marmoratus clade with 0.11, and, finally, the Adriatic clade with a frequency of 0.02. The Adriatic clade was found exclusively in specimens from Pianetti River and was represented by haplotype Adcs1. However, microsatellite-based analysis of population structure within Pianetti River specimens failed to identify Adriatic brown trout, but pointed to a nuclear genomic replacement of the former by Atlantic strains. In conjunction with earlier phylogenetic studies, our results contrast with a present-day widespread distribution scenario of Adriatic brown trout within the Northern Adriatic region. From a conservation viewpoint, the punctiform occurrence of Adriatic haplotypes, their ambiguous provenance, and, finally, the presumable genomic replacement at the nuclear genetic level, might hinder reasonable conservation actions and call for revised fisheries management guidelines
Kinetic and spectroscopic study of heterogeneous oxidation of azo dyes using hypochlorite
No full textA combined kinetic and spectroscopic investigation is described of the heterogeneous oxidation (by hypochlorite) of an azo dye (Remazol Red RB) reactively bound to cotton. It is shown that the physical state of bound dye (e.g. its pK(A) and tautomeric form) and its oxidation profile with pH are similar to those or dye in homogeneous solution. Analyses are presented which suggest that the mechanism of oxidation in the two environments is similar. The oxidation of azo dyes of pyrazolone and pyridone types occurs at similar rates to arylazonaphthol dyes. This suggests that oxidation kinetics are independent of groups attached either side of the azo linkage, confirming that the site of attack is the more nucleophilic nitrogen atom of the azo group of the common anion
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