Search results for " speciation"
showing 10 items of 272 documents
Signals of demographic expansion in Drosophila virilis
2008
Background. The pattern of genetic variation within and among populations of a species is strongly affected by its phylogeographic history. Analyses based on putatively neutral markers provide data from which past events, such as population expansions and colonizations, can be inferred. Drosophila virilis is a cosmopolitan species belonging to the virilis group, where divergence times between different phylads go back to the early Miocene. We analysed mitochondrial DNA sequence variation among 35 Drosophila virilis strains covering the species' range in order to detect demographic events that could be used to understand the present characteristics of the species, as well as its differences …
Bio-sketches and partitioning of sympatric reed frogs, genusHyperolius(Amphibia; Hyperoliidae), in two humid tropical African forest regions
2004
Sympatric reed frog species were studied in Gabon (Monts Cristal: Hyperolius mosaicus, H. pardalis, H. tuberculatus) and Kenya (Kakamega Forest: Hyperolius acuticeps, H. cf. cinnamomeoventris, H. kivuensis, H. lateralis, H. viridiflavus). For each taxon, a standardized diagnosis covering 11 aspects of adult and in part tadpole morphology as well as the sequence of a 560 bp fragment of mitochondrial DNA of the 16S ribosomal gene are provided. In addition, behavioural data are given for each species including measurable parameters of advertisement calls. The Monts Cristal Hyperolius species clearly differ in their spatial arrangement through the choice of breeding site. Hyperolius species at …
The solution behavior of dopamine in the presence of mono and divalent cations: A thermodynamic investigation in different experimental conditions
2021
The interactions of dopamine [2-(3,4-Dihydroxyphenyl)ethylamine, (Dop-)] with methylmercury(II) (CH3Hg+), magnesium(II), calcium(II), and tin(II) were studied in NaCl(aq) at different ionic strengths and temperatures. Different speciation models were obtained, mainly characterized by mononuclear species. Only for Sn2+ we observed the formation of binuclear complexes (M2L2 and M2LOH (charge omitted for simplicity)
Quantitative Analysis of the Interactions of Metal Complexes and Amphiphilic Systems: Calorimetric, Spectroscopic and Theoretical Aspects.
2022
Metals and metal-based compounds have many implications in biological systems. They are involved in cellular functions, employed in the formation of metal-based drugs and present as pollutants in aqueous systems, with toxic effects for living organisms. Amphiphilic molecules also play important roles in the above bio-related fields as models of membranes, nanocarriers for drug delivery and bioremediating agents. Despite the interest in complex systems involving both metal species and surfactant aggregates, there is still insufficient knowledge regarding the quantitative aspects at the basis of their binding interactions, which are crucial for extensive comprehension of their behavior in sol…
A taxonomic revision of the Palaearctic genus Roeseliana (Orthoptera: Tettigoniidae: Tettigoniinae: Platycleidini): a case of ongoing Mediterranean s…
2023
The genus Roeseliana presently includes 10 specific or subspecific taxa, but following different authors some of them are considered synonyms. However, the authors who have treated these taxa often did not agree with the synonymies, in particular, concerning some taxa, such as R. fedtschenkoi (Saussure, 1874) and R. roeselii (Hagenbach, 1822). The present authors examined hundreds of specimens of different taxa, for the first time were able to obtain the translation from the Russian of the description of R. fedtschenkoi, compared the main morphological characters used to discriminate different taxa, biometrics, bioacoustics and genetics of some taxa. This allowed them to conclude that it is…
Does fragmentation of wetlands affect gene flow in sympatric Acrocephalus warblers with different migration strategies?
2015
Wetlands are naturally patchy habitats, but patchiness has been accentuated by the extensive wetlands loss due to human activities. In such a fragmented habitat, dispersal ability is especially important to maintain gene flow between populations. Here we studied population structure, genetic diversity and demographic history of Iberian and North African populations of two wetland passerines, the Eurasian reed warbler Acrocephalus scirpaceus and the moustached warbler Acrocephalus melanopogon. These species are closely related and sympatric in our study sites, but the reed warbler is a long-distance migrant and widespread bird while the moustached warbler is resident or migrates over short d…
Ecological divergence of closely related Diplostomum (Trematoda) parasites.
2006
Parasite life-cycles present intriguing model systems to study divergence in resource use and ecology between parasite taxa. In ecologically similar taxa, consistent selective forces may lead to convergence of life-history traits, but resource overlap and similarity of life-cycles may also promote divergence between the taxa in (1) use of host species or (2) specific niche within a host. We studied the life-history characteristics of 2 sympatric species of Diplostomum parasites, D. spathaceum and D. gasterostei, concentrating particularly on differences in intermediate host use and characteristics of the infective stages between the species. This group of trematodes is a notoriously difficu…
Evaluation of adsorption ability of Cyclodextrin-Calixarene Nanosponges towards Pb2+ ion in aqueous solution
2021
Abstract Different cyclodextrin-calixarene nanosponges (CyCaNSs) have been characterized by means of FFC-NMR relaxometry, and used as sorbents to remove Pb2+ ions from aqueous solutions. Considering that the removal treatments may involve polluted waters with different characteristics, the adsorption experiments were performed on solutions without and with the addition of background salts, under different operational conditions. The adsorption abilities and affinities of the nanosponges towards Pb2+ ions were investigated by measuring the metal ion concentration by means of Inductively Coupled Plasma Emission Spectroscopy (ICP-OES) and Differential Pulse Anodic Stripping Voltammetry (DP-ASV…
The Centetostoma scabriculum complex—a group of three cryptic species (Arachnida: Opiliones: Nemastomatidae)
2011
Nemastoma scabriculum Simon, 1879 turned out to be a group of three closely related species of the Pyrenees in SW Europe (France and Spain). Though the species are similar in general habit they can easily be recognized by external morphology (structure of the apophysis of male chelicerae) and male genital morphology (penial structure). For Nemastoma scabriculum Simon, 1879 sensu stricto a lectotype is designated. The synonymous Nemastoma ventalloi Mello-Leitao, 1936 is considered to be a distinct species and is re-described. The third species of the group is described as new, Centetostoma juberthiei sp. n. Though partly sympatric in their restricted Pyrenean area, the individual species are…
Hidden Mediterranean diversity: Assessing species taxa by molecular phylogeny within the opilionid family Trogulidae (Arachnida, Opiliones)
2009
This is the first comprehensive study to evaluate the relationships between the western palearctic harvestman families Dicranolasmatidae, Trogulidae and Nemastomatidae with focus on the phylogeny and systematics of Trogulidae, using combined sequence data of the nuclear 28S rRNA and the mitochondrial cytochrome b gene. Bayesian analysis and Maximum parsimony do not reliably resolve Dicranolasma as distinct family but place it on a similar phylogenetic level as several lineages of Trogulidae. Nemastomatidae and Trogulidae turned out to be monophyletic, as did genera Anelasmocephalus and Trogulus within the Trogulidae. The genera Calathocratus, Platybessobius and Trogulocratus each appeared p…