1,721,160 research outputs found
MOLECULAR SYSTEMATICS AND THE MULTIDIMENSIONAL CONCEPT OF SPECIES
No full textFollowing a critical review of the species concepts and stressing the need for a single, general classification system to serve both systematists and evolutionary biologists, the author seeks to identify a conceptual framework where matching of taxonomic characters to the biological properties of species is maximized. Sympatric and synchronic populations of amphigonic organisms can almost unequivocally be identified as species when reproductive gaps occur between them. In such situations species are recognized by appropriate descriptors (characters) as genetic units and ecological units. Multivariate statistical methods provide a powerful tool to analyse more complex situations where non-amphigonic organisms and/or allopatric populations are investigated, on condition that appropriate character sets are considered. The increasing availability of molecular data for analysis certainly enhances the recognition of species as genetic unities, whilst much of the ecological role of an organism may be read from a careful choice of morphometric and ethological descriptors. On these premises it is suggested that species can be defined as groups of individuals (populations) which are discretely separated from other such groups in the character space. This definition is phenetical in its form but biological in its meaning since character sifting and weighting are considered essential features at the operational level
Contributi della Biologia molecolare alla sistematica entomologica, con particolare riferimento all’entomologia applicata. Introduzione.
No full textInsights 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
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
Figure 1 from: Todisco V, Nazari V, Cesaroni D, Sbordoni V (2017) Preliminary molecular phylogeny and biogeography of the monobasic subfamily Calinaginae (Lepidoptera, Nymphalidae). Zoosystematics and Evolution 93(2): 255-264. https://doi.org/10.3897/zse.93.10744
No full textFigure 1 -
(A) Approximate geographic distributions (Shirôzu 1960, Lang 2012) and sampling localities (circles) for the species of Calinaga included in this study (with the exception of the sample CBUD-INDIN for which we do not have an exact locality). Species as initially identified are highlighted and shown in different colours. Note that many of these initially attributed names subsequently proved erroneous. The map was obtained using Quantum GIS 2.8.2 based on a map from Natural Earth (www.naturalearthdata.com). (B) Median-Joining Network of mtDNA. Circle size proportional to haplotype frequency; number of nucleotide substitutions indicated along connections, except for single or double substitutions. In both figures the species are highlighted and shown in different colours as initially identified
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
Phosphoglucomutase polymorphism and natural selection in populations of cave cricket Dolichopoda geniculata.
No full textformerly Z. f. zool. Systematik u. Evolutionforschun
POPULATION GENETIC STRUCTURING IN ISOPODS: HISTORICAL AND ECOLOGICAL DETERMINANTS
No full textIsopods are crustaceans that show a wide adaptive radiation. They inhabit benthic marine and freshwater envi-ronments, are parasites of crustaceans and fishes, and have colonized terrestrial habitats. Isopods show an extraor¬dinary diversification in adaptations, coinciding with an equally diverse array of different degrees of stenoecy, char¬acterizing individual species. Among terrestrial isopods, trichoniscids show a very limited dispersal ability. This is mainly due to physiological constraints that necessitate them to inhabit humid edafic environments, and subterranean habitats. Results from genetic surveys have revealed that genetic variability in trichoniscids ranges in a wide spec¬trum, and a high degree of specific structure is often detectable (Gentile & Sbordoni, 1998; Gentile et al. 1998; Gentile & Allegrucci, submitted; Cobolli Sbordoni et al., 1997). Thus, trichoniscids are a valuable tool to study the inter- intrapopulation components of genetic variation, often allowing the researcher to detect the action of the different evolutionary factors as genetic drift, selection, and gene flow, separately. In this communication we discuss some case studies in which it has been possible to relate the genetic structure observed to historical and ecological factors.
Centile. C. & V. Sbordoni. 1998. Evolution 52: in press.
Gentile, G.. S. Sarbu, M. Menichetti 4 S. Galdenzi. 1998. In: H. Wilkens (ed.). Ecosystems of the World. In press.
Cobolli Sbordoni, M.. V. Ketmaier. E. De Matthaeis & S. Taiti. 1997. Heredity. 79: 463-472
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