Donatella Cesaroni

Patterns of evolution and multidimensional systematics in graylings (Lepidoptera: Hipparchia)

The difficult and controversial attribution of Hipparchia (Parahipparchia) populations to species or subspecies rank led us to use a comparative, quantitative approach to clarify evolutionary and taxonomic relationships among taxa. Seventeen populations from the Mediterranean area belonging to nine presumptive species or subspecies were sampled, and multivariate analyses were employed to study three character sets: allozymes, morphometric profiles of male genitalia, and quantitative descriptors of wing pattern and shape. Comparative analyses of distance matrices, trees and ordination patterns enabled us to outline evolutionary relationships among taxa and to assess the relative value of each character set. Congruent relationships among taxa were obtained from allozymes and male genital morphometrics, suggesting that divergence in genital morphology is a fairly good marker of the overall genetic divergence. On the other hand, discordant results from wing pattern descriptors suggest these might be subjected to different evolutionary trajectories and rates because of their particular adaptive significance, and might not represent reliable tracers of phylogeny.

Plant sciences and the Italian National Biodiversity Network

Abstract Several national and global initiatives aim to increase access to biodiversity information worldwide. The Italian National Biodiversity Network, started in the framework of the project “Sistema Ambiente 2010”, will organise and manage biodiversity data hosted by museums, universities and research centres in Italy, in order to make them widely available on the Web.

Genetic structure of populations and species of Dolichopoda cave crickets: evidence of peripatric divergence

Abstract Twenty-five populations of Dolichopoda cave crickets from Central-Southern Italy have been surveyed for allozyme variation at the products of 15 structural gene loci. The samples, as characterized on morphological bases, included six local populations of D. schiavazzii, one of D. aegilion, three of D. baccettii, six of D. laetitiae and nine of D. geniculata. The genetic distances between conspecific populations range from 0.014 to 0.240, those between species range from 0.054 to 0.501. The analysis of the cladogram, derived from D values, does not show a clear-cut situation within the laetitiae-geniculata group. Multivariate analyses of allele frequency data (PCA and TRGRPS) suggest that geography rather than morphology is the main factor explaining the distribution of the laetitiae-geniculata populations on the scatter diagrams. Peripheral cave populations adjacent to the Tyrrhenian and Adriatic coasts show high degrees of genetic differentiation from each other and from the inland cave populati...

Evolutionary divergence in Dolichopoda cave crickets: A comparison of single copy DNA hybridization data with allozymes and morphometric distances

In this paper we attempt to investigate relationships between the amount of genetic divergence in nuclear genes and the degree of morphological differentiation for different sets of characters in Dolichopoda cave crickets.

A narrow hybrid zone between two crayfish species from a Mexican cave

In Northern Chiapas (Mexico), two newly discovered species of Procambarus crayfish inhabit a subterranean stream. These species can be morphologically distinguished only by comparing extreme phenotypes (dark, thick‐eyed, surface dwelling‐like individuals vs light, elongated, microphtalmic, cave dwelling‐like individuals). Individuals with intermediate phenotypes co‐occur with those exhibiting extreme phenotypes.

Testing Classical Species Properties with Contemporary Data: how 'Bad Species' in the Brassy Ringlets (Erebia tyndarus complex, Lepidoptera) Turned Good.

All species concepts are rooted in reproductive, and ultimately genealogical, relations. Genetic data are thus the most important source of information for species delimitation. Current ease of access to genomic data and recent computational advances are blooming a plethora of coalescent-based species delimitation methods. Despite their utility as objective approaches to identify species boundaries, coalescent-based methods (1) rely on simplified demographic models that may fail to capture some attributes of biological species, (2) do not make explicit use of the geographic information contained in the data, and (3) are often computationally intensive. In this article, we present a case of species delimitation in the Erebia tyndarus species complex, a taxon regarded as a classic example of problematic taxonomic resolution. Our approach to species delimitation used genomic data to test predictions rooted in the biological species concept and in the criterion of coexistence in sympatry. We (1) obtained restriction-site associated DNA (RAD) sequencing data from a carefully designed sample, (2) applied two genotype clustering algorithms to identify genetic clusters, and (3) performed within-clusters and between-clusters analyses of isolation by distance as a test for intrinsic reproductive barriers. Comparison of our results with those from a Bayes factor delimitation coalescent-based analysis, showed that coalescent-based approaches may lead to overconfident splitting of allopatric populations, and indicated that incorrect species delimitation is likely to be inferred when an incomplete geographic sample is analyzed. While we acknowledge the theoretical justification and practical usefulness of coalescent-based species delimitation methods, our results stress that, even in the phylogenomic era, the toolkit for species delimitation should not dismiss more traditional, biologically grounded, approaches coupling genomic data with geographic information.

Cloning and characterization of the European seabass, Dicentrarchus labrax, mitochondrial genome

Mitochondrial DNA (mtDNA) from the European seabass, Dicentrarchus labrax, has been cloned and characterized. Its gene organization was deduced by a comparison of the sequenced termini of different subclones obtained from European seabass mtDNA to the completely-sequenced mtDNAs from carp and freshwater loach. The difference in genome size between the European seabass mtDNA (approximately 18 kb) and most of the other characterized fish mtDNAs (approximately 16.5 kb) is accounted for by the displacement-loop (D-loop). Comparisons have been performed between the derived amino-acid sequences of three sequenced genes, cytochrome c oxidase subunit 2 (COII), NADH dehydrogenase subunit 4L (ND4L) and ATP synthase subunit 8 (ATPase8), from D. labrax, and their counterparts in other fishes and Xenopus laevis.

Evolutionary genetics and morphometrics of a cave crayfish population from Chiapas (Mexico)

The recently explored Cueva de Los Camarones, in the remote village of Constitucion, Chiapas, Mexico, houses a unique highly variable population of Procambarus crayfish (Crustacea, Decapoda). Morphologically, a more or less dinal variation is revealed at several features such as the degree of rudimentation in both pigmentation and eye, and the elongation of body and appendages. Extremes are quite different, ranging from typical dark, thick, eyed individuals to light, elongated, microphtalmic phenotypes. Evolutionary relationships among individuals were investigated electrophoretically (25 structural gene loci) and morphometrically (12 characters) by means of multivariate analyses. Results from analysis of individual allozymic multilocus profiles indicate that the «light» phenotypes belong to a distinct gene pool with respect to the «dark» ones, but some level of introgression is hypothesized. Results from analysis of individual morphometric profiles also show a discrimination between «light» and « dark» samples, chiefly determined by the shape of the rostrum and chela. The existence of such a discontinuous variation both in morphometric and allozymic characters presumably reflects a history of allopatric divergence followed by secondary contact of the two species.

Length variation in mtDNA control region in hatchery stocks of European sea bass subjected to acclimation experiments

Length polymorphism of the mtDNA control region was analysed in samples from the sea bass Dicentrarchus labrax before and after acclimation to freshwater. Acclimation trials were repeated twice for two samples originating from the same broodstock. DNA amplification of 221 individuals made it possible to detect 40 different D-loop length variants and a mean level of gene diversity (/c!) of 0.850. Out of 52 scored distinct genotypes, 18 were homoplasmic and the remaining ones were heteroplasmic for up to four variants. Shifts in frequencies between starting and acclimated samples in the same direction of the same genotypes in both years were not observed. Patterns of mtDNA control region variation were compared to previous allozymic and RAPD studies carried out on the same samples. While variation found in the allozyme alleles and the RAPD markers in replicate experiments revealed differential survival of the genotypes, stochastic processes, such as genetic drift, explained the observed variation of mtDNA control region. Very high levels of genotype diversity were observed within each sample, ranging from 0.77 to 0.97. This high diversity associated with the maternal inheritance of mtDNA makes this molecular marker especially suitable for studies in aquaculture genetics, when the allozyme studies fail to reveal genetic variation or when the identification of progeny based on the mothers contribution is relevant.

Multivariate analysis of multi‐character individual profiles as a tool in systematics

Abstract The 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 e...