1,720,965 research outputs found
Phylogeography of Italian endemic Flea Beetles (Chrysomelidae, Galerucinae, Alticini): biogeographic, systematic, and conservation implications
Full text linkbiodiversity hotspot within the Mediterranean global biodiversity hotspot. However, most of the knowledge we have on phylogeographic patterns of Italian endemic species come from studies that have used vertebrates as model species, although they represent only a small part of the global biodiversity of the species (<1.5%). This makes our appraisal of the ecological response of species to past climatic changes far from complete.
In my PhD project, I used the highly diverse group of flea beetles endemic of the central Apennines (Coleoptera Chrysomelidae, Galerucinae, Alticini), to investigate the ecological, evolutionary and biogeographic processes primed by Quaternary glaciations cycles on temperate and high-altitude biota. These insects show distribution patterns from micro to macro scale, being present in most mountain ecosystems, and have restrictive and well-known ecological requirements, thus making them ideal phylogeographic models. The main aim of the thesis project is to study the historical processes that have shaped current patterns of genetic diversity within different endemic Alticni species of Apennines and to compare how species with different ecological requirements have responded to Quaternary climate change. To achieve these main aim, I have adopted a multi-taxa approach including (i) an integrative taxonomic approach to delimit the phylogenetic and taxonomic units, and (ii) a multilocus phylogeographic approach to identify the main Pleistocene refugia within the Apennine system, and to infer demographic and biogeographic processes underlying the formation of the observed intraspecific diversity patterns. Six target species were selected based on their distribution and ecology: Longitarsus springeri, Psylliodes biondii and Psylliodes springeri linked to high mountain environments; Longitarsus laureolae and Longitarsus zangherii linked to temperate environments and Psylliodes ruffoi linked to xerophilous environments. Three large sampling campaigns were performed to sample the populations of target species.
A first integrative morphological and molecular delimitation of the target species was done as a fundamental and preliminary step to the phylogeographic study. In this framework, three main issues related to the mismatch between molecular and morphological identification were pointed out and resolved. First, within the genus Longitarsus, we observed several instances of species misidentification and taxonomic incongruences within the public databases of DNA sequences (GenBank and BOLD). This makes difficult to implement a molecular identification of species by comparing the DNA sequence of a target gene (cox1) of a sampled individual with deposited sequences in public database through a DNA barcoding approach. To overcome this drawback, we implemented a methodical pipeline with a posteriori taxonomic revision that allow improving the quality of the reference-sequence library (from GenBank and BOLD) and the effectiveness of the DNA barcoding tool. Second, we observed that some samples, morphological identified as P. ruffoi, had molecular characters (i.e. DNA sequences) typical of the related species P. kiesenwetteri. The use of an integrative taxonomy approach within a phylogeographic framework allowed to delimit the two species P. ruffoi and P. kiesenwetteri from a molecular and morphological point of view, clarifying their phylogenetic and taxonomic relationship. Third, following the molecular assessment of the Maiella population of P. biondii, we observed that this population show a remarkable genetic distance relative to other populations of P. biondii, suggesting they are possibly two distinct species. Thanks to an integrative taxonomy approach, we were able to solve these taxonomic and systematic problems, to identify a new lineage (possibly a new species) endemic to the Maiella mountains, and thus to identify the evolutionary units on which to deepen the phylogeographical study. [...
Past and current climate as a driver in shaping the distribution of the Longitarsus candidulus species group (Coleoptera: Chrysomelidae)
Full text linkLongitarsus candidulus (Foudras) is a thermophilic flea beetle species widely distributed in the Mediterranean Basin and associated with Daphne gnidium L. and Thymelaea hirsuta (L.). Longitarsus laureolae Biondi and Longitarsus leonardii Doguet, phylogenetically closely related to L. candidulus, show together a peculiar and rare disjunct distribution along the central-southern Apennines and the Cantabrian-Pyrenean mountain system, respectively. Both are associated with Daphne laureola L. in mesophilic habitats. We used "ecological niche modeling" to infer the Pleistocene dynamics in the distribution of the three flea beetle species and their host plants. We interpreted their current distributions, paying particular attention to the presumed time of species divergence as inferred from recent studies. The differentiation of L. laureolae and L. leonardii from L. candidulus likely represents a response to the marked climatic changes during the Late Pliocene. Such a split was likely associated with a trophic niche shift of the laureolae/leonardii ancestor towards the typically mesophilic host plant D. laureola. The subsequent split between L. laureolae and L. leonardii, possibly due at first to the niche competition, was then boosted by an allopatric divergence during the Middle Pleistocene, likely caused by a large area of low environmental suitability for both species, mainly located between the northern Apennines and the south-western Alps
Identification of Dipteran species inhabiting Tuber aestivum (the summer truffle) ascomata
No full textTuber spp. (Ascomycota) forms hypogeous fruiting bodies (truffles) that host many microbial species as well as invertebrates which feed on them. Despite the larvae and adults of Diptera and Coleoptera are commonly found to inhabit truffles, molecular investigations assessing their occurrence are still few and the number of species is probably underestimated. In this study, 52 larvae and adults of Diptera from 23 T. aestivum ascomata collected in two provinces of northern and central Italy were molecularly characterized. The sequences fell into four Diptera families, and four taxa were identified as Cheilosia soror, Phaonia cf. trimaculata, Drosophila subobscura, and Suillia gigantea. Morphology of adults belonging to these species confirmed their identity. Additional three taxa belonging to the Helomyzidae remained unclassified. The study highlighted the coexistence of different Diptera species in the same ascoma, suggesting potential lack of competitive exclusion. Geographical distribution analysis reveals non-site specificity for most species. This research contributes insights into the diversity of Dipteran species and their interactions with truffles and lays the groundwork for their monitoring, at a time where truffle resources are threatened by anthropic and environmental factors
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
Genetic Diversity and Distribution of Italian Cave Crickets (<i>Dolichopoda</i>): Toward a Better Understanding of Lineage Structure
Full text linkCave crickets of the genus Dolichopoda (Orthoptera; Rhaphidophoridae) represent a key component of cave ecosystems. In Italy, nine species are currently known, distributed from the northwestern regions to the southernmost Apennines, with occurrences also along various Tyrrhenian coastal areas and islands, including Sardinia. In this study, we focus on the Apennine region, where we sampled 18 populations of Dolichopoda spp. and sequenced mitochondrial markers (cox1 and 16S) from newly collected individuals to investigate their distribution and genetic diversity. Our analyses identified two previously unrecognized lineages within D. geniculata. Moreover, the sampled caves in the northern Apennines allowed us to refine the distributional ranges of D. geniculata, D. letitiae, and D. schiavazzii. Finally, we provide comments to support a future taxonomic revision of the group
Corrigendum: Salvi D, Al-Kandari M, Oliver PG, Berrilli E, Garzia M (2022) Cryptic marine diversity in the northern Arabian Gulf: an integrative approach uncovers a new species of oyster (Bivalvia: Ostreidae), Ostrea oleomargarita. Journal of Zoological Systematics and Evolutionary Research 2022: 7058975. https://doi.org/10.1155/2022/7058975
Full text linkHere we provide a Code-compliant description of Ostrea oleomargarita Oliver, Salvi, and Al-Kandari, sp. nov as reported in Salvi et al. (2022) and complemented with the ZooBank registration numbers of the publication and of the new species name. Results of phylogenetic, species delimitation, and morphological analyses on which the systematic assessment of this new species is based can be found in Salvi et al. (2022)
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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