Valerio Sbordoni | University of Rome Tor Vergata (original) (raw)

Papers by Valerio Sbordoni

Tassini, A., Cesaroni, D., Forestiero, S., & Sbordoni, V. (2003). Geographic patterns, mi... more Tassini, A., Cesaroni, D., Forestiero, S., & Sbordoni, V. (2003). Geographic patterns, mimicry and allozyme polymorphisms in Zygaena ephialtes (Linnaeus, 1767) (Lepidoptera: Zygaenidae, Zygaeninae). In KA EFETOV, WG TREMEWAN, & GM TARMANN (a cura di), ...

Gli organismi troglobi, presenti soprattutto nelle grotte calcaree delle regioni temperate, hanno... more Gli organismi troglobi, presenti soprattutto nelle grotte calcaree delle regioni temperate, hanno tradizionalmente rappresentato il risultato di lunghi processi di adattamento all'ambiente ipogeo favoriti dall'isolamento, e di conseguenza considerati come relitti geografici e/o filogenetici, costretti nelle grotte dai cambiamenti climatici avvenuti soprattutto nel Pleistocene. Il successivo grande sviluppo delle ricerche biospeleologiche nelle regioni tropicali e nei "tubi di lava" , particolarmente diffusi negli arcipelaghi delle Hawaii e delle Canarie, nonche nelle grotte sostenute troficamente da solfobatteri ha notevolmente ampliato la nostra concezione dei processi adattativi nelle grotte. In primo luogo l'invasione delle grotte e comunque vista come un processo attivo, ovvero la colonizzazione di un habitat libero e disponibile. Inoltre, il confronto tra diverse tipologie di grotte ha evidenziato sia il ruolo selettivo delle risorse trofiche, sia l'esistenza di tassi evolutivi significativamente diversi. I fattori maggiormente responsabili per l'evoluzione della troglomorfia, l'insieme, cioe, delle caratteristiche morfologiche proprie dei troglobi, sono il flusso genico (ovvero quanto le popolazioni siano isolate fra loro e dai rispettivi antenati epigei), la dimensione della popolazione (ovvero quanto la deriva genetica possa giocare un ruolo importante) e la selezione naturale. L'equilibrio tra questi fattori determina l'intensita e ilo tasso evolutivo relativo al cambiamento troglomorfico. I diversi ruoli giocati da questi fattori possono essere evidenziati studiando l'evoluzione delle specie sotterranee da diversi punti di vista, ovvero a livello ecologico, fisiologico, etologico, morfologico e genetico. Questo ultimo approccio, notevolmente ostacolato in passato dalla lunga durata dei cicli riproduttivi nei cavernicoli, ha potuto, in seguito, svilupparsi tramite l'uso di marcatori genetici come gli allozimi, le sequenze di DNA e i loci microsatellite. Grazie a questi marcatori e allo sviluppo di strumenti analitici sempre piu sofisticati e ora possibile indagare piu a fondo i meccanismi sottostanti il processo di adattamento all'ambiente cavernicolo. Diversi sono, infatti, gli studi volti a studiare i processi microevolutivi attraverso la stima di parametri rilevanti come il livello di polimorfismo, il grado di strutturazione genetica, la dimensione effettiva delle popolazioni, etc. In questa comunicazione verra esaminata una serie di casi di studio che hanno come protagonista il processo di adattamento in diversi tipi di ambiente sotterraneo.

Subfamily Coliadinae, Tribe Rhodocerini, genera Gonepteryx and others, subfamily Dismorpiinae gen... more Subfamily Coliadinae, Tribe Rhodocerini, genera Gonepteryx and others, subfamily Dismorpiinae genus Leptidea

International Journal of Speleology, 1982

The absolute size, N, of a Dolichopoda geniculata population was estimated both by the 'Lincoln-P... more The absolute size, N, of a Dolichopoda geniculata population was estimated both by the 'Lincoln-Petersen index and the total count on sample plot methods in a natural cave in Centra'l Italy. 19 pairs of estimates, obtained over 2 years, exhibit a seasonal pabtern and a mean value of N~430. Differences between estimates obtained with the 2 methods are not significant (P > 0.8). These results, and data from the Uterature enable most of the major factors infuencing the two types of estimates to be identified .. Respective cases where methods may be preferably applied are suggested.

Proceedings of the National Academy of Sciences of the United States of America, Jan 13, 2009

Despite the attention given to them, the Galápagos have not yet finished offering evolutionary no... more Despite the attention given to them, the Galápagos have not yet finished offering evolutionary novelties. When Darwin visited the Galápagos, he observed both marine (Amblyrhynchus) and land (Conolophus) iguanas but did not encounter a rare pink blackstriped land iguana (herein referred to as ''rosada,'' meaning ''pink'' in Spanish), which, surprisingly, remained unseen until 1986. Here, we show that substantial genetic isolation exists between the rosada and syntopic yellow forms and that the rosada is basal to extant taxonomically recognized Galápagos land iguanas. The rosada, whose present distribution is a conundrum, is a relict lineage whose origin dates back to a period when at least some of the present-day islands had not yet formed. So far, this species is the only evidence of ancient diversification along the Galápagos land iguana lineage and documents one of the oldest events of divergence ever recorded in the Galápagos. Conservation efforts are needed to prevent this form, identified by us as a good species, from extinction. genetic isolation ͉ molecular phylogeny ͉ evolution ͉ islands ͉ lizards S ince Darwin's pioneering work in the archipelago, the Galápagos Islands have been a major scientific resource for evolutionary biologists. This archipelago, currently consisting of about a dozen volcanic islands and more than 100 associated islets, is located on the equator, about 1,000 kilometers west of the South-American coast (Fig. 1). Given their volcanic origin, the Galápagos Islands host unique flora and fauna that have evolved over millions of years in geographic isolation, generating a variety of endemic species with unique and varied ecological, morphological, and behavioral adaptations (1, 2). Land iguanas are among the most spectacular representative species of the Galápagos Islands. They once lived in many areas of the Galápagos archipelago (Fig. 1). Currently, many factors contribute to their threatened status (3), one of which may be incomplete taxonomy (4). Two species of Galápagos land iguanas are currently recognized: Conolophus pallidus and Conolophus subcristatus, with the former occurring only on Santa Fe, whereas C. subcristatus occurs on Fernandina,

International Journal of Speleology, Jun 1, 1994

A D. geniculata population inhabiting a natural cave at low altitude near seashore was followed d... more A D. geniculata population inhabiting a natural cave at low altitude near seashore was followed during two years. The population size, distribution in three age classes, spatial distribution, feeding habits were recorded. The life-cycle was found semivoltine, with overlaps between next choorts in each age class. A comparison to other Dolichopoda showed that the population of Valmarino cave is one of the best adapted to cave life, and this may be related with both historical and present geographical and ecological conditions of the cave.

Springer eBooks, 1994

... FAB 1270** 7 16.5 2 Dl laetitiae Alberese, GR Buca della Troia BDT 1500* 535 15.5 3 DI etnisc... more ... FAB 1270** 7 16.5 2 Dl laetitiae Alberese, GR Buca della Troia BDT 1500* 535 15.5 3 DI etnisca cave, Sempro-niano, GR Campese cave, GR CAM 4400** 40 16.5 2 D. aegilion Arco cave,Bellegra, BEG 1500* 420 11.5 2 Dg geiiiculala ... Studi ecologici nella grotta di Valmarino. ...

International Journal of Speleology, 1990

Allozyme variation at 32 gene loci was studied in cave dwelling shrimps of the genus Troglocaris ... more Allozyme variation at 32 gene loci was studied in cave dwelling shrimps of the genus Troglocaris (fam. Atyidae). Populations were collected from several caves and wells belonging to different drainage systems in the Karst areas of NE Italy. Results suggest the existence of two sympatric, genetically distinct, biological species (provisionally indicated as species A and B in the T. anophthalmus complex) in the samples collected at the Duino Well, Sagrado and Comarie caves (Nei's 1):=0.209).Samples from Gradisca and Aurisina are represented by only one (A)or the other (B) of the two species, respectively. Two remaining eastern populations from the Rosandra Valley also proved to be monospecific. However, they possess fixed alternative alleles markedly different from both species A and B suggesting that these two populations may belong to a third sibling species, C (A vs C, 0=0.346; B vs C."15'=0.146).These data are discussed in relation to allopatric speciation of cave dwelling shrimp species, flooding periods of subterranean waters and the role of cave organisms as markers of this process.

Ecological Entomology, Feb 1, 1979

Population size as well as the absolute and relative frequencies of the phegea and filipendulae m... more Population size as well as the absolute and relative frequencies of the phegea and filipendulae mimetic complexes have been estimated in an area of Central Italy selected because it is: (a) little affected by man, (b) representative of many others in the Central Appennines, and (c) containing an abundant population of Zyguena ephialtes. 2. This distasteful polymorphic species belongs, in Central Italy as in other Southern areas, to the phegea complex (Zyguena ephialtes, yellow ephialtoid form), while in Northern and Central Europe it belongs to the filipendulue complex (Z.ephialtes, red peucedanoid form). 3. In the Southern areas the phegea complex is much more abundant than the filipendulue one, which gives the yellow ephialtoid form of Z.ephialtes a strong mimetic advantage over the red peucedanoid. 4. In addition, Arnutrr phegea greatly outnumbers the other distasteful members of its complex and emerges first. 5. Throughout its flight period Z.ephialtes, which emerges about 20 days later than A.phegea, never attains a frequency higher than 0.03 in this complex. It is suggested that in such a situation the protection that this species gains as a mimic would be very high regardless of its unpalatability. 6. These findings and others discussed in the present paper, such as the degree of unpalatability, the genetics of the mimetic form as well as the polymorphism for colour and pattern, are examined according to the hypothesis of divergent evolutionary strategies in Batesian and Miillerian mimicry. It is suggested that these are meaningful concepts but that individual mimics, of which Zephialtes is one, can fall between them. This paper has attracted serious criticism from some geneticists and ecologists (see Benson,

L’oggetto di questo contributo e una breve rassegna dei casi di studio presentati da uno di noi (... more L’oggetto di questo contributo e una breve rassegna dei casi di studio presentati da uno di noi (V.S.) durante la conferenza introduttiva alla Tavola Rotonda sul tema “Contributi della biologia molecolare alla sistematica entomologica con particolare riferimento all’Entomologia applicata”. Tra le ricerche sviluppate recentemente nel nostro laboratorio, sono state scelti quattro temi riguardanti problematiche di base, mentre nei successivi contributi alla Tavola Rotonda sara privilegiato l’aspetto applicativo. I quattro temi, gia oggetto parziale o totale di pubblicazione, riguardano la filogenesi e filogeografia delle Dolichopoda, la stima dei tassi evolutivi nei coleotteri batiscini, la ricostruzione filogeografia della colonizzazione nelle Hipparchia delle isole Azzorre, ed infine, un approccio molecolare alla variazione geografica del polimorfismo cromatico in Zygaena ephialtes.

Molecular Biology and Evolution, Jan 13, 2009

Biology and Evolution (GBE) prospective editors William Martin and Takashi Gojobori, Oxford Unive... more Biology and Evolution (GBE) prospective editors William Martin and Takashi Gojobori, Oxford University Press (OUP) representative Cathy Kennedy attended part of the meeting. The meeting began with Introductions. 2. Approval of minutes. À Council unanimously approved the minutes of the 2007 Council and Business meetings, published in the December 2007 issue of MBE and also available at http://www.smbe.org/archive.htm online. 3. Editor's report. À The MBE Editor gave a report on the health of the journal (see detailed Editor's report). 4. Treasurer's report. À Treasurer Marta Wayne summarized the financial state of the Society. Records indicate that the Society is in excellent financial health. (See detailed Treasurer's report). 5. Secretary's report. À Secretary Jianzhi Zhang reviewed Council actions over the preceding year. These notes, along with the meeting minutes, are summarized here: Election of SMBE Officers: Past-President Deborah Charlesworth appointed a Nominations Committee to select candidates for the offices of President-Elect, Councillor, and Treasurer. Members of the nominations committee included Pekka Pamilo (Chair), Jennifer Wernegreen, Cedric Feschotte, Nora Besansky, Yoshio Tateno, and Jianzhi Zhang (ex officio). Secretary Jianzhi Zhang informed society members of the composition of the committee and invited suggestions for nominees. The candidates standing for the elections were Jody Hey

... Autori: Deodati, T; Allegrucci, G; Cesaroni, D; Sbordoni, V. ... questo studio, che segue alc... more ... Autori: Deodati, T; Allegrucci, G; Cesaroni, D; Sbordoni, V. ... questo studio, che segue alcune indagini preliminari basate su sequenze del gene mitocondriale COI, abbiamo focalizzato l'attenzione su un gruppo di generi (Callerebia, Argestina, Loxerebia, Hemadara ed Eugrumia). ...

INTRODUZIONE La riduzione e lo shift degli areali di distribuzione, osservati per moltissime spec... more INTRODUZIONE La riduzione e lo shift degli areali di distribuzione, osservati per moltissime specie negli ultimi decenni, sono verosimilmente imputabili in gran parte al cambiamento climatico in atto (Parmesan 2006). Le farfalle rappresentano uno tra i migliori indicatori del cambiamento climatico: hanno, infatti, un ciclo vitale breve ed esigenze ecologiche relativamente ristrette. Obiettivo del presente lavoro è stata la realizzazione di modelli predittivi delle modificazioni future dell'areale potenziale in sei specie di Ropaloceri (tutte le specie, presenti in Italia centrale, inserite negli allegati II e IV della Direttiva 92/43/CEE: Maculinea arion, Melanargia arge, Euphydryas provincialis, Parnassius apollo, P. mnemosyne, Zerynthia cassandra). Si è inoltre valutata la capacità di tutela delle specie in esame da parte delle aree protette presenti in Italia centrale.

Journal of Biogeography, Apr 29, 2016

Aim Niche stability areas (NSAs) are portions of the species range where climate conditions remai... more Aim Niche stability areas (NSAs) are portions of the species range where climate conditions remain suitable through time. They represent the core of species ranges. Their distribution and extent, coupled with dispersal and colonization, shape the realized range of species. In this study, we quantified the roles of survival within NSAs and post-glacial dispersal in determining the current distribution of two groups of alpine butterflies (two taxa in the Erebia tyndarus species complex; three taxa in the Parnassius apollo-P. phoebus species complex). Location Holarctic. Methods NSAs were identified for each taxon by combining current and past potential distributions models, estimated using different modelling techniques and general circulation models. We then (1) assessed the distributional bias towards NSAs by comparing actual occurrence records with randomized occupancies of the current potential range and (2) quantified post-glacial dispersal by examining the distribution of distances from each occurrence record to the nearest NSA. Results In almost all taxa, realized distributions are biased towards NSAs. However, while Erebia's present range is strongly dominated by NSAs, some populations of Parnassius are found very far from NSAs, suggesting more effective colonization of the available geographical space. Main conclusions Our study highlights the relative roles of survival within NSAs and post-glacial dispersal in shaping the ranges of different alpine butterflies during the Holocene. Results suggest that Erebia was unable to disperse far from NSAs, thus experiencing increasing range fragmentation. Parnassius populations, on the other hand, coupled local survival with northward dispersal. As NSAs allowed the long-term survival of the species, acting as sources for recolonization, and tend to preserve most of each species' genetic diversity, identifying NSAs and understanding their importance in determining the current distribution of species represents a pivotal task for the conservation of biological diversity.