243 research outputs found

    Un profilo storico dell'interrelazione fra leadership e comunicazione sociale

    Get PDF
    [ΔΔ ÎŽÎčÎ±Ï„ÎŻÎžÎ”Ï„Î±Îč Ï€Î”ÏÎŻÎ»Î·ÏˆÎ·][No abstract available

    Timeframe of speciation inferred from secondary contact zones in the European tree frog radiation (Hyla arborea group).

    Get PDF
    BACKGROUND: Hybridization between incipient species is expected to become progressively limited as their genetic divergence increases and reproductive isolation proceeds. Amphibian radiations and their secondary contact zones are useful models to infer the timeframes of speciation, but empirical data from natural systems remains extremely scarce. Here we follow this approach in the European radiation of tree frogs (Hyla arborea group). We investigated a natural hybrid zone between two lineages (Hyla arborea and Hyla orientalis) of Mio-Pliocene divergence (~5 My) for comparison with other hybrid systems from this group. RESULTS: We found concordant geographic distributions of nuclear and mitochondrial gene pools, and replicated narrow transitions (~30 km) across two independent transects, indicating an advanced state of reproductive isolation and potential local barriers to dispersal. This result parallels the situation between H. arborea and H. intermedia, which share the same amount of divergence with H. orientalis. In contrast, younger lineages show much stronger admixture at secondary contacts. CONCLUSIONS: Our findings corroborate the negative relationship between hybridizability and divergence time in European tree frogs, where 5 My are necessary to achieve almost complete reproductive isolation. Speciation seems to progress homogeneously in this radiation, and might thus be driven by gradual genome-wide changes rather than single speciation genes. However, the timescale differs greatly from that of other well-studied amphibians. General assumptions on the time necessary for speciation based on evidence from unrelated taxa may thus be unreliable. In contrast, comparative hybrid zone analyses within single radiations such as our case study are useful to appreciate the advance of speciation in space and time

    The Wall Lizards of the Balkan Peninsula: Tackling Questions at the Interphase of Phylogenomics and Population Genomics

    Get PDF
    [Abstract] Wall lizards of the genus Podarcis (Sauria, Lacertidae) are the predominant reptile group in southern Europe, including 24 recognized species. Mitochondrial DNA data have shown that, with the exception of P. muralis, the Podarcis species distributed in the Balkan peninsula form a species group that is further sub-divided into two subgroups: the one of “P. tauricus” consisting of P. tauricus, P. milensis, P. gaigeae, and P. melisellensis, and the other of “P. erhardii” comprising P. erhardii, P. levendis, P. cretensis, and P. peloponnesiacus. In an attempt to explore the Balkan Podarcis phylogenomic relationships, assess the levels of genetic structure and to re-evaluate the number of extant species, we employed phylogenomic and admixture approaches on ddRADseq (double digested Restriction site Associated DNA sequencing) genomic data. With this efficient Next Generation Sequencing approach, we were able to obtain a large number of genomic loci randomly distributed throughout the genome and use them to resolve the previously obscure phylogenetic relationships among the different Podarcis species distributed in the Balkans. The obtained phylogenomic relationships support the monophyly of both aforementioned subgroups and revealed several divergent lineages within each subgroup, stressing the need for taxonomic re-evaluation of Podarcis’ species in Balkans. The phylogenomic trees and the species delimitation analyses confirmed all recently recognized species (P. levendis, P. cretensis, and P. ionicus) and showed the presence of at least two more species, one in P. erhardii and the other in P. peloponnesiacus.This study was funded by NSFR 2007-2013 programme for development, European Social Fund, Operational Programme, Education and Lifelong Learning investing in knowledge society, Ministry of Education and Religious Affairs, Managing Authority, Co-financed by Greece and the European Union. Part of this work was funded by the Klaus Tschira Foundation, by the Ministry of Science and Innovation of Spain (PID2019-104184RB-I00 / AEI / 10.13039/501100011033), and by the Xunta de Galicia and FEDER funds of the EU under the Centro de Investigación de Galicia accreditation 2019-2022 (ED431G 2019/01)Xunta de Galicia; ED431G 2019/0

    Landscape connectivity limits the predicted impact of fungal pathogen invasion

    Get PDF
    Infectious diseases are major drivers of biodiversity loss. The risk of fungal diseases to the survival of threatened animals in nature is determined by a complex interplay between host, pathogen and environment. We here predict the risk of invasion of populations of threatened Mediterranean salamanders of the genus Lyciasalamandra by the pathogenic chytrid fungus Batrachochytrium salamandrivorans by combining field sampling and lab trials. In 494 samples across all seven species of Lyciasalamandra, B. salamandrivorans was found to be absent. Single exposure to a low (1000) number of fungal zoospores resulted in fast buildup of lethal infections in three L. helverseni. Thermal preference of the salamanders was well within the thermal envelope of the pathogen and body temperatures never exceeded the fungus' thermal critical maximum, limiting the salamanders' defense opportunities. The relatively low thermal host preference largely invalidates macroclimatic based habitat suitability predictions and, combined with current pathogen absence and high host densities, suggests a high probability of local salamander population declines upon invasion by B. salamandrivorans. However, the unfavorable landscape that shaped intraspecific host genetic diversity, lack of known alternative hosts and rapid host mortality after infection present barriers to further, natural pathogen dispersal between populations and thus species extinction. The risk of anthropogenic spread stresses the importance of biosecurity in amphibian habitats

    Endoparasites of european wildcats (Felis silvestris) in Greece

    Get PDF
    The European wildcat (Felis silvestris) is the only wild felid living in Greece. Wildcat populations are declining due to anthropogenic and phenological unfavourable conditions, and parasites may have an additional negative impact. In the present study, the occurrence of endoparasites in wildcats in Greece and the potential threats posed to wildcats, domestic animals, and humans in the study areas has been investigated. In a six-year period, 23 road-killed wildcats and 62 wildcat faecal samples were collected from different areas of the country. Necropsy for the detection of endopara-sites and standard parasitological examinations of faecal samples were performed. Parasites were morphologically identified and, in selected cases, molecularly analysed. All necropsied wildcats (100%) were infected by three to 10 different parasite taxa, with the most prevalent being Taenia taeniaeformis (73.9%), Toxocara cati (60.9%), Angiostrongylus chabaudi (56.5%), Ancylostoma tubaeforme (39.1%), Cylicospirura spp. (34.8%), Troglostrongylus brevior (34.8%), and Capillaria aerophila (33.8%). Of the 62 faecal samples examined, 53 (85.5%) were positive for one or more parasite elements (larvae, eggs, or oocysts). The most frequent were T. cati (45.2%), A. chabaudi (29%), C. aerophila (24.2%), and Ancylostomatidae (17.7%). This is the first survey on endoparasites affecting wildcats in Greece. Some of the parasites here found are frequent in domestic and wild felids, while others, i.e., Oslerus rostratus and Cylicospirura petrowi, were described for the first time in the European wildcat. Most of them have a significant pathogenic potential, causing severe to hazardous diseases to infected felids and some, under specific circumstances, can also threaten human health

    Whole‐genome SNP genotyping unveils ancestral and recent introgression in wild and domestic goats

    Get PDF
    After the domestication of goats around 10,000 years before the present (BP), humans transported goats far beyond the range of their wild ancestor, the bezoar goat. This brought domestic goats into contact with many wild goat species such as ibex and markhor, enabling introgression between domestic and wild goats. To investigate this, while shedding light on the taxonomic status of wild and domestic goats, we analysed genome-wide SNP data of 613 specimens from 14 taxonomic units, including Capra hircus, C. pyrenaica, C. ibex (from Switzerland, Austria, Germany and Slovenia), C. aegagrus aegagrus, C. a. cretica, C. h. dorcas, C. caucasica caucasica, C. c. severtzovi, C. c. cylindricornis, C. falconeri, C. sibirica sibirica, C. s. alaiana and C. nubiana, as well as Oreamnos americanus (mountain goat) as an outgroup. To trace gene flow between domestic and wild goats, we integrated genotype data of local goat breeds from the Alps as well as from countries such as Spain, Greece, TĂŒrkiye, Egypt, Sudan, Iran, Russia (Caucasus and Altai) and Pakistan. Our phylogenetic analyses displayed a clear separation between bezoar-type and ibex-type clades with wild goats from the Greek islands of Crete and Youra clustered within domestic goats, confirming their feral origin. Our analyses also revealed gene flow between the lineages of Caucasian tur and domestic goats that most likely occurred before or during early domestication. Within the clade of domestic goats, analyses inferred gene flow between African and Iberian goats. The detected events of introgression were consistent with previous reports and offered interesting insights into the historical relationships among domestic and wild goats.Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655Javna Agencija za Raziskovalno Dejavnost RS http://dx.doi.org/10.13039/501100004329Ministry of Science and Higher Education of the Russian Federation http://dx.doi.org/10.13039/501100012190Peer Reviewe

    Whole‐genome SNP genotyping unveils ancestral and recent introgression in wild and domestic goats

    Get PDF
    After the domestication of goats around 10,000 years before the present (BP), humans transported goats far beyond the range of their wild ancestor, the bezoar goat. This brought domestic goats into contact with many wild goat species such as ibex and markhor, enabling introgression between domestic and wild goats. To investigate this, while shedding light on the taxonomic status of wild and domestic goats, we analysed genome-wide SNP data of 613 specimens from 14 taxonomic units, including Capra hircus, C. pyrenaica, C. ibex (from Switzerland, Austria, Germany and Slovenia), C. aegagrus aegagrus, C. a. cretica, C. h. dorcas, C. caucasica caucasica, C. c. severtzovi, C. c. cylindricornis, C. falconeri, C. sibirica sibirica, C. s. alaiana and C. nubiana, as well as Oreamnos americanus (mountain goat) as an outgroup. To trace gene flow between domestic and wild goats, we integrated genotype data of local goat breeds from the Alps as well as from countries such as Spain, Greece, TĂŒrkiye, Egypt, Sudan, Iran, Russia (Caucasus and Altai) and Pakistan. Our phylogenetic analyses displayed a clear separation between bezoar-type and ibex-type clades with wild goats from the Greek islands of Crete and Youra clustered within domestic goats, confirming their feral origin. Our analyses also revealed gene flow between the lineages of Caucasian tur and domestic goats that most likely occurred before or during early domestication. Within the clade of domestic goats, analyses inferred gene flow between African and Iberian goats. The detected events of introgression were consistent with previous reports and offered interesting insights into the historical relationships among domestic and wild goats
    • 

    corecore