167 research outputs found

    A New Species of \u3cem\u3eCallulina\u3c/em\u3e (Anura: Microhylidae) from the West Usambara Mountains, Tanzania

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    The description of the species Callulina kreffti was based on specimens collected in the East Usambara Mountains of Tanzania. Successive collecting has shown this species to be widely distributed through the Eastern Arc Mountains. Advertisement calls from populations in the type locality of Callulina kreffti were compared with calls from populations in the West Usambara Mountains. Analysis of the calls suggested that these two populations of Callulina represent two separate taxa. Subsequent morphological and molecular investigations indicated that these two populations are distinct. Herein, we describe a new Callulina species on the basis of call, morphology and molecular sequences

    Toad radiation reveals into-India dispersal as a source of endemism in the Western Ghats-Sri Lanka biodiversity hotspot

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    <p>Abstract</p> <p>Background</p> <p>High taxonomic level endemism in the Western Ghats-Sri Lanka biodiversity hotspot has been typically attributed to the subcontinent's geological history of long-term isolation. Subsequent out of – and into India dispersal of species after accretion to the Eurasian mainland is therefore often seen as a biogeographic factor that 'diluted' the composition of previously isolated Indian biota. However, few molecular studies have focussed on into-India dispersal as a possible source of endemism on the subcontinent. Using c. 6000 base pairs of mitochondrial and nuclear DNA, we investigated the evolutionary history and biogeography of true toads (Bufonidae), a group that colonized the Indian Subcontinent after the Indo-Asia collision.</p> <p>Results</p> <p>Contrary to previous studies, Old World toads were recovered as a nested clade within New World Bufonidae, indicating a single colonization event. Species currently classified as <it>Ansonia </it>and <it>Pedostibes </it>were both recovered as being non-monophyletic, providing evidence for the independent origin of torrential and arboreal ecomorphs on the Indian subcontinent and in South-East Asia. Our analyses also revealed a previously unrecognized adaptive radiation of toads containing a variety of larval and adult ecomorphs. Molecular dating estimates and biogeographic analyses indicate that the early diversification of this clade happened in the Western Ghats and Sri Lanka during the Late Oligocene to Early Miocene.</p> <p>Conclusion</p> <p>Paleoclimate reconstructions have shown that the Early Neogene of India was marked by major environmental changes, with the transition from a zonal- to the current monsoon-dominated climate. After arrival in the Western Ghats-Sri Lanka hotspot, toads diversified <it>in situ</it>, with only one lineage able to successfully disperse out of these mountains. Consequently, higher taxonomic level endemism on the Indian Subcontinent is not only the result of Cretaceous isolation, but also of invasion, isolation and radiation of new elements after accretion to the Eurasian mainland.</p

    Species boundaries and biogeography of East African torrent frogs of the genus Petropedetes (Amphibia: Anura: Petropeditidae)

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    Based on morphology there are currently three described East African species of torrent frogs belonging to the tropical African genus Petropedetes (P. dutoiti, P. martiennseni and P. yakusini). Taxonomic uncertainties are evident within this group: a putative new species reported from the Nguru Mountains and the species P. yakusini have a fragmented distribution across the Southern Tanzanian highlands. We conducted a molecular systematic study, sampling populations of East African petropedetids occurring in the mountains of Tanzania (P. martiennseni and P. yakusini), to investigate species boundaries and biogeography. Data provide evidence for the recognition of well-defined genetically distinct populations occurring in each mountain fragment (for P. yakusini), and further support for a new undescribed species from the Nguru Mountains. We examine phylogenetic patterns in relation to the biogeographic history of the region

    ZADOVOLJSTVO POSLOM ZAPOSLENIKA U HOTELSKOJ INDUSTRIJI HRVATSKE

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    Mjerenje zadovoljstva zaposlenika poslom pomaže managerima u donošenju na informacijama baziranih odluka u području upravljanja ljudskim potencijalima, ali i poduzeća sveukupno. Mjerenje osim toga doprinosi razumijevanju načina na koji se zadovoljstvo poslom uklapa u sveukupnu sliku motivacije za rad i rezultata rada. U ovom su radu prezentirani rezultati istraživanja zadovoljstva zaposlenika poslom u hrvatskoj hotelskoj industriji

    Exploration into the hidden world of Mozambique’s sky island forests:new discoveries of reptiles and amphibians

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    We carried out a survey of reptiles and amphibians within Afromontane forest and woodland slopes of three inselbergs in northern Mozambique (Mount Mabu, Mount Namuli, and Mount Ribáuè). A total of 56 species (22 amphibians and 34 reptiles) were recorded during the current survey. Our findings substantially increase the number of herpetofaunal species recorded from these mountains (Mount Ribáuè 59%, Mount Mabu 37%, and Mount Namuli 11% of the total species), including one new country record and several putative new species. An updated checklist of the herpetofauna of these mountains is presented

    Phylogenetic relationships of African microhylid frogs inferred from DNA sequences of mitochondrial 12S and 16S rRNA genes

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    The phylogenetic relationships of microhylid frogs are poorly understood. The first molecular phylogeny for continental African microhylids is presented, including representatives of all subfamilies, six of the eight genera, and the enigmatic hemisotid Hemisus. Mitochondrial 12S and 16S rRNA sequence data were analysed using parsimony, likelihood and Bayesian methods. Analyses of the data are consistent with the monophyly of all sampled subfamilies and genera. Hemisus does not nest within either brevicipitines or non-brevicipitines. It is possibly the sister group to brevicipitines, in which case brevicipitines might not be microhylids. Phrynomantis and Hoplophryne potentially group with non-African, non-brevicipitine microhylids, in agreement with recent morphological and molecular data. Within brevicipitines, Breviceps is recovered as the sister group to a clade of Callulina+Spelaeophryne+Probreviceps. The relationships among the genera within this latter clade are unclear, being sensitive to the method of analysis. Optimal trees suggest the Probreviceps macrodactylus subspecies complex might be paraphyletic with respect to P. uluguruensis, corroborating preliminary morphological studies indicating that P. m. rungwensis may be a distinct species. P. m. loveridgei may be paraphyletic with respect to P. m. macrodactylus, though this is not strongly supported. Some biogeographic hypotheses are examined in light of these findings

    No ecological opportunity signal on a continental scale?:Diversification and life-history evolution of african true toads (Anura: Bufonidae)

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    The niche-filling process predicted by the “ecological opportunity” (EO) model is an often-invoked mechanism for generating exceptional diversity in island colonizers. Whether the same process governs lineage accumulation and trait disparity during continental colonization events is less clear. Here, we test this prediction by investigating the rate dynamics and trait evolution of one of Africa's most widespread amphibian colonizers, the true toads (Bufonidae). By reconstructing the most complete molecular phylogeny of African Bufonidae to date, we find that the diversification of lineages in Africa best conforms to a constant rate model throughout time and across subclades, with little support for EO. Evolutionary rates of life-history traits have similarly been constant over time. However, an analysis of generalists and specialists showed a shift toward higher speciation rates associated with habitat specialization. The overall lack of EO signal can be interpreted in a number of ways and we propose several explanations. Firstly, methodological issues might preclude the detection of EO. Secondly, colonizers might not experience true EO conditions and due to the size, ecological heterogeneity and age of landmasses, the diversification processes might be more complex. Thirdly, lower speciation rates of habitat generalists may have affected overall proliferation of lineages

    High Prevalence of the Amphibian Chytrid Fungus (\u3cem\u3eBatrachochytrium dendrobatidis\u3c/em\u3e) across Multiple Taxa and Localities in the Highlands of Ethiopia

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    Surveys of the potentially lethal amphibian chytrid fungus (Batrachochytrium dendrobatidis - Bd) in Africa are patchy, especially in some regions of high species endemicity. We present results of the first Bd surveys of wild amphibians in Ethiopia, for two upland regions on either side of the Rift Valley: the Bale Mountains and the Kaffa region. Surveys were opportunistic so that robust interpretation of the data is limited. Utilizing diagnostic qPCR assays, 51 out of 120 frogs (14 species in 10 genera) tested positive for Bd at altitudes of 1,620–3,225 m, across all genera and species, and all but two localities. Prevalence was not significantly different between the two regions or two years (2008, 2009) sampled. Prevalence and parasite load was higher in species with aquatic tadpoles than those with terrestrial early life-history stages, but these differences were not significant. Impacts of Bd infection were not investigated, but no dead or dying frogs were found. This is the first report of Bd in Ethiopia, a country in which approximately 40% of its more than 60 species are endemic. Declines have occurred in some frog species in some localities in Ethiopia, and although habitat degradation is a likely cause in at least some places, further studies of Bd in Ethiopia are required to understand if it is a threat

    Evolutionary Relationships of the Critically Endangered Frog \u3cem\u3eEricabatrachus baleensis\u3c/em\u3e Largen, 1991 with Notes on Incorporating Previously Unsampled Taxa into Large-scale Phylogenetic Analyses

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    Background: The phylogenetic relationships of many taxa remain poorly known because of a lack of appropriate data and/or analyses. Despite substantial recent advances, amphibian phylogeny remains poorly resolved in many instances. The phylogenetic relationships of the Ethiopian endemic monotypic genus Ericabatrachus has been addressed thus far only with phenotypic data and remains contentious. Results: We obtained fresh samples of the now rare and Critically Endangered Ericabatrachus baleensis and generated DNA sequences for two mitochondrial and four nuclear genes. Analyses of these new data using de novo and constrained-tree phylogenetic reconstructions strongly support a close relationship between Ericabatrachus and Petropedetes, and allow us to reject previously proposed alternative hypotheses of a close relationship with cacosternines or Phrynobatrachus. Conclusions: We discuss the implications of our results for the taxonomy, biogeography and conservation of E. baleensis, and suggest a two-tiered approach to the inclusion and analyses of new data in order to assess the phylogenetic relationships of previously unsampled taxa. Such approaches will be important in the future given the increasing availability of relevant mega-alignments and potential framework phylogenies

    Differential expression analysis for sequence count data

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    *Motivation:* High-throughput nucleotide sequencing provides quantitative readouts in assays for RNA expression (RNA-Seq), protein-DNA binding (ChIP-Seq) or cell counting (barcode sequencing). Statistical inference of differential signal in such data requires estimation of their variability throughout the dynamic range. When the number of replicates is small, error modelling is needed to achieve statistical power.&#xd;&#xa;&#xd;&#xa;*Results:* We propose an error model that uses the negative binomial distribution, with variance and mean linked by local regression, to model the null distribution of the count data. The method controls type-I error and provides good detection power. &#xd;&#xa;&#xd;&#xa;*Availability:* A free open-source R software package, _DESeq_, is available from the Bioconductor project and from &#x22;http://www-huber.embl.de/users/anders/DESeq&#x22;:http://www-huber.embl.de/users/anders/DESeq
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