563 research outputs found

    Shotgun Mitogenomics Provides a Reference Phylogenetic Framework and Timescale for Living Xenarthrans

    Get PDF
    Xenarthra (armadillos, sloths, and anteaters) constitutes one of the four major clades of placental mammals. Despite their phylogenetic distinctiveness in mammals, a reference phylogeny is still lacking for the 31 described species. Here we used Illumina shotgun sequencing to assemble 33 new complete mitochondrial genomes, establishing Xenarthra as the first major placental clade to be fully sequenced at the species level for mitogenomes. The resulting data set allowed the reconstruction of a robust phylogenetic framework and timescale that are consistent with previous studies conducted at the genus level using nuclear genes. Incorporating the full species diversity of extant xenarthrans points to a number of inconsistencies in xenarthran systematics and species definition. We propose to split armadillos in two distinct families Dasypodidae (dasypodines) and Chlamyphoridae (euphractines, chlamyphorines, and tolypeutines) to better reflect their ancient divergence, estimated around 42 million years ago. Species delimitation within long-nosed armadillos (genus Dasypus) appeared more complex than anticipated, with the discovery of a divergent lineage in French Guiana. Diversification analyses showed Xenarthra to be an ancient clade with a constant diversification rate through time with a species turnover driven by high but constant extinction. We also detected a significant negative correlation between speciation rate and past temperature fluctuations with an increase in speciation rate corresponding to the general cooling observed during the last 15 million years. Biogeographic reconstructions identified the tropical rainforest biome of Amazonia and the Guianan shield as the cradle of xenarthran evolutionary history with subsequent dispersions into more open and dry habitats.Fil: Gibb, Gillian C.. Universite de Montpellier; Francia. Massey Universit; Nueva ZelandaFil: Condamine, Fabien L.. University of Gothenburg; Suecia. Universite de Montpellier; Francia. University of Alberta; CanadáFil: Kuch, Melanie. McMaster University; CanadáFil: Enk, Jacob. McMaster University; CanadáFil: Moraes Barros, Nadia. Universidade Do Porto; Portugal. Universidade de Sao Paulo; BrasilFil: Superina, Mariella. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Poinar, Hendrik N.. McMaster University; CanadáFil: Delsuc, Frederic. Universite de Montpellier; Franci

    The Elbow-EpiTrainer : A method of delivering graded resistance to the extensor carpi radialis brevis. Effectiveness of a prototype device in a healthy population

    Get PDF
    This document is the Accepted Manuscript version of the following article: Navsaria R, Ryder DM, Lewis JS, et al, 'The Elbow-EpiTrainer: a method of delivering graded resistance to the extensor carpi radialis brevi:. Effectiveness of a prototype device in a healthy population', British Journal of Sports Medicine, Vol. 49(5):318-322, March 2015, available online at: http://bjsm.bmj.com/content/49/5/318. Published by the BMJ Publishing Group Limited.Background: Tennis elbow or lateral epicondylopathy (LE) is experienced as the lateral elbow has a reported prevalence of 1.3%, with symptoms lasting up to 18 months. LE is most commonly attributed to tendinopathy involving the extensor carpi radialis brevis (ECRB) tendon. The aim of tendinopathy management is to alleviate symptoms and restore function that initially involves relative rest followed by progressive therapeutic exercise. Objective: To assess the effectiveness of two prototype exercises using commonly available clinical equipment to progressively increase resistance and activity of the ECRB. Method: Eighteen healthy participants undertook two exercise progressions. Surface electromyography was used to record ECRB activity during the two progressions, involving eccentric exercises of the wrist extensors and elbow pronation exercises using a prototype device. The two progressions were assessed for their linearity of progression using repeated ANOVA and linear regression analysis. Five participants repeated the study to assess reliability. Results: The exercise progressions led to an increase in ECRB electromyographic (EMG) activity (p0.7) between the first and second tests for five participants. Conclusions: Manipulation of resistance and leverage with the prototype exercises was effective in creating significant increases of ECRB normalised EMG activity in a linear manner that may, with future research, become useful to clinicians treating LE. In addition, between trial reliability for the device to generate a consistent load was acceptable.Peer reviewe

    Immature myeloid cells directly contribute to skin tumor development by recruiting IL-17-producing CD4(+) T cells

    Get PDF
    Evidence links chronic inflammation with cancer, but cellular mechanisms involved in this process remain unclear. We have demonstrated that in humans, inflammatory conditions that predispose to development of skin and colon tumors are associated with accumulation in tissues of CD33(+)S100A9(+) cells, the phenotype typical for myeloid-derived suppressor cells in cancer or immature myeloid cells (IMCs) in tumor-free hosts. To identify the direct role of these cells in tumor development, we used S100A9 transgenic mice to create the conditions for topical accumulation of these cells in the skin in the absence of infection or tissue damage. These mice demonstrated accumulation of granulocytic IMCs in the skin upon topical application of 12-O-tetradecanoylphorbol-13-acetate (TPA), resulting in a dramatic increase in the formation of papillomas during epidermal carcinogenesis. The effect of IMCs on tumorigenesis was not associated with immune suppression, but with CCL4 (chemokine [C-C motif] ligand 4)-mediated recruitment of IL-17–producing CD4(+) T cells. This chemokine was released by activated IMCs. Elimination of CD4(+) T cells or blockade of CCL4 or IL-17 abrogated the increase in tumor formation caused by myeloid cells. Thus, this study implicates accumulation of IMCs as an initial step in facilitation of tumor formation, followed by the recruitment of CD4(+) T cells

    Geology-based and ecological processes of divergence between and within species of wingless darkling beetles

    Get PDF
    Aim: Discerning the relative role of geographical and ecological factors in promoting diversification is central to our understanding of the origin and maintenance of biodiversity. We explore the roles of geology and ecological tolerance in the diversification of a group of wingless beetles with low dispersal potential. Location: Western Mediterranean (Iberian Peninsula and North Africa). Taxon: Darkling beetles (Tenebrionidae: Misolampus). Methods: We sequenced nine gene fragments from the mitochondrial and nuclear genomes in all extant Misolampus species to reconstruct their phylogeny, evaluate species boundaries and potential contact zones and estimate divergence times. We modelled species distributions for different time periods to infer ecological preferences and assess the effects of climatic changes since the last interglacial. We used a time-stratified process-based biogeographical model to estimate ancestral areas of origin and the evolution of geographical ranges. Results: The palaeoclimatic model projections show contractions of favourable areas during the last interglacial period and mid-Holocene, and wide stretches of suitable areas during the last glacial maximum. Analyses of ancestral bioclimatic preferences reveal ecological adaptations in isolated lineages within three species. The phylogeny of Misolampus is strongly supported and unveils deep divergences within the six species. Two well-supported clades were recovered, one distributed in North Africa-Balearic Islands and another in the Iberian Peninsula. The divergence between the North African and Iberian clades occurred during the early Miocene. Biogeographical analyses infer an ancestral range including the Iberian, Betic and Rifean Plates, with subsequent splits followed by dispersal events. Main conclusions: Our results favour a dual role of vicariance and dispersal in driving the historical biogeography and diversification of Misolampus since the early Miocene. We also found evidence for incipient speciation events, underscoring the role of tectonic events and adaptation to local climatic conditions in the diversification of the group.Visit of PMP to the Institut des Sciences de l'Evolution de Montpellier (ISEM) was supported by the Ministerio de Ciencia, Innovación y Universidades, Spain (MICINN-FEDER) through contract BES-2016-077777. This study was supported by the Spanish government (MINECO/MIUC/AEI) and the European Fund for Regional Development (FEDER) under grants CGL2015-66571-P (collecting and Museum visits) and PID2019-110243GB-I00/AEI/10.13039/501100011033 (Ministerio de Ciencia, Innovación y Universidades, Spain) (molecular analyses) to MGP. Support of the publication fee was granted by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)

    Neogene History of the Amazonian Flora: A Perspective Based on Geological, Palynological, and Molecular Phylogenetic Data

    Get PDF
    The Amazon hosts one of the largest and richest rainforests in the world, but its origins remain debated. Growing evidence suggests that geodiversity and geological history played essential roles in shaping the Amazonian flora. Here we summarize the geo-climatic history of the Amazon and review paleopalynological records and time-calibrated phylogenies to evaluate the response of plants to environmental change. The Neogene fossil record suggests major sequential changes in plant composition and an overall decline in diversity. Phylogenies of eight Amazonian plant clades paint a mixed picture, with the diversification of most groups best explained by constant speciation rates through time, while others indicate clade-specific increases or decreases correlated with climatic cooling or increasing Andean elevation. Overall, the Amazon forest seems to represent a museum of diversity with a high potential for biological diversification through time. To fully understand how the Amazon got its modern biodiversity, further multidisciplinary studies conducted within a multimillion-year perspective are needed. ▪The history of the Amazon rainforest goes back to the beginning of the Cenozoic (66 Ma) and was driven by climate and geological forces. ▪In the early Neogene (23-13.8 Ma), a large wetland developed with episodic estuarine conditions and vegetation ranging from mangroves to terra firme forest. ▪In the late Neogene (13.8-2.6 Ma), the Amazon changed into a fluvial landscape with a less diverse and more open forest, although the details of this transition remain to be resolved. ▪These geo-climatic changes have left imprints on the modern Amazonian diversity that can be recovered with dated phylogenetic trees. ▪Amazonian plant groups show distinct responses to environmental changes, suggesting that Amazonia is both a refuge and a cradle of biodiversity

    Origin and diversification of living cycads: a cautionary tale on the impact of the branching process prior in Bayesian molecular dating

    Get PDF
    International audienceBackground: Bayesian relaxed-clock dating has significantly influenced our understanding of the timeline of biotic evolution. This approach requires the use of priors on the branching process, yet little is known about their impact on divergence time estimates. We investigated the effect of branching priors using the iconic cycads. We conducted phylogenetic estimations for 237 cycad species using three genes and two calibration strategies incorporating up to six fossil constraints to (i) test the impact of two different branching process priors on age estimates, (ii) assess which branching prior better fits the data, (iii) investigate branching prior impacts on diversification analyses, and (iv) provide insights into the diversification history of cycads.Results: Using Bayes factors, we compared divergence time estimates and the inferred dynamics of diversification when using Yule versus birth-death priors. Bayes factors were calculated with marginal likelihood estimated with stepping-stone sampling. We found striking differences in age estimates and diversification dynamics depending on prior choice. Dating with the Yule prior suggested that extant cycad genera diversified in the Paleogene and with two diversification rate shifts. In contrast, dating with the birth-death prior yielded Neogene diversifications, and four rate shifts, one for each of the four richest genera. Nonetheless, dating with the two priors provided similar age estimates for the divergence of cycads from Ginkgo (Carboniferous) and their crown age (Permian). Of these, Bayes factors clearly supported the birth-death prior.Conclusions: These results suggest the choice of the branching process prior can have a drastic influence on our understanding of evolutionary radiations. Therefore, all dating analyses must involve a model selection process using Bayes factors to select between a Yule or birth-death prior, in particular on ancient clades with a potential pattern of high extinction. We also provide new insights into the history of cycad diversification because we found (i) periods of extinction along the long branches of the genera consistent with fossil data, and (ii) high diversification rates within the Miocene genus radiations

    Southernmost record of MegadolodusMegadolodus (Litopterna, Proterotheriidae, Megadolodinae) from the late Middle Miocene of Fitzcarrald, Peruvian Amazonia, and mesowear analysis of diet in megadolodine litopterns

    Full text link
    Megadolodinae is a clade of tropical bunodont litopterns that includes three previously recognized species from Miocene fossil sites from northern South America. Here, we report an additional occurrence of Megadolodus molariformis from the Middle Miocene exposures at the Fitzcarrald arch (Peruvian Amazonia), based on dental material, which represents the southernmost record of the clade. This discovery further increases the faunal similarity between Fitzcarrald and the coeval La Venta fauna of Colombia. Given the convergent evolution of the bunodont dentition of megadolodines with suoids (Old World pigs and New World peccaries), we tested the hypothesis of frugivory in megadolodines with a mesowear angle approach using modern pigs and peccaries. These analyses differentiate the diet of modern suoids and suggest that megadolodines had a more abrasive diet than most of these taxa, except for the grazing warthogs. The dentition of megadolodines shows similar levels of abrasion to modern babirusas, thereby suggesting that the latter may represent an appropriate modern analog. Supplementary files are available for this article for free at www.tandfonline.com/UJVP

    A phylogenetic study to assess the link between biome specialization and diversification in swallowtail butterflies

    Get PDF
    The resource-use hypothesis, proposed by E.S. Vrba, states that habitat fragmentation caused by climatic oscillations would affect particularly biome specialists (species inhabiting only one biome), which might show higher speciation and extinction rates than biome generalists. If true, lineages would accumulate biome-specialist species. This effect would be particularly exacerbated for biomes located at the periphery of the global climatic conditions, namely, biomes that have high/low precipitation and high/low temperature such as rainforest (warm-humid), desert (warm-dry), steppe (cold-dry) and tundra (cold-humid). Here, we test these hypotheses in swallowtail butterflies, a clade with more than 570 species, covering all the continents but Antarctica, and all climatic conditions. Swallowtail butterflies are among the most studied insects, and they are a model group for evolutionary biology and ecology studies. Continental macroecological rules are normally tested using vertebrates, this means that there are fewer examples exploring terrestrial invertebrate patterns at global scale. Here, we compiled a large Geographic Information System database on swallowtail butterflies' distribution maps and used the most complete time-calibrated phylogeny to quantify diversification rates (DRs). In this paper, we aim to answer the following questions: (1) Are there more biome-specialist swallowtail butterflies than biome generalists? (2) Is DR related to biome specialization? (3) If so, do swallowtail butterflies inhabiting extreme biomes show higher DRs? (4) What is the effect of species distribution area? Our results showed that swallowtail family presents a great number of biome specialists which showed substantially higher DRs compared to generalists. We also found that biome specialists are unevenly distributed across biomes. Overall, our results are consistent with the resource-use hypothesis, species climatic niche and biome fragmentation as key factors promoting isolation

    Recent origin and rapid speciation of Neotropical orchids in the world's richest plant biodiversity hotspot

    Get PDF
    The Andean mountains of South America are the most species-rich biodiversity hotspot worldwide with c. 15% of the world's plant species, in only 1% of the world's land surface. Orchids are a key element of the Andean flora, and one of the most prominent components of the Neotropical epiphyte diversity, yet very little is known about their origin and diversification. We address this knowledge gap by inferring the biogeographical history and diversification dynamics of the two largest Neotropical orchid groups (Cymbidieae and Pleurothallidinae), using two unparalleled, densely sampled orchid phylogenies (including more than 400 newly generated DNA sequences), comparative phylogenetic methods, geological and biological datasets. We find that the majority of Andean orchid lineages only originated in the last 20–15 million yr. Andean lineages are derived from lowland Amazonian ancestors, with additional contributions from Central America and the Antilles. Species diversification is correlated with Andean orogeny, and multiple migrations and recolonizations across the Andes indicate that mountains do not constrain orchid dispersal over long timescales. Our study sheds new light on the timing and geography of a major Neotropical diversification, and suggests that mountain uplift promotes species diversification across all elevational zones.O.A.P-E. is supported by a Colombian National Science Foundation (COLCIENCIAS) scholarship and G.C. is supported by a German Science Foundation grant (RE 603/20). F.L.C. is supported by a Marie Curie grant (BIOMME project, IOF627684) and has benefited from an ‘Investissements d’Avenir’ grant managed by Agence Nationale de la Recherche (CEBA, ref. ANR-10-LABX-25-01). A.P.K. and D.B. were supported by grants from the Alberta Mennega Foundation. N.J.M. was supported by the National Institute for Mathematical and Biological Synthesis, an Institute sponsored by the National Science Foundation (NSF) through NSF Award no. EFJ0832858, with additional support from The University of Tennessee, Knoxville, and is currently supported by a Discovery Early Career Researcher Award DE150101773, funded by the Australian Research Council, and by The Australian National University. D.S. is funded by the Swedish Research Council (2015-04748). A.A. is supported by grants from the Swedish Research Council, the European Research Council under the European Union’s Seventh Framework Program (FP/2007-2013, ERC Grant Agreement no. 331024), the Swedish Foundation for Strategic Research and a Wallenberg Academy Fellowship
    corecore