5,111 research outputs found

    Extracting Lineage Information from Hand-Drawn Ancient Maps

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    In this paper, we present an efficient segmentation technique that extracts piecewise linear patterns from hand-drawn maps. The user is only required to place the starting and end points and the method is capable of extracting the route that connects the two, which closely colocates with the hand-drawn map. It provides an effective approach to interactively process and understand those historical maps. The proposed method employs supervised learning to evaluate at every pixel location the probability that such a lineage pattern exists, followed by shortest path segmentation to extract the border of interest

    The origin of the legumes is a complex paleopolyploid phylogenomic tangle closely associated with the cretaceous-paleogene (K-Pg) mass extinction event

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    This is the final version. Available from Oxford University Press via the DOI in this record. The consequences of the Cretaceous-Paleogene (K-Pg) boundary (KPB) mass extinction for the evolution of plant diversity remain poorly understood, even though evolutionary turnover of plant lineages at the KPB is central to understanding assembly of the Cenozoic biota. The apparent concentration of whole genome duplication (WGD) events around the KPB may have played a role in survival and subsequent diversification of plant lineages. To gain new insights into the origins of Cenozoic biodiversity, we examine the origin and early evolution of the globally diverse legume family (Leguminosae or Fabaceae). Legumes are ecologically (co-)dominant across many vegetation types, and the fossil record suggests that they rose to such prominence after the KPB in parallel with several well-studied animal clades including Placentalia and Neoaves. Furthermore, multiple WGD events are hypothesized to have occurred early in legume evolution. Using a recently inferred phylogenomic framework, we investigate the placement of WGDs during early legume evolution using gene tree reconciliation methods, gene count data and phylogenetic supernetwork reconstruction. Using 20 fossil calibrations we estimate a revised timeline of legume evolution based on 36 nuclear genes selected as informative and evolving in an approximately clock-like fashion. To establish the timing of WGDs we also date duplication nodes in gene trees. Results suggest either a pan-legume WGD event on the stem lineage of the family, or an allopolyploid event involving (some of) the earliest lineages within the crown group, with additional nested WGDs subtending subfamilies Papilionoideae and Detarioideae. Gene tree reconciliation methods that do not account for allopolyploidy may be misleading in inferring an earlier WGD event at the time of divergence of the two parental lineages of the polyploid, suggesting that the allopolyploid scenario is more likely. We show that the crown age of the legumes dates to the Maastrichtian or early Paleocene and that, apart from the Detarioideae WGD, paleopolyploidy occurred close to the KPB. We conclude that the early evolution of the legumes followed a complex history, in which multiple auto- and/or allopolyploidy events coincided with rapid diversification and in association with the mass extinction event at the KPB, ultimately underpinning the evolutionary success of the Leguminosae in the Cenozoic.Swiss National Science FoundationUniversity of ZurichNatural Sciences and Engineering Research Council of CanadaNational Environment Research CouncilFonds de la Recherche Scientifique of Belgiu

    Reconstructing an Ancestral Mammalian Immune Supercomplex from a Marsupial Major Histocompatibility Complex

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    The first sequenced marsupial genome promises to reveal unparalleled insights into mammalian evolution. We have used theMonodelphis domestica (gray short-tailed opossum) sequence to construct the first map of a marsupial major histocompatibility complex (MHC). The MHC is the most gene-dense region of the mammalian genome and is critical to immunity and reproductive success. The marsupial MHC bridges the phylogenetic gap between the complex MHC of eutherian mammals and the minimal essential MHC of birds. Here we show that the opossum MHC is gene dense and complex, as in humans, but shares more organizational features with non-mammals. The Class I genes have amplified within the Class II region, resulting in a unique Class I/II region. We present a model of the organization of the MHC in ancestral mammals and its elaboration during mammalian evolution. The opossum genome, together with other extant genomes, reveals the existence of an ancestral “immune supercomplex” that contained genes of both types of natural killer receptors together with antigen processing genes and MHC genes

    Deep sequencing of Ptilidium (Ptilidiaceae) suggests evolutionary stasis in liverwort plastid genome structure

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    Background and aims – Organellar genome sampling is patchy for non-vascular groups, with the earliest land plants poorly represented; currently only two liverworts, two mosses and one hornwort have sequenced, annotated plastid genomes. This is in part due to methodological difficulties that have hampered attempts to generate plastid genome data from liverworts. In this paper we present a method that overcomes some of the inherent difficulties by circumventing the need for plastid enrichment, but that also provides other valuable information from nuclear and mitochondrial regions including sequences from loci that may be phylogenetically useful, and potential population-level markers such as single nucleotide polymorphisms and microsatellites. Methods – A shotgun library developed from total genomic liverwort DNA was subjected to high-throughput pyrosequencing using the Roche 454 platform. Plastid reads were bioinformatically identified, assembled and annotated. To maximize usage of the vast number of reads generated using 454 sequencing technology, combined nuclear, mitochondrial and plastid contigs were also screened for microsatellite markers, and presumed nuclear contigs were scanned for protein domains. Key Results – This is the first plastid genome to be assembled for a leafy liverwort (i.e. Ptilidium) and also the first such genome to be sequenced using next generation technology for any bryophyte. The 119,007 base long plastid genome of Ptilidium pulcherrimum contains 88 protein-coding genes, four rRNAs and thirty tRNAs. The Inverted Repeat occurs between trn V-GAC and trn N-GUU. Functional copies of the two plastid-encoded sulphate import protein-coding genes (cysA and cysT) are absent, although pseudogenes are present in the same position that the functional genes occupy in Marchantia. Microsatellites: 197 novel potential primer pairs for P. pulcherrimum were found. Presumed nuclear Ptilidium contigs gave multiple hits to Class I transposable elements. Conclusions – The arrangement of genes is identical to the plastid of the complex thalloid liverwort Marchantia, suggesting that structural rearrangements are rare in hepatics. This dataset represents a valuable resource for novel phylogenetic and population level marker design in hepatics

    Research and Documentation in the 21st Century: Oral History and Genealogy of the Yuan Shikai Family

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    The oral histories and genealogies have long been used by historians, archaeologists, sociologists, ethnologists, and demographers in their investigation of past human behavior on social and historical evidences relating to a lineage organization or a clan. Chinese genealogical records has been used for thousands of years to record the genealogical history of a family, including a family’s origin, its subordinate lines, names and ages of the members, records of marriages, births and deaths, merits and deeds, and in early days brief biographical information of solely the male family members. This paper will examine the history of Chinese names and the genealogical records for jiapu. It details the significance of Chinese names and introduces the types of Chinese names and their meanings, followed by the history and development of surnames, clan names, and generation names. The highlight of paper includes the oral history and genealogy of the Xiangcheng Yuan family tracing to the lineage of Yuan Shikai, the first President of the Republic of China. In this genealogical study, the author examines the genealogical chart of the Yuan family on iron plate (Yuan Shi Tie Pai Jiapu) and the stone tablet in the Yuan Family Chapel (Yuan Shi Jia Miao Bei) based on their value, functions, and importance. The Yuan genealogy was identified as a source for the study of Chinese genealogies in relation to the Chinese polygamy, family structure, demography, economic conditions, generational orders, and social and political studies. The paper ends with the library documentation, preservation, and research in the 21st century focusing on the importance of Chinese family history and genealogical research for jiapu. A selected bibliography about the Yuan Shikai family is included at the end for further readings. Highlights ● History of Chinese Names and Genealogical Records ● Types of Chinese Names and their Meanings ● Oral History and Genealogy of the Yuan Shikai Family ● Resource and Documentation on Chinese Genealogy ● Library Cooperation and Resource-sharing on Chinese Genealog

    Reticulation, Data Combination, and Inferring Evolutionary History: An Example from Danthonioideae (Poaceae)

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    We explore the potential impact of conflicting gene trees on inferences of evolutionary history above the species level. When conflict between gene trees is discovered, it is common practice either to analyze the data separately or to combine the data having excluded the conflicting taxa or data partitions for those taxa (which are then recoded as missing). We demonstrate an alternative approach, which involves duplicating conflicting taxa in the matrix, such that each duplicate is represented by one partition only. This allows the combination of all available data in standard phylogenetic analyses, despite reticulations. We show how interpretation of contradictory gene trees can lead to conflicting inferences of both morphological evolution and biogeographic history, using the example of the pampas grasses, Cortaderia. The characteristic morphological syndrome of Cortaderia can be inferred as having arisen multiple times (chloroplast DNA [cpDNA]) or just once (nuclear ribosomal DNA [nrDNA]). The distributions of species of Cortaderia and related genera in Australia/New Guinea, New Zealand, and South America can be explained by few (nrDNA) or several (cpDNA) dispersals between the southern continents. These contradictions can be explained by past hybridization events, which have linked gains of complex morphologies with unrelated chloroplast lineages and have erased evidence of dispersals from the nuclear genome. Given the discrepancies between inferences based on the gene trees individually, we urge the use of approaches such as ours that take multiple gene trees into accoun
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