Elephantids are the world's most iconic megafaunal family, yet there is no comprehensive genomic assessment of their relationships. We report a total of 14 genomes, including 2 from the American mastodon, which is an extinct elephantid relative, and 12 spanning all three extant and three extinct elephantid species including an ∼120,000-y-old straight-tusked elephant, a Columbian mammoth, and woolly mammoths. Earlier genetic studies modeled elephantid evolution via simple bifurcating trees, but here we show that interspecies hybridization has been a recurrent feature of elephantid evolution. We found that the genetic makeup of the straight-tusked elephant, previously placed as a sister group to African forest elephants based on lower coverage data, in fact comprises three major components. Most of the straight-tusked elephant's ancestry derives from a lineage related to the ancestor of African elephants while its remaining ancestry consists of a large contribution from a lineage related to forest elephants and another related to mammoths. Columbian and woolly mammoths also showed evidence of interbreeding, likely following a latitudinal cline across North America. While hybridization events have shaped elephantid history in profound ways, isolation also appears to have played an important role. Our data reveal nearly complete isolation between the ancestors of the African forest and savanna elephants for ∼500,000 y, providing compelling justification for the conservation of forest and savanna elephants as separate species.
SummaryAdmixture graphs generalize phylogenetic trees by allowing genetic lineages to merge as well as split. In this paper we present the R package admixturegraph containing tools for building and visualizing admixture graphs, for fitting graph parameters to genetic data, for visualizing goodness of fit and for evaluating the relative goodness of fit between different graphs.Availability and ImplementationGitHub: https://github.com/mailund/admixture_graph and CRAN: https://cran.r-project.org/web/packages/admixturegraph.
An important aspect for any lexicographer to consider is the ease with which users will be able to acquire the necessary information from the data presented in the dictionary, whether electronic or printed. Furthermore, this aspect has high priority with users and reviewers. A distinction is proposed between two general types of lexicographical information costs. Firstly, searchrelated costs are the effort required by the look-up activities users have to perform when consulting a dictionary to find access to the data they are searching for. It is argued that the access route, article structure, data distribution and cross-references may influence search-related information costs positively as well as negatively. Secondly, comprehension-related costs are the effort connected to the user's ability to understand and interpret the data presented in a dictionary. In other words: How easy or difficult is it for users to understand the data presented? Examples show how textual condensation, dictionary functions and use-situations may impact on the level of comprehensionrelated information costs. It is thus possible to establish a framework for evaluating lexicographical information costs for the purpose of dictionary making, use, analysis and research. Keywords: LEXICOGRAPHY, DICTIONARY, INFORMATION COSTS, ACCESS ROUTES, DISTRIBUTION STRUCTURE, CROSS-REFERENCES, TEXTUAL CONDENSATION, DIC-TIONARY ARTICLES, SEARCH ZONES, DATA, INFORMATION, DICTIONARY FUNCTIONS, USE-SITUATIONSOpsomming: Die uitwerking van leksikografiese inligtingskoste op die maak en gebruik van woordeboeke. 'n Belangrike aspek vir enige leksikograaf om in ag te neem is die gemak waarmee gebruikers in staat sal wees om die nodige inligting van die data in die woordeboek, hetsy elektronies of gedruk, te verkry. Verder geniet hierdie aspek hoë voorkeur by gebruikers en resensente. 'n Onderskeid word voorgestel tussen twee algemene soorte leksikografiese inligtingskoste. Eerstens, soekverwante koste is die inspanning wat gepaardgaan met die opsoekaktiwiteite wat gebruikers moet verrig by die raadpleging van 'n woordeboek om toegang te verkry tot die data waarna hulle soek. Daar word geredeneer dat die toegangsroete, artikelstruktuur, dataverspreiding en kruisverwysings soekverwante inligtingskoste sowel positief as negatief kan beïnvloed. Tweedens, begripsverwante koste is die inspanning verbonde aan die gebruiker se vermoë om die gegewe data in 'n woordeboek te verstaan en te interpreteer. Met ander woorde: Hoe maklik of moeilik is dit vir gebruikers om die gegewe data te verstaan? Voor-* This article is partially based on a presentation made at the Thirteenth International Symposium on Lexicography at
Admixture graphs are mathematical structures that describe the ancestry of populations in terms of divergence and merging (admixing) of ancestral populations as a graph. An admixture graph consists of a graph topology, branch lengths, and admixture proportions. The branch lengths and admixture proportions can be estimated using numerous numerical optimization methods, but inferring the topology involves a combinatorial search for which no polynomial algorithm is known. In this paper, we present a reversible jump MCMC algorithm for sampling high-probability admixture graphs and show that this approach works well both as a heuristic search for a single best-fitting graph and for summarizing shared features extracted from posterior samples of graphs. We apply the method to 11 Native American and Siberian populations and exploit the shared structure of high-probability graphs to characterize the relationship between Saqqaq, Inuit, Koryaks, and Athabascans. Our analyses show that the Saqqaq is not a good proxy for the previously identified gene flow from Arctic people into the Na-Dene speaking Athabascans.
Populations of the common chimpanzee (Pan troglodytes) are in an impending risk of going extinct in the wild as a consequence of damaging anthropogenic impact on their natural habitat and illegal pet and bushmeat trade. Conservation management programmes for the chimpanzee have been established outside their natural range (ex situ), and chimpanzees from these programmes could potentially be used to supplement future conservation initiatives in the wild (in situ). However, these programmes have often suffered from inadequate information about the geographical origin and subspecies ancestry of the founders. Here, we present a newly designed capture array with ̴ 60 000 ancestry informative markers used to infer ancestry of individual chimpanzees in ex situ populations and determine geographical origin of confiscated sanctuary individuals. From a test panel of 167 chimpanzees with unknown origins or subspecies labels, we identify 90 suitable non-admixed individuals in the European Association of Zoos and Aquaria (EAZA) Ex situ Programme (EEP). Importantly, another 46 individuals have been identified with admixed subspecies ancestries, which therefore over time, should be naturally phased out of the breeding populations. With potential for future re-introduction to the wild, we determine the geographical origin of 31 individuals that were confiscated from the illegal trade and demonstrate the promises of using non-invasive sampling in future conservation action plans. Collectively, our genomic approach provides an exemplar for ex situ management of endangered species and offers an efficient tool in future in situ efforts to combat the illegal wildlife trade.
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