3 resultados para Histories

em DigitalCommons@University of Nebraska - Lincoln


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Right whales carry large populations of three ‘whale lice’ (Cyamus ovalis, Cyamus gracilis, Cyamus erraticus) that have no other hosts. We used sequence variation in the mitochondrial COI gene to ask (i) whether cyamid population structures might reveal associations among right whale individuals and subpopulations, (ii) whether the divergences of the three nominally conspecific cyamid species on North Atlantic, North Pacific, and southern right whales (Eubalaena glacialis, Eubalaena japonica, Eubalaena australis) might indicate their times of separation, and (iii) whether the shapes of cyamid gene trees might contain information about changes in the population sizes of right whales. We found high levels of nucleotide diversity but almost no population structure within oceans, indicating large effective population sizes and high rates of transfer between whales and subpopulations. North Atlantic and Southern Ocean populations of all three species are reciprocally monophyletic, and North Pacific C. erraticus is well separated from North Atlantic and southern C. erraticus. Mitochondrial clock calibrations suggest that these divergences occurred around 6 million years ago (Ma), and that the Eubalaena mitochondrial clock is very slow. North Pacific C. ovalis forms a clade inside the southern C. ovalis gene tree, implying that at least one right whale has crossed the equator in the Pacific Ocean within the last 1–2 million years (Myr). Low-frequency polymorphisms are more common than expected under neutrality for populations of constant size, but there is no obvious signal of rapid, interspecifically congruent expansion of the kind that would be expected if North Atlantic or southern right whales had experienced a prolonged population bottleneck within the last 0.5 Myr.

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In August 1925, University of Oxford anthropologist Beatrice Blackwood spent two days on the Blood Reserve in southern Alberta, home to the Kainai Nation. Assisted by the Indian Agent, she toured the reserve and took 33 photographs. Blackwood was investigating potential links among "race," culture, and environment, and some of her photographs were anthropometric in nature. Others, showing men working in fields or girls at residential school, portrayed a culture in transition. Upon her return to Britain, Blackwood deposited the Kainai photographs with Oxford's Pitt Rivers Museum.

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Discusses the taxonomy and life histories of two North American species of Carneophallus" (=Microphallus) (Digenea: Microphallidae).