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Bennett J.A.,University of Alberta | Lamb E.G.,University of Saskatchewan | Hall J.C.,University of Alberta | Cardinal-Mcteague W.M.,University of Alberta | And 3 more authors.
Ecology Letters | Year: 2013

That competition is stronger among closely related species and leads to phylogenetic overdispersion is a common assumption in community ecology. However, tests of this assumption are rare and field-based experiments lacking. We tested the relationship between competition, the degree of relatedness, and overdispersion among plants experimentally and using a field survey in a native grassland. Relatedness did not affect competition, nor was competition associated with phylogenetic overdispersion. Further, there was only weak evidence for increased overdispersion at spatial scales where plants are likely to compete. These results challenge traditional theory, but are consistent with recent theories regarding the mechanisms of plant competition and its potential effect on phylogenetic structure. We suggest that specific conditions related to the form of competition and trait conservatism must be met for competition to cause phylogenetic overdispersion. Consequently, overdispersion as a result of competition is likely to be rare in natural communities. © 2013 John Wiley & Sons Ltd/CNRS. Source


Stewart K.M.,Canadian Museum of Nature
Journal of Human Evolution | Year: 2014

Eastern and southern Africa experienced ongoing climatic and tectonic instability in the Plio-Pleistocene, alongside declining forests and expanding grasslands. Most known hominin genera (. Australopithecus spp., Kenyanthropus, Paranthropus spp., Homo spp.) appear roughly between 4.2 and 1.8Ma (millions of years ago). Explanations for these speciation events have focused on adaptations to environmental change, particularly in terrestrial biomes. However, the links between environmental change and hominin adaptations have not always been clear. Often overlooked is that Plio-Pleistocene vegetation included not just terrestrial environments, but a large component of edaphic (wet) C4 grasses and sedges. In this paper it is suggested that in response to environmental fluctuations, hominins engaged in conservative long-term ecological and dietary patterns, based on predictable C4/C3 wetland and terrestrial resources. Data are presented from six hominin locales, which demonstrate reliance on plant-based resources (sedges, grasses, and other vegetation) in C4-inclusive wetland/savanna mosaics. After roughly 2.4Ma, severe climate variability is associated with early Homo and perhaps Paranthropus boisei broadening their diet to familiar but less preferred foods: vertebrates and invertebrates. These foods consistently provided early Homo with essential nutrients, which reduced selection pressures and allowed for increases in brain size. After 1.65Ma, a 20% increase in the C4 dietary component of Homo occurs alongside increased relative brain size. P.boisei also increases its C4 dietary component by 15% after 1.65Ma. These increases imply that both taxa continued to broaden their diet within the C4-based wetlands/savanna biome, with Homo putting a greater emphasis on mammals. © 2014. Source


Bain R.H.,Canadian Museum of Nature | Hurley M.M.,CNRS Center for Marine Biodiversity, Exploitation and Conservation
Bulletin of the American Museum of Natural History | Year: 2011

Indochina (Laos, Cambodia, and Vietnam) houses over 600 species of amphibians and reptiles, roughly a quarter of which has been described within the last 15 years. Herein, we undertake the first biogeographic synthesis of the regional herpetofauna since the first half of the 20th century. We review the literature to measure and map species richness and endemism, the contributions of regional faunas, and ecological characteristics of Indochina's amphibians (Anura, Caudata), and reptiles (Serpentes, Sauria, Testudines, Crocodylia). Dividing Indochina into 19 subregions defined by topography and geology, we estimate the similarity among the regional faunas and appraise the effects of area and survey effort on these comparative analyses. Variation in species composition is broadly correlated with topography, habitat complexity, and proximity to regions outside Indochina. Indochina's herpetofauna is dominated (in decreasing order) by endemic species, widely distributed species, a South China fauna, and a biota centered in Thailand and Myanmar. Species richness is highest in amphibians and snakes, and peaks in upland forests. Endemism, highest among amphibians and lizards, also peaks in forests of the region's northern uplands and Annamite Range. Endemic species occupy a narrower range of habitats than nonendemics. Patterns of richness and endemism are partially explained by ecological constraints: amphibians and lizards are more restricted to forests than snakes, turtles, and crocodiles; amphibians are more restricted to uplands, turtles to lowlands. We also assess biogeography in the context of Indochina's geology, climate, and land cover. In northern Indochina, the Red River either acts as or coincides with an apparent dispersal barrier. Herpetofauna in northeastern upland areas are closely allied with fauna of southeastern China. In southern Indochina there is little evidence that the Mekong River represents a biogeographic barrier to the regional herpetofauna. The Annamite Range is composed of at least three distinct units and its elevated species richness and endemism are also noted in adjacent lowlands. Contribution of subtropical biota to Indochina's fauna is significantly greater than that of tropical biota and there is little other evidence for intermixing at intermediate latitudes. Our results have implications for biogeography and conservation efforts, although they must be viewed in the context of rapidly evolving systematic knowledge of the region's amphibians and reptiles. Future survey efforts, and the phylogenetic analyses that come from them, are essential for supporting regional conservation efforts, as they will better resolve the known patterns of amphibian and reptile richness and endemism. © 2011 American Museum of Natural History. Source


Harington C.R.,Canadian Museum of Nature
Journal of Cave and Karst Studies | Year: 2011

Highlights of ice-age vertebrate faunas from Canadian caves are presented in geographic order (east to west). They include four each from Quebec and Ontario; three from Alberta; one from Yukon; and ten from British Columbia. Localities, vertebrate species represented, radiocarbon ages, and paleoenvironmental evidence are mentioned where available, as well as pertinent references. Of these caves, perhaps Bluefish Caves, Yukon, are most significant, because they contain evidence for the earliest people in North America. Tables provide lists of species and radiocarbon ages from each site. Source


Underwood C.J.,Birkbeck College | Cumbaa S.L.,Canadian Museum of Nature
Palaeontology | Year: 2010

Abstract: Acid preparation of samples of a bonebed from the Cenomanian of central Canada yielded several thousand well-preserved chondrichthyan teeth, in addition to numerous other vertebrate remains. Teeth and other remains of one species of chimaeroid, one species of hybodont shark, three species of Ptychodus, 10 species of neoselachian sharks and two species of batoid were recorded. The family Archaeolamnidae fam. nov., genera Meristodonoides gen. nov. and Telodontaspis gen. nov. and species Ptychodus rhombodus sp. nov., Telodontaspis agassizensis gen et sp. nov., Eostriatolamia paucicorrugata sp. nov., Roulletia canadensis sp. nov., Cretorectolobus robustus sp. nov. and Orectoloboides angulatus sp. nov. are described. Status of the genus Palaeoanacorax and the species Cretoxyrhina denticulata, Squalicorax curvatus and '. Rhinobatos'. incertus are discussed, and reconstructed dentitions of Archaeolamna and Roulletia presented. The fauna is of low diversity and dominated by active hunters, with many species apparently endemic to the northern Western Interior Seaway. © The Palaeontological Association. Source

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