994 resultados para St. Thomas, Ontario


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Glaciation over the Pleistocene induced dramatic range fluctuations for species across North America such that postglacial recolonization by southern refugial lineages has characterized the genetic structure of northern North American species. Based on the leading edge model of postglacial range expansion, dispersal and rapid population growth in these northern taxa is expected to produce vast areas of genetic homogeneity. Previous work on the widely distributed spring peeper (Pseudacris crucifer) revealed six distinct mitochondrial lineages that diverged between 3-11 mya, expanding and contracting with glacial cycles. Beginning 16,000 yBP, receding glaciers permitted Eastern lineage refugia residing in the southern Appalachians to migrate northward into the St. Lawrence Valley then westward through most of central Canada. Peripheral populations at the northwestern range limit of P. crucifer in central Manitoba are likely descended from this westward expanding Eastern lineage. According to the central-marginal hypothesis, founder effects from colonization as well as limited gene flow is expected to reveal genetic differentiation and lower genetic diversity in peripheral populations. The goal of my study is to further our understanding of peripheral range dynamics in peripheral Manitoba populations of P. crucifer by determining their genetic affinity and diversity relative to more central populations in Ontario and Minnesota. In this study I amplified and aligned cytochrome b sequences from sample sites across central Manitoba to reconstruct a Bayesian phylogeny for P. crucifer; additionally, microsatellite loci were genotyped to estimate genetic diversity. Results from this study affirmed Eastern lineage descent for peripheral Manitoba sites by aligning with Ontario. Initial colonization by the Interior lineage between glacial retreat and the appearance of arid vicariance events may explain the apparent introgression of non-Eastern lineages in Manitoba. However, genetic diversity measured in expected heterozygosity (H¬e) was not found to be significantly different in Manitoba genotypes. Greater isolation by distance and inbreeding relative to Ontario and Minnesota is likely the primary driver of genetic variation in these sites. Further sampling is necessary to generate a more complete genetic population structure for P. crucifer.

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Modern scientific world-view has undermined traditional myths, the functional survival of which seems to depend today in the West on a positivist justification. This would place them in the field of real History, through their study and revitalization by pseudoscientific disciplines such as the Atlantis and the ancient astronaut hypotheses. These have inspired new epic poems in (regular) verse that combine classic and/or biblical myths with a (pseudo)scientific modern world-view. For example, the critical rewriting of Noah’s myth by using the ancient astronaut hypothesis as a fictional device to produce a contemporary kind of plausibility allowed Abel Montagut to renew epic poetry, updating it also by adopting science fiction chronotopes in order to structure his fictional construction and to generate a high ethical sense for our time. Thus, his Poemo de Utnoa (1993) / La gesta d’Utnoa (1996), which has become a major classic of the literature in Esperanto thanks to its original version in this language, is a landmark of both science fiction and neo-biblical epics. This poem is written from a secular and purely literary perspective.

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