Download or read book A Molecular Genetic Examination of the Polymorphic Arctic Charr Salvelinus Alpinus of Thingvallavatn Iceland microform written by John Volpe and published by National Library of Canada = Bibliothèque nationale du Canada. This book was released on 1995 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Genetic and Morphological Variation in Polymorphic Arctic Charr Salvelinus Alpinus from Icelandic Lakes written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evolutionary Significance of Genomic and Morphological Variation in Icelandic Arctic Charr Salvelinus Alpinus written by Eva Küttner and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Phenotypic Selection of Morphology in Polymorphic Arctic Charr Salvelinus Alpinus written by Oliver Franklin and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Considerable advances are being made in our understanding of divergent selection and ecological speciation. However, it remains unclear to what extent diversifying selection, responsible for divergence of distinct populations, also contributes to earlier stages of population diversification such as resource polymorphisms that persist despite gene flow. A general expectation of resource polymorphism is that phenotypic trade-offs influence fitness via trophic performance, resulting in disruptive selection. Despite numerous polymorphisms exhibiting morphological variation consistent with expectations of trophic trade-offs, there have been few attempts to examine these in the context of natural selection. As a result, we do not know how phenotype affects fitness and whether morphologically-based performance trade-offs contribute to the earliest stages of adaptive diversification. In this thesis, I evaluated the hypothesis that morphological trade-offs influence fitness via trophic performance, thus contributing to disruptive selection. First, I characterised the shape-dependence of resource use in polymorphic Arctic charr (Salvelinus alpinus) in two contrasting Icelandic lakes: Thingvallavatn and Vatnshlíðarvatn. In both lakes, resource use was shape-dependent consistent with biomechanical expectations differentiating morphs. However, shape-resource associations within morphs did not always correspond to patterns distinguishing morphs. I then estimated effects of shape on growth via trophic resource use, using a path analytical approach and calculating performance gradients. Though observations were consistent with disruptive selection of shape in Thingvallavatn, there were no effects in either lake consistent with the hypothesised function of trophic performance. Instead, I observed shape-dependent parasitism and non-trophic effects of shape influencing growth, and contrasting patterns of size-dependent mortality between coexisting morphs. Finally, I demonstrated the conditions under which performance gradients can be considered valid estimates of selection, and clarified what inferences can be made where direct estimates of fitness in nature are unobtainable. This thesis contributes to our understanding of early diversification by demonstrating inconsistencies between general expectations of adaptive mechanisms and processes evident in nature. Intuitive mechanisms such as morphological trade-offs in trophic performance might not affect fitness in the wild and expected phenotype-fitness relationships may arise from a complex of alternative mechanisms.
Download or read book Molecular Evolution and Adaptive Radiation written by Thomas J. Givnish and published by Cambridge University Press. This book was released on 2000-05-08 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume surveys advances in the study of adaptive radiation showing how molecular characters can be used to analyze the origin and pattern of diversification within a lineage in a non-circular fashion.
Download or read book The Evolutionary Biology of the Threespine Stickleback written by Michael A. Bell and published by Oxford University Press on Demand. This book was released on 1994 with total page 571 pages. Available in PDF, EPUB and Kindle. Book excerpt: The threespine stickleback is a small fish of temperate coastal and fresh waters that exhibits extraordinary phenotypic diversity. Benefiting from its amenability to observation in the field and manipulation in the laboratory, Niko Tinbergen pioneered the threespine stickleback's use in behavioral studies and established it as a model system in ethology. This up-to-date volume incorporates reviews from active researchers who use studies of the fish to address a broad variety of evolutionary issues, including optimal foraging, armor variation, speciation, and the endocrine basis for correlated behavioral characters. The work demonstrates the value of viewing the biology of a single organism simultaneously from multiple perspectives. Students and researchers in ecology, evolution, animal behavior, and vertebrate zoology will find much of interest in this useful book.
