| Summary: | Trophic diversification of Arctic charr (Salvelinus alpinus, Linn. 1758) into four genetically distinct morphs, varying in life history characteristics, behavior, and trophic morphology, has occurred in lake Thingvallavatn following the last glaciation. The aim of this study was to investigate the genetic and developmental aspects of this diversification thereby gaining insights into the evolution and the maintenance of the Thingvallavatn morphs. In chapter I a population genetic screen of immunological candidate genes revealed differences among morphs for Cath2 and MHCII alpha that far exceeded differentiation at neutral loci. This is consistent with a scenario were selection has led to divergence in parts of the immune system. In chapter II embryonic and early post-hatching craniofacial cartilage development is described. The ontogenetic trajectories of shape and size indicated developmental heterochrony as a possible mechanism of morph divergence. Chapter III describes subtle but significant differences in early post-hatching craniofacial morphology between the progeny of three morphs of Arctic charr. Moreover hybrid progeny of two contrasting morphs showed extreme (or transgressive) phenotypes well outside of the parental range, indicating that the ecological divergence within the lake might be enhanced by lowered fitness of hybrids. In chapter IV the level of integration and modularity in craniofacial traits in morphs and hybrids is analysed. Chapter V describes the annotation of Arctic charr miRNAs expressed during development and analyses of candidate miRNAs involved in Arctic charr morphogenesis and diversification. Frá lokum síðustu ísaldar hafa þróast fjögur afbrigði bleikju (Salvelinus alpinus, Linn. 1758) innan Þingvallavatns. Afbrigðin eru erfðafræðilega aðgreind og eru ólík hvað snertir lífsferla, atferli og útlit, og á það sérstaklega við um líkamshluta er tengjast fæðuöflun. Markmið þessarar rannsóknar var að kanna erfðafræðilegar og þroskunarfræðilegar orsakir þessa fjölbreytileika og öðlast ...
|
|---|