| Summary: | For their sensitivity to environmental variables, their impact on early developmental processes and their importance to the establishment of multiple phenotypes, epigenetic mechanisms have been increasingly studied during the last decades. Like other molecular processes at play in building and shaping adaptive diversity, they can be studied over a wide range of species at different taxonomic levels. Broader levels, such as within vertebrate groups, allow for the identification of signals that have over time become assimilated while narrower levels, such as within species morphotypes, allow for the identification of molecular signals in the first stages of speciation, which might get lost over longer evolutionary periods. The four Arctic charr morphs of Lake Thingvallavatn are an example of morphotypes within species, and are a useful tool to assess molecular differences between recently diverged groups. In this thesis, I investigated DNA methylation and gene expression differences between these four morphs during early development (Paper I), I identified correlations between the divergence of genome, transcriptome, and methylome in three of these morphs (Paper II) and I reviewed the state of knowledge about DNA methylation reprogramming in teleosts (Paper III). This jointly adds an important perspective to the field of evolutionary and developmental epigenetics. Þegar svipgerðareinkenni erfast án þess að vera beinlínis skráð í DNA er talað um umframerfðir. Það hversu næmir ferlarnir að baki umframerfðum eru fyrir umhverfisþáttum, áhrif þeirra á snemmþroskun, og þar af leiðandi mikilvægi þeirra fyrir myndun svipgerðar hefur á síðustu áratugum vakið athygli þróunarfræðinga, sem hafa í auknum mæli leitast við að samþætta þessi ferli inn í viðteknar kenningar þróunarfræðinnar. Til að mögulegt sé að greina og skilja hin ýmsu lífefnaferli sem tengjast tilurð aðlaganna er nauðsynlegt að rannsaka margar bæði fjarskylda og náskylda hópa lífvera. Breiðari flokkunareiningar, eins og t.d. innan hryggdýra, gera það kleift ...
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