G C A T T A C G G C A T genes Article Latitudinal Cline in Chromosome Numbers of Ice Cod A. glacialis (Gadidae) from Northeast Greenland Laura Ghigliotti 1,* , Jørgen S. Christiansen 2,3, Erica Carlig 1, Davide Di Blasi 1 and Eva Pisano 1 1 National Research Council of Italy, Institute for the Study of the Anthropic Impacts and the Sustainability of the Marine Environment (IAS) via De Marini 6, 16149 Genoa, Italy;
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[email protected] Received: 20 November 2020; Accepted: 15 December 2020; Published: 18 December 2020 Abstract: The ice cod Arctogadus glacialis (Peters, 1872) is one of the few fish species endemic to the Arctic. With a circumpolar distribution, the species is confined to the fjords and shelves of the Arctic seas. Biological information on A. glacialis is scarce, with genomic information restricted to microsatellites. Within the frame of the TUNU-Programme: Arctic Ocean Fishes—Diversity, Adaptation and Conservation, we studied A. glacialis at the chromosomal level to explore fish diversity and evolutionary aspects. The analysis of over 50 individuals from the Northeast Greenland fjords between latitudes 71◦090 N and 76◦420 N revealed a remarkable intraspecific diversity epitomized by chromosome numbers spanning from 28 to 33, the occurrence of putative B chromosomes, and diversified patterns of distribution of heterochromatin and rDNAs.