Biological implications of a detailed repeat annotation in Octopus vulgaris

Abstract

Octopuses are phenotypically distinctive organisms, and recent genomic work raises questions about the contributions of transposable elements (TE) to their genomic architecture. We leveraged a robust repeat annotation pipeline, in combination with manual and automated curatorial techniques, to produce a more comprehensive repeat annotation of Octopus vulgaris. This revealed that [~]66% of the genome are repeats, in contrast to previous estimates of 43-50%. Whereas previous studies of TE expansion in Octopus bimaculoides identified two bursts of activity, 25 and 56 MYA, our re-annotation revealed four such expansions at 18, 25, 33, and 56 MYA. We further identified a landscape of TE hot- and cold spots. This much refined TE timescape and landscape will serve as a useful basis for understanding TE contributions to O. vulgaris evolution, and also for identifying factors contributing to variation in the TE community across genomic space and evolutionary time.