RT Journal Article SR Electronic T1 Unexpected post-glacial colonisation route explains the white colour of barn owls (Tyto alba) from the British Isles JF bioRxiv FD Cold Spring Harbor Laboratory SP 2021.04.23.441058 DO 10.1101/2021.04.23.441058 A1 Ana Paula Machado A1 Tristan Cumer A1 Christian Iseli A1 Emmanuel Beaudoing A1 Anne-Lyse Ducrest A1 Melanie Dupasquier A1 Nicolas Guex A1 Klaus Dichmann A1 Rui Lourenço A1 John Lusby A1 Hans-Dieter Martens A1 Laure Prévost A1 David Ramsden A1 Alexandre Roulin A1 Jérôme Goudet YR 2021 UL http://biorxiv.org/content/early/2021/04/23/2021.04.23.441058.abstract AB The climate fluctuations of the Quaternary shaped the movement of species in and out of glacial refugia. In Europe, the majority of species followed one of the described traditional postglacial recolonization routes from the southern peninsulas towards the north. Like most organisms, barn owls are assumed to have colonized the British Isles by crossing over Doggerland, a land bridge that connected Britain to northern Europe. However, while they are dark rufous in northern Europe, barn owls in the British Isles are conspicuously white, a contrast that could suggest selective forces are at play on the islands. However, analysis of known candidate genes involved in colouration found no signature of selection. Instead, using whole genome sequences and species distribution modelling, we found that owls colonised the British Isles soon after the last glaciation, directly from a white coloured refugium in the Iberian Peninsula, before colonising northern Europe. They would have followed a yet unknown post-glacial colonization route to the Isles over a westwards path of suitable habitat in now submerged land in the Bay of Biscay, thus not crossing Doggerland. As such, they inherited the white colour of their Iberian founders and maintained it through low gene flow with the mainland that prevents the import of rufous alleles. Thus, we contend that neutral processes likely explain this contrasting white colour compared to continental owls. With the barn owl being a top predator, we expect future research will show this unanticipated route was used by other species from its paleo community.Competing Interest StatementThe authors have declared no competing interest.