Historical Demographic Processes Dominate Genetic Variation in Ancient Atlantic Cod Mitogenomes

Ancient DNA (aDNA) approaches have been successfully used to infer the long-term impacts of climate change, domestication, and human exploitation in a range terrestrial species. Nonetheless, studies investigating such using aDNA marine species are rare. Atlantic cod ( Gadus morhua ), is an economically important that has experienced dramatic census population declines during last century. Here, we investigated 48 ancient mitogenomes from historical specimens obtained archeological excavations northern Europe dated up 6,500 BCE. We compare these those 496 modern conspecifics sampled across North Ocean adjacent seas. Our results confirm earlier observations high levels mitogenomic variation lack mutation-drift equilibrium—suggestive expansion. Furthermore, our temporal comparison yields no evidence measurable changes through time. Instead, indicate reflects past demographic processes driven by major events (such as oscillations sea level) subsequent gene flow rather than contemporary fluctuations stock abundance. contemporaneous anthropogenic pressures commercial fisheries had little impact on diversity wide-spread with cod. These do not contradict overfishing negative consequences for abundance importance genetic implementing conservation strategies. imply any measures toward recovery eastern Atlantic, will be constrained recent loss variation.