Continuous mitochondrial diversity of Danube sturgeon species over millennia: insights from ancient DNA

Sturgeons, an iconic group of large fishes inhabiting marine and freshwater ecosystems, have historically had significant economic and cultural value, particularly prized for their meat and roe (caviar). Furthermore, sturgeons play a vital ecological role as mesopredators of prey fish and invertebrates. In the Danube basin, the European (Acipenser sturio) and fringebarbel or ship sturgeon (Acipenser nudiventris) are locally extinct, while beluga (Huso huso), Russian (Acipenser gueldenstaedtii), stellate (Acipenser stellatus) and sterlet (Acipenser ruthenus) sturgeon have significantly declined since the nineteenth century owing to overfishing, habitat loss and pollution. Archaeological evidence suggests that sturgeon exploitation along the Danube began as early as 11.6 thousand years before the present. This study explores the genetic landscape of Danube sturgeons over the past approximately 10 000 years using ancient DNA (aDNA) from archaeological specimens. Despite challenges posed by limited sample size, phylogenetic analyses of mitochondrial genomes and the D-loop reveal high genetic diversity within beluga, Russian and ship sturgeon populations. In addition, shared haplotypes between modern and historical specimens of both beluga and Russian sturgeons suggest genetic continuity within each species over time. This study provides, to our knowledge, the first high-coverage sequencing of ancient sturgeon mitogenomes establishing the foundation for future aDNA research.This article is part of the theme issue 'Shifting seas: understanding deep-time human impacts on marine ecosystems'.