The Intertidal North‐South Split: Oceanographic Features and Life History Shape the Phylogeography of Chiton Acanthochitona rubrolineata

ABSTRACT The genetic structure and demographic history of marine organisms are shaped by a variety of factors including biological and ecological characteristics, ocean currents, and the palaeogeological effects of sea‐level fluctuations. Here we present a comprehensive method combining population genomics, laboratory experiments, and ocean modelling in 13 populations of the chiton Acanthochitona rubrolineata along the coast of China. Based on demographic and population genomic analyses, significant divergence was observed between the Northern and Southern population groups, which are separated by the Yangtze River Estuary. The numerical circulation model simulation showed that gene flow and population connectivity were strongly influenced by ocean currents and the larval dispersal ability of chiton A. rubrolineata . These data thus clearly revealed the presence of two separately evolving lineages in chiton— A. rubrolineata northern and A. rubrolineata southern. Our study highlights that a robust understanding of organisms in the intertidal zone requires a comprehensive consideration of factors that influence gene flow and genetic structure, including the life‐history traits, coastal currents, geographic isolation, and habitat suitability. The life history of marine organisms, together with local oceanographic features, could ultimately drive the population divergence and lead to speciation. These findings provide a guideline for future analyses of non‐model and potentially threatened species and will aid in the conservation of biodiversity.