Geography, ecology, and history synergistically shape across-range genetic variation in a calanoid copepod endemic to the north-eastern Oriental.

This article focuses on the genetic variation and population structure of *Phyllodiaptomus tunguidus*, a calanoid copepod endemic to the northeastern Oriental region, testing the center-periphery hypothesis (CPH) which predicts lower genetic diversity in peripheral populations. Using mitochondrial and nuclear markers across 36 populations, the study found that *P. tunguidus* survived the Last Glacial Maximum (LGM) in three distinct refugia, leading to a complex genetic pattern not explained solely by geographic centrality. Ecological factors, particularly current climate conditions, explained more genetic variation than geographic or historical factors, though all three interacted significantly. The findings suggest that geographic, ecological, and historical influences synergistically shape genetic diversity in species inhabiting complex landscapes, challenging the universal applicability of the CPH.