Spatiotemporal genetic structure and demographic patterns of the mitre squid Uroteuthis chinensis in the Formosa Bank inferred from mitochondrial DNA

Uroteuthis chinensis, a commercially significant species distributed across the western Pacific, plays a vital role in marine fishery resources, accounting for up to 90% of the loliginid catch in several regions of China. However, there have been few genetic studies on this species exploring the relationship between its life history and genetic diversity. Therefore, this study aimed to address the genetic diversity and population structure of U. chinensis using 143 individuals collected from the coast of mainland China (Formosa Bank) based on the mitochondrial COI gene. Our results revealed high haplotype diversity (h = 0.906) and low nucleotide diversity in U. chinensis, a pattern consistent with recent demographic expansion following a period of reduced effective population size. Pairwise FST and analysis of molecular variance (AMOVA) revealed no significant genetic differentiation among the four sampling groups, suggesting an absence of detectable fine-scale spatiotemporal genetic structure within the Formosa Bank during the sampling period. In addition, demographic history analysis, based on Approximate Bayesian Computation (ABC), indicates that U. chinensis experienced a bottleneck event followed by a recent population expansion. These findings provide useful information for understanding the genetic diversity, demographic history, and sustainable management of this commercially important squid.