Mitogenomic insights into the population structure and demographic history of zig-zag eels (Mastacembelus armatus) in southern China

Abstract

Understanding the genetic diversity and population structure of both wild and cultured fish populations is essential for developing effective conservation strategies and enhancing artificial breeding practices in aquaculture. Mastacembelus armatus (zig-zag eel) is an economically important fish species, yet some wild populations are facing declines, and large-scale artificial breeding remains challenging. To address this, we conducted a comprehensive analysis of genetic diversity and structure in wild and cultured populations. In this study, we sequenced and assembled the mitochondrial genomes of 98 wild and 90 cultured individuals. The results showed high genetic diversity in both wild and cultured populations and gene flow between them was detected. Significant genetic differentiation was observed among wild populations, primarily driven by river isolation. Conversely, genetic homogenization and low genetic differentiation were found within the Pearl River system. Phylogenetic analysis identified two main lineages, and demographic analyses revealed that lineage diversification occurred during the Pleistocene epoch, likely driven by habitat fragmentation caused by glacial retreats and fluctuating river systems. This study provides valuable genetic insights into the wild and cultured M. armatus populations in southern China, highlighting the need to preserve genetic differentiation in wild populations and addressing the genetic impact of escaped or released cultured individuals through improved management practices.