Multi‐Marker Mitochondrial Analysis Reveals Genetic Diversity and Phylogenetic Relationships of Black Sea Sturgeons (Acipenseridae)

ABSTRACT

Sturgeons represent a critical taxon for conservation due to their complex genetic structure and vulnerability to anthropogenic pressures, including poaching, overfishing, and habitat loss. This study provides a multi‐level mitochondrial characterization of four sturgeon species from the Black Sea basin and its associated migratory corridors ( Acipenser stellatus , Acipenser ruthenus , Acipenser gueldenstaedtii , and Huso huso ) to inform conservation management. The first dataset comprised 32 complete mitochondrial genomes retrieved from the NCBI RefSeq database, 24 from species of the family Acipenseridae , six hybrids, and two outgroups, used for phylogenetic inference within the family. The second dataset consisted of Cytochrome B (Cyt B) sequences retrieved from the NCBI GenBank database for Huso huso ( n  = 11), Acipenser gueldenstaedtii ( n  = 28), Acipenser stellatus ( n  = 171), and Acipenser ruthenus ( n  = 51), representing populations inhabiting the Black Sea basin and its migratory tributaries. The third dataset included D‐loop control region sequences, also sourced from NCBI GenBank, for the anadromous species comprising Acipenser stellatus ( n  = 183), Huso huso ( n  = 95), and Acipenser gueldenstaedtii ( n  = 35), used to assess population‐level variation and demographic trends. Comparative analyses revealed substantially higher polymorphism in the D‐loop region, enabling fine‐scale resolution of genetic diversity and demographic history that were masked by the more conserved Cyt B gene. Neutrality tests uncovered contrasting demographic signals: negative Tajima's D values in Acipenser stellatus indicate a recent population expansion, while significantly positive D‐loop values in Acipenser gueldenstaedtii point to a severe and recent bottleneck. Acipenser ruthenus exhibited moderate haplotypic diversity, suggesting historical expansion, whereas Huso huso displayed limited variation, indicative of ongoing genetic erosion. These findings highlight the necessity of developing species‐specific conservation strategies tailored to the genetic structures revealed in the Ponto‐Caspian region and provide a robust framework for captive‐breeding and habitat‐restoration programs essential to the recovery of these critically endangered species.