Limited hybridisation and introgression despite stocking among endemic Interior Highlands black basses (Centrarchidae: <i>Micropterus</i>)

Abstract Aim Smallmouth Bass ( Micropterus dolomieu ; SMB) are globally popular among anglers and have been widely introduced (i.e. stocked) for population management sportfishing. Importantly, stocking was prevalent before cryptic diversity within the SMB complex known, which now includes three newly elevated species: Neosho M. velox NB), Little River sp. cf. River; LRB) Ouachita OB). We sought to quantify structure hybridisation introgression in these recently described species. Location Species‐level diversity, particularly basin‐restricted LRB OB Mountains Central Interior Highlands (CIH), North America, suggests presence of distinct genetic variation that could be eroded by introgression. Methods estimated interspecific intraspecific differentiation species (SMB‐C) using 472 specimens comprising SMB, NB, OB, including naturally sympatric Spotted punctulatus SPB). Genomic samples were genotyped on a SNP panel 192 loci designed detect allele‐sharing multiple hierarchical levels. Results found low range‐wide between SMB‐C SPB (mostly backcrosses), heterozygosity varied, indicating differential Range‐wide CIH similar overall (but mostly F 2 backcrosses) observed streams with known connected reservoirs. Interspecific hybrids also generally lower, later‐generation backcrosses. strong (LRB Main Conclusions Despite isolated incidences natural (SPB) human‐mediated (SMB) introgression, genomic identity appears intact endemic suggesting potential ecological or behavioural isolating mechanisms preventing cross‐species reproduction. Our findings reveal remains cryptic, ecoregion may managed long‐term conservation.