Genomic data resolve long-standing uncertainty by distinguishing white marlin (<i>Kajikia albida</i>) and striped marlin (<i>K. audax</i>) as separate species

Abstract Large pelagic fishes are often broadly distributed and capable of long-distance movements. These factors can promote gene flow that makes it difficult to disentangle intra- vs. inter-specific levels genetic differentiation. Here, we assess the relationship two istiophorid billfishes, white marlin (Kajikia albida) striped (K. audax), presently considered sister species inhabiting separate ocean basins. Previous studies report differentiation between these smaller than those observed among populations other species. To determine whether comprise or a single globally species, surveyed 2520 nucleotide polymorphisms (SNPs) in 62 242 across Atlantic, Pacific, Indian oceans. Multivariate analyses resolved as distinct groups, tree composed lineages was strongly supported over lineage tree. Genetic (FST = 0.5384) also substantially larger 0.0192–0.0840), identified SNPs allow unambiguous identification. Our findings indicate which estimate diverged at approximately 2.38 Mya.