Missing the mark(er): pseudogenes identified through whole mitochondrial genome sequencing provide new insight into invasive lionfish genetics

Abstract

As documented marine invasions rise, determining the underlying molecular mechanisms of successful invasions is an immediate concern to management, but the relevance of such genetic studies hinges upon choosing the right markers. Most invasive lionfish phylogeography studies have used only the mitochondrial D-loop marker. For this study, three markers were targeted in invasive lionfish (n = 148): D-loop (mitochondrial), cytochrome oxidase I (mitochondrial), and S7 ribosomal intron-1 (nuclear). Using both mitochondrial and nuclear markers showed evidence of hybridization. At the D-loop marker, all sequences grouped with the Pacific Ocean lineage represented by Pterois volitans. At the S7 intron-1, all sequences grouped with the Indian Ocean S7 intron-1 haplotype associated with the Indian Ocean lineage represented by Pterois miles, showing discordance between the mitochondrial and nuclear markers. Further, at the COI marker, three out of 163 individuals sequenced matched P. miles. High throughput sequencing of the entire mitochondrial genome (n = 7) revealed that incongruence between mtDNA markers may be due to the insertion of mitochondrial DNA from P. volitans into the nuclear genome of fish genetically identified as P. miles. These data suggest hybridization and demonstrate that careful marker choice is important in future studies of lionfish genetics and invasive species in general.