UC Santa Cruz

Holacanthus angelfishes are some of the most iconic marine fishes of the Tropical Eastern Pacific (TEP). However, very limited genomic resources currently exist for the genus. In this study we: (i) assembled and annotated the nuclear genome of the King Angelfish (Holacanthus passer), and (ii) examined the demographic history of H. passer in the TEP. We generated 43.8 Gb of ONT and 97.3 Gb Illumina reads representing 75× and 167× coverage, respectively. The final genome assembly size was 583 Mb with a contig N50 of 5.7 Mb, which captured 97.5% of the complete Actinoterygii Benchmarking Universal Single-Copy Orthologs (BUSCOs). Repetitive elements accounted for 5.09% of the genome, and 33,889 protein-coding genes were predicted, of which 22,984 were functionally annotated. Our demographic analysis suggests that population expansions of H. passer occurred prior to the last glacial maximum (LGM) and were more likely shaped by events associated with the closure of the Isthmus of Panama. This result is surprising, given that most rapid population expansions in both freshwater and marine organisms have been reported to occur globally after the LGM. Overall, this annotated genome assembly provides a novel molecular resource to study the evolution of Holacanthus angelfishes, while facilitating research into local adaptation, speciation, and introgression in marine fishes.