Reference genome assembly of the false killer whale ( Pseudorca crassidens )

Abstract High-quality genomic resources are essential tools for conservation and management actions. We present a chromosome-level genome assembly for the false killer whale (Pseudorca crassidens, Owen, 1846), a large globicephaline delphinid found in tropical and subtropical waters. The final genome assembly is 2.7 Gb, with a scaffold N50 of 110.1 Mb, organized into 21 autosomes plus X and Y sex chromosomes. BUSCO scores were 97%, with low levels of duplicated and fragmented annotations. Repetitive elements were a larger proportion of the genome relative to most previously published cetacean genomes. Using this reference, we compared trends in historical demography and genome-wide heterozygosity in two North Pacific populations of false killer whales using short-read data mapped to the reference genome. Modeling of historical demography in these two populations indicate similar fluctuations in effective population size over time, reflecting shared ancestry until ~100-200 kya. Genome-wide heterozygosity levels were moderate relative to other cetaceans. The new genomic resources can facilitate further research on comparative genomics and can serve as a reference for other globicephaline cetaceans that currently lack chromosome-level genome assemblies.