Chromosome-Level Genome Assembly of the Cape Cliff Lizard (Hemicordylus capensis)

Abstract

Squamates represent a highly diverse and species-rich vertebrate group that is remarkably understudied from a genomic perspective. A scarcity of genomic data is particularly evident for scincomorph lizards, which encompass over 10% of all living squamates, and for which high-quality genomic resources are currently lacking. To address this knowledge gap, we present the first chromosome-level reference genome for this group, generated from a male Cape cliff lizard (Hemicordylus capensis), using highly accurate PacBio HiFi long-read sequencing data, long-range Omni-C chromosomal conformation capture data and transcriptomic data for annotation. The rHemCap1.1 genome assembly spans 2.29 Gb, with a scaffold N50 of 359.65 Mb, and includes 25,300 protein-coding genes, with a BUSCO completeness score of 95.5% (sauropsida_odb10). We have generated the most contiguous and complete chromosome-level squamate reference genome assembly publicly available to date. Furthermore, we used short-read resequencing of 35 males and females and applied a differential coverage approach to infer the sex-determination system of the species, which was previously unknown. Our results suggest this species has XX/XY sex chromosomes, representing the first evidence of sex determination in the family Cordylidae. This reference genome will help to establish this species as an evolutionary model for studying variation in body armor, a key trait in cordylids and other squamate groups. Lastly, this is the first squamate reference genome from a continental African species and, as such, represents a valuable resource not only for further evolutionary research in cordylids but also in closely related groups.

Keywords: Cordylidae; HiFi; Scincomorpha; reference genome; sex determination; squamates.