Monitor lizards are unique among ectothermic reptiles in that they have high aerobic capacity and distinctive cardiovascular physiology resembling that of endothermic mammals. Here, we sequence the genome of the Komodo dragon Varanus komodoensis, the largest extant monitor lizard, and generate a high-resolution de novo chromosome-assigned genome assembly for V. komodoensis using a hybrid approach of long-range sequencing and single-molecule optical mapping. Comparing the genome of V. komodoensis with those of related species, we find evidence of positive selection in pathways related to energy metabolism, cardiovascular homoeostasis, and haemostasis. We also show species-specific expansions of a chemoreceptor gene family related to pheromone and kairomone sensing in V. komodoensis and other lizard lineages. Together, these evolutionary signatures of adaptation reveal the genetic underpinnings of the unique Komodo dragon sensory and cardiovascular systems, and suggest that selective pressure altered haemostasis genes to help Komodo dragons evade the anticoagulant effects of their own saliva. The Komodo dragon genome is an important resource for understanding the biology of monitor lizards and reptiles worldwide.

B U Bioscience Wageningen University Wageningen The Netherlands

Cardiovascular Research Institute University of California San Francisco CA USA

Centre for Integrative Ecology Deakin University Waurn Ponds Victoria Australia

Chan Zuckerberg BioHub San Francisco CA USA

Department of Biology University of Florence Sesto Fiorentino Italy

Department of Comparative Biomedicine and Food Science University of Padova Legnaro Italy

Department of Dermatology University of California San Francisco CA USA

Department of Ecology and Evolutionary Biology School of Biological Sciences University of California Irvine CA USA

Department of Ecology Charles University Prague Czech Republic

Department of Epidemiology and Biostatistics University of California San Francisco CA USA

Department of Pediatrics University of California San Francisco CA USA

Gladstone Institutes San Francisco CA USA

Institute for Computational Health Sciences University of California San Francisco CA USA

Institute for Conservation Research San Diego Zoo Escondido CA USA

Institute for Human Genetics University of California San Francisco CA USA

Institute of Animal Physiology and Genetics The Czech Academy of Sciences Liběchov Czech Republic

Institute of Molecular and Cellular Biology SB RAS Novosibirsk Russia

Prague Zoological Garden Prague Czech Republic

School of Biological Sciences Georgia Institute of Technology Atlanta GA USA

Zoo Atlanta Atlanta GA USA

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Nat Rev Genet. 2019 Oct;20(10):564-565. doi: 10.1038/s41576-019-0168-5. PubMed

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Sex chromosome evolution among amniotes: is the origin of sex chromosomes non-random?

A brief review of vertebrate sex evolution with a pledge for integrative research: towards 'sexomics'

Cytogenetic Evidence for Sex Chromosomes and Karyotype Evolution in Anguimorphan Lizards