![]() ![]() To understand the genetic underpinnings of Komodo dragon physiology, we sequenced its genome and present a de novo assembly, generated with a hybrid approach of Illumina short-read sequencing with long-range sequencing using 10x Genomics, PacBio and Oxford Nanopore sequencing, and single-molecule optical mapping using the Bionano platform. Furthermore, Komodo dragons engage in aggressive intraspecific conflicts over mating, territory and food, and wild individuals often bear scars from previous conflicts 4. Their ability to locate injured or dead prey through scent tracking over several kilometres is enabled by a powerful olfactory system 4, and their hunting is aided by serrate teeth, sharp claws, and saliva with anticoagulant and shock-inducing properties 7, 8. Komodo dragons have a higher metabolism than predicted by allometric scaling relationships for varanid lizards 5, which may explain their capacity for daily movement to locate prey 6. The largest of the varanid lizards, the Komodo dragon Varanus komodoensis, can grow to 3 m in length and run up to 20 km h −1, allowing them to hunt large prey including deer and boar 4. Furthermore, varanid lizards can achieve and sustain higher aerobic metabolic rates and endurance capacity than similar size non-varanid squamates, which enables intense, sustainable movements while hunting prey or in bouts of male–male combat. This enables a dual-pressure cardiovascular system characterized by high systemic and low pulmonary blood pressures 3. For example, their cardiac anatomy is characterized by well-developed ventricular septa (‘muscular ridge’ and ‘bulbus lamellae’) resulting in a functionally divided heart 3. Varanids have a unique cardiopulmonary physiology and metabolism with numerous parallels to the mammalian cardiovascular system. Varanids exhibit the largest range in size among reptiles, varying in mass by over five orders of magnitude (8 g–100 kg) 2. The varanid lizards (genus Varanus, or monitor lizards) are an unusual group within squamate reptiles (lizards and snakes). Understanding how these adaptations evolved through changes to biochemical and cellular processes will reveal fundamental insights into areas ranging from anatomy and metabolism to behaviour and ecology. There are an estimated 10,000 reptile species worldwide, found on every continent except Antarctica, with a diversity of lifestyles and morphologies 1 corresponding to a broad range of anatomic and physiological adaptations. The evolution of form and function in non-avian reptiles contains numerous examples of innovation and diversity. The Komodo dragon genome is an important resource for understanding the biology of monitor lizards and reptiles worldwide. 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. We also show species-specific expansions of a chemoreceptor gene family related to pheromone and kairomone sensing in V. komodoensis with those of related species, we find evidence of positive selection in pathways related to energy metabolism, cardiovascular homoeostasis, and haemostasis. komodoensis using a hybrid approach of long-range sequencing and single-molecule optical mapping. 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. Monitor lizards are unique among ectothermic reptiles in that they have high aerobic capacity and distinctive cardiovascular physiology resembling that of endothermic mammals. Nature Ecology & Evolution volume 3, pages 1241–1252 ( 2019) Cite this article Genome of the Komodo dragon reveals adaptations in the cardiovascular and chemosensory systems of monitor lizards ![]()
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