The Eastern Water Dragon (Intellagama lesueurii) is one of Australia's largest dragon lizards and can be found living in both natural waterways and within highly developed city centres. Previously Physignathus, Intellagama has only recently been considered its own distinct genus translating to "smart dragon". The specific name lesueurii honours the French naturalist Charles-Alexandre Lesueur (1778-1846) who collected this species on the Baudin expedition of 1800.
Water Dragons are found in eastern Australia, where there are two subspecies. The Eastern subspecies (Intellagama lesueurii lesueurii), occurs along the east coast of Australia from Cooktown in the north down to the New South Wales south coast (approximately at Kangaroo Valley) where it is replaced with the Gippsland subspecies (Intellagama lesueurii howittii), which is distributed as far south and into the Gippsland region of eastern Victoria.
Water Dragons are a charismatic species that can live in large social groups often communicating through a variety of dominant and submissive signals including head-bobbing, arm waving and push-ups. The Water Dragon is a familiar sight in Australian cities and urban areas, where they have become habituated in parks and botanical gardens. Several inner-city populations narrowly separated by urban landscape have begun to diverge from one another, becoming genetically and morphologically distinct. These city slicker dragons have demonstrated that under some circumstance’s evolution can proceed at a significantly faster pace that initially thought.
Although not listed as threatened, Water Dragons are protected in all states and territories where they occur naturally: Queensland, New South Wales, Australian Capital Territory and Victoria.
Today, we share the chromosome-length assembly for the Eastern Water Dragon. DNA Zoo has been working with Associate Prof Celine Frere, Dr Dan Powell and Nicola Kent at The University of Sunshine Coast, Australia to deliver this much required key fundamental genomic resource.
The assembly is based on a draft hybrid assembly effort supported by The Australian Amphibian and Reptile Genomics Initiative (AusARG), a collaborative at Bioplatforms Australia framework initiative building genomic resources for thorough understanding of evolution and conservation of Australia’s unique native Amphibians and Reptiles that are now under threat, through climate, disease or habitat modification. The draft genome assembly was created using high-fidelity long reads from Pacific Biosciences technology (circular consensus sequencing). The reads were assembled using the long-read assembler Hifiasm (Cheng et al., 2021).
The above draft was scaffolded with 118,960,506 PE Hi-C reads generated by DNA Zoo labs using 3D-DNA (Dudchenko et al., 2017) and Juicebox Assembly Tools (Dudchenko et al., 2018). See our Methods page for more details!
The Hi-C work was supported by resources provided by DNA Zoo Australia, The University of Western Australia (UWA) and DNA Zoo, Aiden Lab at Baylor College of Medicine (BCM) with additional computational resources and support from the Pawsey Supercomputing Centre with funding from the Australian Government and the Government of Western Australia.
The new genomic tools and resources for the Eastern Water Dragon (Intellagama lesueurii) will enable detailed investigations into their unique ability to adapt to life in our highly urbanised cities and facilitate a better understanding of how reptiles can respond to rapid environmental change.
The following people contributed to the Hi-C chromosome-length upgrade of the draft assembly: Erez Aiden, Olga Dudchenko, Ashling Charles & Parwinder Kaur.
Blog by: Parwinder Kaur, Nicola Kent, Dan Powell and Celine Frere.
Citations:
Cheng, H., Concepcion, G.T., Feng, X., Zhang, H., Li H. Haplotype-resolved de novo assembly using phased assembly graphs with hifiasm. Nat Methods 18, 170–175 (2021). https://doi.org/10.1038/s41592-020-01056-5