The dragonfly effect

The Black Petaltail (Tanypteryx hageni) is one of eleven dragonfly species in the family Petaluridae. The family’s name recognizes the large, wide claspers at the end of the male abdomen (resembling the petals of a flower), which are used to clasp the female while mating. The Black Petaltail is found in western North America, from British Columbia in Canada to southern California in the US, but other species of petaltail are found in Australia, New Zealand, Chile, eastern North America and Japan. Like other dragonflies petaltails have an aquatic juvenile stage (a larva or nymph), but these are not found in ponds or streams like the majority of dragonfly species; petaltails live in fens and bogs, places near springs and small streams where the soils are consistently saturated with water.

Adult Tanypteryx hageni, courtesy of Carey Kerst, AMNS (used with permission)

Most species of petaltail construct and maintain a burrow in these fens—the ‘Hobbits’ of the dragonfly world, living in a hole in the ground. The burrow fills with water, and the petaltail nymphs live in these burrows for multiple years before emerging as adults—the Black Petaltail is thought to take five years to develop. Black petaltail fens are usually found in mountain valleys, in large meadows surrounded by forests. As such habitats can be quite isolated, and are also subject to increasing risk from wildfires in these areas. Understanding how these dragonflies are adapted to these unique habitats, and how their long development times influence their populations genetics, will be some of the questions that can be addressed with a quality genome assembly.

Today, we share the chromosome-length assembly for the black petaltail (Tanypteryx hageni). The draft assembly was generated by Ethan Tolman, Paul Frandsen, Jessica Ware, Christopher Beatty and colleagues at the American Museum of Natural History colleagues at the American Museum of Natural History. Data from two PacBio Sequel II SMRT cells generated at the BYU sequencing center was assembled with Hifiasm (Cheng et al., 2021). We upgraded the draft to chromosome-length using Hi-C data from a hemolymph sample from a juvenile petaltail not unlike the one you can see in the photo below, collected by Christopher Beatty in 2022 in the Lassen National Forest in California.

Juvenile nymph Tanypteryx hageni courtesy of Christopher Beatty (AMNS)

Funding for this project was provided by the College Undergraduate Research Award from the College of Life Sciences at Brigham Young University. We are also grateful for Grant #8709-09 from the National Geographic Society Committee for Research and Exploration.

We are also very proud to announce that Chirag Maheshwari, the DNA Zoo team member who helped bring this genome assembly to it's chromosome-length glory, has just been awarded the Atlas Fellowship for outstanding high school students. Congratulations!

Check out the interactive Juicebox.js instance below for a contact map of the 9 chromosomes of T. hageni. And don't forget to visit the assembly page for more info and links!