Don't you phoget about me

The Weddell seal (Leptonychotes weddellii) is a true seal and one of the largest members of the Phocidae family, with adults measuring 2.5 to 3.5 m (8 ft 2 in–11 ft 6 in) in length and weighing from 400 to 600 kg (880–1,320 lb). The species has a circumpolar distribution around Antarctica. Unlike the three other Antarctic seal species (leopard, crabeater, and Ross seals) that inhabit the broken and circulating pack ice extending northward from the continent into the southern ocean, Weddell seals are associated with the fast ice frozen to the continent. They are predators near the top of the food chain and are exceptional divers, capable of holding their breath for up to an hour and diving to depths up to 600 m. Their primary prey are the herring-like Antarctic silverfish, the large Antarctic toothfish, cephalopods, and a variety of smaller fishes. Leopard seals prey on their pups as do Orcas that also prey on adults.

Photo of Weddell seals courtesy of William A. Link, U.S. Geological Survey Patuxent Wildlife Research Center (used with permission).

During the Austral spring, Weddell seals are found in colonies hauled out on the ice in localized areas where cracks due to tides and glacier pressures provide ready access to the ice surface. The females give birth to a single pup and closely attend the pup, with nursing lasting for 30-40 days. Mothers feed very little, if at all, while nursing and lose up to 40% of their body mass. Pups are actively encouraged by mothers to enter the water, with most pups beginning to swim at 10-12 days of age. During the pup-rearing period, adult males establish underwater territories associated with the colonies and compete aggressively to breed females when they become receptive at about the time pups are weaned. Copulation occurs underwater. Maximum life span is approximately 30 years.

Weddell seals are docile when hauled out on the sea ice, with no fear of man, and were exploited for food and fuel during the era of exploration in the late 1800s and early 1900s, with local populations depleted in areas where expeditions were concentrated. All Antarctic seals are currently protected by the international Antarctic Treaty (1961) and the Convention for the Conservation of Antarctic Seals (1978). Weddell seals are the most studied of the Antarctic seal species due to their mild temperament and because researchers have ready access to the animals when the seals are hauled out on the fast ice. The species is considered secure, but there is no reliable estimate of their abundance. Because Weddell seals are closely associated with sea ice and their primary prey are ice-obligates there is concern that global climate change may impact the distribution and abundance of the species in the future. The recent development of commercial fisheries in some portions of the seal’s range also has the potential to impact food resources.

Today, we release the genome assembly for the Weddell seal, Leptonychotes weddellii! The sample used for this experiment was provided by Robert Garrott, Montana State University. Field work for the project was supported by the National Science Foundation, Division of Polar Programs under grant numbers ANT 1141326 and ANT 1640481 to Jay J. Rotella, Robert A. Garrott, and Donald B. Siniff and prior NSF Grants to Robert A. Garrott, Jay J. Rotella, D. B. Siniff, and J. Ward Testa. Browse the 17 chromosomes of the Weddell seal below in the interactive Juicebox.js session below, and visit the assembly page for more data and links.

This is our 7th Phocidae genome assembly, check out the rest here!

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!

The lion king

The lion is a large cat native to Africa and India. Lions have captured our imagination for centuries, from the paleolithic cave art to modern movies and characters in books, lions are at the top of the food chain. The lions have long been associated with kingship, nobility and commanding power. The Swahili word for lion, simba means "king," "strong," and "aggressive", and the sacred "Lion God" in India is a fierce avatar of the Hindu god Vishnu.

Hubert, the lion from the Oklahoma City Zoo who's genome assembly we are sharing today. Photo credit: Andrea Johnson

Did you know that lions are the only cats that live in large social groups? They are called prides. A pride can have from 3 to 30 lions and is made up of lionesses (mothers, sisters, and cousins) and their cubs, along with a few unrelated adult males. The pride has a close bond and is not likely to accept a stranger. Both males and females scent mark to define their territory.

A lion’s life is filled with sleeping, napping, and resting. Over the course of 24 hours, lions have short bursts of intense activity, followed by long bouts of lying around that total up to 21 hours!

Are lions in trouble? It is estimated that there are between 6,000 and 10,000 African lions in Africa. The Asian lion which used to be found across the Middle East and India is represented by only about 500 to 674 individuals, with more than half living in a reserve that used to be royal hunting grounds in an area of dry teak forest called the Gir Forest, now under national protection by the Indian government. The remainder of this particular subspecies lives in zoos.

Due to many issues such as disease, hunting by humans, and loss of habitat, the conservationists are very concerned about the population of lions in Africa. The International Union for Conservation of Nature (IUCN) classifies lions as Vulnerable, but they note that the vast majority of the population is inferred to have declined at a rate that meets the criteria for Endangered. The Asiatic lion currently exists as a single subpopulation in India, and is thus vulnerable to extinction from unpredictable events, such as an epidemic or large forest fire and is fully protected in India.

Today, we share the chromosome-length assembly for the South African lion (Panthera leo krugeri). The assembly was generated from a sample donated by Hubert, the king of the Oklahoma City Zoo lion pride. Thank you to Jennifer D’Agostino, DVM, DACZM, Candice Rennels, Director of Public Relations, Rebecca Snyder, Director of conservation and science and others at the Oklahoma City Zoo for their help with this sample!

This is a $1K de novo genome assembly. See our Methods page for details on the procedure. We gratefully acknowledge the Pawsey Supercomputing Center for the computational support for this assembly, and the computational assistance from the DNA Zoo Australia team at the University of Western Australia. Check the interactive map of Hubert's chromosomes below, and look for more data and info on the assembly page!