The oldest parental separation of all hybrid animals, plants or fungi is a fish

Recently the big news came out that the genetic history of Gars reveals that they are ‘living fossils’, evolving significantly slower than any other jawed vertebrate. The breakthrough in our understanding of living fossils revealed why they have remained largely unchanged for tens of millions of years, and it means they can create viable hybrids with other species – even if they haven’t shared a common ancestor since dinosaurs walked the Earth. .

Hybrids discovered between the Alligator Gar and Longnose Gar represent the descendants of genetically isolated groups whose last common ancestor existed 100 million years ago, making it the oldest identified parental division among animals, plants and fungi. These hybrids are rare, but not unheard of. By sweet serendipity, one of co-author Solomon David’s graduate students – Kati Wright of Nicholls State University – actually discovered one the same week as the living fossil paper’s publication.

“The hybrids resemble the body of a large Longnose Gar, only with a wider snout,” Wright explained to IFLScience. “Their ganoid scales even look different from Alligator Gar.”

An alligator gar (left) and the hybrid Alligator Gar x Longnose Gar.

An Alligator Gar (left) and the hybrid Alligator Gar x Longnose Gar (right).

Images credit: Kati Wright

Project officer and Alligator Gar expert Dan Daugherty of Texas Parks & Wildlife told Wright that hybrids are caught here about 1 to 2 percent of the time, making this a “rare and exciting” catch. It wasn’t the fish’s first rodeo, as it had already been captured and tagged for another study.

Wright is a member of GarLab, which moved to the University of Minnesota with David, the lab’s principal investigator, and has extensive experience working with gars in captivity.

“I have handled and cared for other gar hybrids in aquariums,” he told IFLScience. “Their patterns can be a stunning combination of the parent species, and in some cases, like the Spotted x Alligator Gar, they look like something completely new, with the almost Dalmatian black and white spots.”

“The Alligator Gar ‘side of the family’ appears to be expressed in aquarium individuals, with the hybrids being somewhat aggressive. Shortnose x Alligator Gar hybrids tend to have the aggression of the Alligator Gars along with the more skittish nature of Shortnose Gars. Morphologically, they show intermediate characteristics of the parents, especially in their snout.”

The ancient splits of Alligator Gar and Longnose Gar demonstrate the slow evolution we see in gars – a group of primitive fish that David says are often wrongly regarded as ‘garbage fish’, and yet we can learn so much from them. They are thought to have super-efficient DNA repair that could explain the low species diversity, and if so, it could inform research into human health and cancer.

Getting there will require transgenic and toxicology experiments with other vertebrates and gars, but by all accounts, working with these animals is exciting, if not a little. Jaws‘ish.

Photo shows Hybrid Alligator Gar x Longnose Gar above, Alligator Gar below for comparison.  Inset shows the profile of hybrid gar.

Photo shows Hybrid Alligator Gar x Longnose Gar above, Alligator Gar below for comparison. Inset shows the profile of hybrid gar.

Image credit: Kati Wright

“One time, GarLab was fishing for Alligator Gar with the U.S. Fish and Wildlife Service,” says Wright. “We hauled in a gillnet with seven 7-foot ones [2.1-meter]140 pounds [64-kilogram] Alligator Gars and a Longnose Gars in this small jon boat with four people in it! I thought, ‘We really need a bigger boat.’”

“I was at the shore when their boat approached, filled with GARgantuan Alligator Gars,” David added. “It was an amazing sight. Luckily, gars breathe air, so they did just fine as our team quickly processed (measured, tagged, and released) them. They don’t really make boat life sources as big as Alligator Gars!”

Move aside, Snakes in a planewe want to see Gars on a boat.

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