The Oldest Parental Split Of Any Animal, Plant, Or Fungi Hybrid Is A Fish

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

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

“The hybrids resemble the body of a large Longnose Gar, just 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 (right).
Images credit: Kati Wright

Project collaborator and Alligator Gar expert Dan Daugherty of Texas Parks & Wildlife told Wright that hybrids are caught here around 1-2 percent of the time, making this a “rare and exciting” catch. It wasn’t the fish’s first rodeo, mind, having already been caught and tagged for a different study.

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

“I’ve 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, look like something completely new, with the almost dalmatian black and white blotches.” 

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

The ancient splits of the Alligator Gar x Longnose Gar demonstrates the slow rate of evolution seen among gars – a group of primitive fishes David says are often wrongfully considered “trash fish”, and yet we stand to learn so much from them. It’s thought they may have super-efficient DNA repair that could explain the low species diversity, and if so, could inform research into human health and cancer.

Getting there involves transgenic and toxicological experiments of other vertebrates and gars, but by all accounts, working with these animals makes for an exhilarating job, 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.
Image credit: Kati Wright

“One time GarLab was fishing with U.S. Fish and Wildlife Service for Alligator Gar,” said Wright. “We pulled in a gillnet with seven 7-foot [2.1-meter], 140-pound [64-kilogram] Alligator Gars and one Longnose Gar into this tiny jon boat with four people in it! I thought, ‘We really are gonna need a bigger boat.’”

“I was on the shore as their boat approached, filled with GARgantuan Alligator Gars,” added David. “It was an awesome sight. Luckily gars breathe air, so they were just fine as our team quickly processed them (measured, tagged, and released). They don’t really make boat livewells the size of Alligator Gars!”

Move aside, Snakes On A Plane, we want to see Gars On A Boat.

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