A surprise fertilization in a fish nursery has led to the creation of a new hybrid fish from two species that are farther apart on the evolutionary tree than humans and mice. Scientists were trying to save the Russian sturgeon from extinction and instead accidentally crossed it with another species creating this strange mix.
Thus, the sperm of an American paddlefish was able to fertilize the eggs of a Russian sturgeon to create a hybrid group of animals never seen before . Formed by the gametes of seven individuals, the group that was born exhibited different proportions of characteristics of the two species, and survival rates beyond 30 days that ranged from 62% to 74%.
Both animals represent two of the largest and longest-lived fish species in the world, with an ancient divergence of the evolutionary tree that makes them living fossils. They exist in different parts of the planet and shared a common ancestor when dinosaurs were still walking the Earth, leading researchers to believe that they were too far from the evolutionary tree to be hybridized. But apparently … no.
“I just didn’t believe it. I thought, hybridization between sturgeon and paddlefish? There’s no way,” the authors explain in Genes magazine.
The accident occurred when scientists at the Hungarian Fisheries and Aquaculture Research Institute were trying to determine whether the introduction of asexual reproduction in paddlefish and sturgeon could protect their population numbers, which are plummeting in the face of overfishing, pollution and habitat loss. Regardless, the resulting offspring seem to be surviving.
The researchers emphasize that it was never their intention that the two species were combined . Like many other hybrids in nature, these offspring are sterile.
Reference: Jenő Káldy et al. Hybridization of Russian Sturgeon (Acipenser gueldenstaedtii, Brandt and Ratzeberg, 1833) and American Paddlefish (Polyodon spathula, Walbaum 1792) and Evaluation of Their Progeny, Genes (2020). DOI: 10.3390 / genes11070753
