Despite odds, fish species that bypasses sexual reproduction is thriving

Washington University School of Medicine –

The very rare animals that reproduce asexually — only about one in 1,000 of all living vertebrate species — are thought to be at an evolutionary disadvantage compared with their sexually reproduced counterparts. But that theory doesn’t hold true regarding the Amazon molly, an all-female fish species that has thrived for millennia in the fresh waters along the Mexico-Texas border.

To better understand how this fish’s reproduction deviates from the norm, an international team of scientists has sequenced the first Amazon molly genome and the genomes of the original parental species that created this unique fish. Their findings suggest that the molly’s thriving existence is not totally unexpected since they found the fish has a hardy genetic makeup that is often rare in nature and gives the animals some predicted survival benefits.

“It appears the stars aligned for this species,” said first author Wesley C. Warren, PhD, an assistant director at the McDonnell Genome Instituteat Washington University School of Medicine in St. Louis. “The hybridization of two different species’ genomes into one new one would require nearly perfect compatibility between the elements of those parent genomes to bypass the sexual reproduction practiced by most vertebrate species.”

The findings are published Feb. 12 in the journal Nature Ecology & Evolution.

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