How does a clonal fish avoid extinction?

For over 100,000 years, the Amazon molly (Poecilia formosa) has been breaking the rules of evolution. As an all-female, asexually reproducing fish, it should have gone extinct long ago due to the steady accumulation of harmful genetic mutations. Yet, it continues to thrive.

How does it survive without sexual reproduction to weed out bad genes? A groundbreaking study published in Nature, spearheaded by our chair's own Dr. Edward Ricemeyer, has finally solved this evolutionary riddle.

Using cutting-edge, high-resolution genome sequencing, Dr. Ricemeyer and an international research team discovered that the Amazon molly relies on a brilliant survival strategy: a DNA repair mechanism called gene conversion.

"Gene conversion can effectively overwrite harmful mutations with healthy copies of the same gene," Dr. Ricemeyer explains. Instead of passing down degraded DNA, the fish actively repairs its genetic code by using intact, healthy sequences as templates.

This pivotal discovery by Dr. Ricemeyer highlights how natural selection can still function efficiently in clonal lineages. By replacing damaged variants with healthy ones, the Amazon molly achieves the genetic maintenance usually provided by sexual reproduction. We are incredibly proud of Dr. Ricemeyer's vital contribution to this Nature publication, which fundamentally changes our understanding of genomic health across the tree of life!

If you would like to read more about Dr. Ricemeyer's work on Amazon molly you can go to LMU News Room or read the publication here.