A Fish That Skips Sex and Still Survives: A Genetic Mystery

                 Most species rely on sexual reproduction to mix genes and maintain healthy genetic diversity. However, scientists have discovered a unique fish species that appears to survive without traditional reproduction. The Amazon molly, an all-female fish species, reproduces through a process called gynogenesis. This is where the presence of sperm from a related species triggers reproduction but the sperm’s DNA is not actually incorporated into the offspring.

Normally, species that reproduce without mixing genes are expected to accumulate harmful mutations over time. Without the genetic variation created by sexual reproduction, these mutations can accumulate and eventually threaten the survival of the species. Because of this, scientists once believed that asexual species would not survive for long periods of time.

Recent research has revealed that the Amazon molly may avoid this problem through a genetic process known as gene conversion. Gene conversion is a mechanism where DNA sequences can be copied from one chromosome to another, effectively repairing or replacing damaged genetic information. This process allows the fish to remove some harmful mutations and maintain a relatively healthy genome.

                                 

This discovery is significant because it challenges long-standing ideas about evolution and reproduction. Scientists previously believed that sexual reproduction was essential for long-term survival because it helps prevent the buildup of harmful mutations. However, the Amazon molly has existed for more than 100,000 years, suggesting that alternative genetic mechanisms can help maintain genetic stability.

Understanding how gene conversion works in this species could help scientists learn more about how genomes repair themselves and how evolution can occur in unexpected ways. This research may also provide insights into how genetic mutations are managed in other organisms, including humans.

Source: 

https://www.sciencenews.org/article/sex-skipping-fish-hacks-evolution-gene

Additional Link: 

https://medlineplus.gov/genetics/understanding/mutationsanddisorders/