All articles tagged with #mullers ratchet
An all-female Amazon molly has thrived for about 100,000 years without males, thanks to gene conversion—a copy-and-paste DNA repair that helps limit harmful mutations—and its hybrid origin gives it genetic variation from the start, suggesting alternative routes to genome health beyond sex.
A 20-year experiment cloning over 1,200 mice across 58 generations shows that deleterious genetic mutations accumulate in cloned lineages, with the 58th generation dying shortly after birth. Initial generations appeared healthy, but the line ultimately collapsed, confirming that mammalian cloning cannot sustain long-term viability and that sexual reproduction is essential for species survival; researchers call for advances in nuclear transfer techniques.
A Japanese team conducted a serial cloning study starting from one female mouse, re-cloning for 57 generations and producing over 1,200 offspring. By generation 58, accumulated genetic mutations and loss of the X chromosome caused the re-cloned mice to die shortly after birth, effectively ending the line. Crossbreeding later-generation clones with normal mice showed initially normal litter sizes but reduced fertility in later-generation lines, with partial recovery in descendants. The results support Muller's ratchet and reinforce the idea that sexual reproduction is essential for long-term mammalian survival, limiting the practical viability of endless cloning.
Researchers show that the clonal Amazon molly uses gene conversion to sustain natural selection: it creates new clonal lineages by reverting or fixing mutations and resolves incompatibilities between parental haplotypes, slowing degenerative mutation accumulation (Muller’s ratchet) while preserving parental divergence and altering chromatin organization in the transition to clonality.