Mutation accumulation in a hybrid parthenogenetic vertebrate.

Asexual Aspidoscelis tesselatus lineages accumulate deleterious mutations at higher rates than their sexual ancestors, supporting Muller's ratchet predictions.

• Why it matters: Understanding how asexual reproduction influences genetic health is crucial, as it may explain the higher extinction risk of asexual lineages and inform conservation strategies.
• What they did: Researchers combined short-read RNAseq and long-read IsoSeq data from both asexual and parental sexual species to reconstruct phased transcripts and compare mutation accumulation across genomes.
• The result: Findings show elevated nonsynonymous mutations and structural variants in the asexual lineage, especially in genes related to core cellular functions, indicating mutation buildup consistent with Muller's ratchet.