Asexual worms solve evolution's genetic puzzle with unusual inheritance
Scientists discovered that some asexual animals maintain genetic diversity through an unexpected mating mechanism—recombinant chromosomes stick together instead of separating. The finding reshapes understanding of how organisms without sexual reproduction survive evolutionary pressures, with implications for genetic engineering, agriculture, and disease control in organisms that reproduce without mates.
Originaltitel: Cosegregation of recombinant chromatids maintains genome-wide heterozygosity in an asexual nematode
<p>In asexual animals, female meiosis is modified to produce diploid oocytes. If meiosis still involves recombination, this is expected to lead to a rapid loss of heterozygosity, with adverse effects on fitness. Many asexuals, however, have a heterozygous genome, the underlying mechanisms being most often unknown. Cytological and population genomic analyses in the nematode Mesorhabditis belari revealed another case of recombining asexual being highly heterozygous genome-wide. We demonstrated that heterozygosity is maintained despite recombination because the recombinant chromatids of each chromosome pair cosegregate during the unique meiotic division. A theoretical model confirmed that this segregation bias is necessary to account for the observed pattern and likely to evolve under a wide range of conditions. Our study uncovers an unexpected type of non-Mendelian genetic inheritance involving cosegregation of recombinant chromatids.</p>