Asexuality is not only doomed, it’s contagious
Scientists studying the water flea have discovered that asexual males can spread the asexuality gene to sexual populations—in effect, by a process of contagious asexuality.
“One might think of this process as a transmissible asexual disease,” says Michael Lynch, a biology professor at Indiana University.
Geneticists have long bet on the success of sexual reproduction over asexual reproduction based in a large part on the process known as Muller’s ratchet, the mechanism by which a genome accrues deleterious and irreversible mutations after the host organism has lost its ability to carry out the important gene-shuffling job of recombination.
The new work from Lynch’s team instead indicates that most deleterious DNA sequences contributing to the extinction process are actually present in the sexual ancestors, albeit in recessive form, and simply become exposed via fast-paced gene conversion and deletion processes that eliminate the fit genes from one of the parental chromosomes.
After sequencing the entire genomes of 11 sexual and 11 asexual genotypes of Daphnia pulex, a model organism for the study of reproduction that is more commonly known as the water flea, the team discovered that every asexual genotype shared common combinations of alleles for two different chromosomes transmitted by asexual males without recombination. (via Asexuality is not only doomed, it’s contagious | Futurity)