Instead, females just seem to produce eggs that hatch into more bdelloids without fertilization. Among biologists, bdelloids have been called an evolutionary scandal. Several past claims for asexual species collapsed, recalls sex evolutionist Laurence D. Hurst at the University of Bath in England. If you were a Martian looking around, you'd be pretty sure we were asexual. For a molecular test, Meselson focussed on four bdelloid genes.
Sexual organisms inherit a copy of a gene from each parent.
If two-parent reproduction vanishes, the organism just keeps copying its own genes. Like a fax of a fax of a fax, the genome gets glitches. If they aren't harmful, they build up. One copy of a gene in an ancient asexual can develop very different mistakes from the same organism's other copy. Without sex to spread them around, copies of the same gene within an organism can look as different from each other as if they began diverging when sex stopped.