No sex for nematodes leads to loss of genes

Nematodes, or roundworms, that undergo asexual reproduction, have only two-thirds as many active genes as related species that reproduce sexually.

Researchers discovered this by comparing the genomes of the hermaphrodite nematodes with species that have male and female sexes.

While, the hermaphrodite nematodes have lost thousands of different genes, genes associated with being male or female and reproduction are especially likely to be lost.

This may be why self-fertilising species have the tendency to go extinct faster than those that undergo sexual reproduction.