Bdelloids: No sex for over 40 million years

Talk about a dry spell. Microscopic bdelloid rotifers have seemingly evolved without sex for millions of years and probably don’t exist in male form, say Harvard University biologists.

Four species of bdelloid (meaning leechlike) rotifers, one (top left) eating algae and another (top right) containing an egg. Science

The bdelloid genome shows an odd pattern of differences between versions of the same genes, report David Mark Welch and Matthew Meselson.