Tag Archives: sex

Hot streak: how rising temperatures are skewing some animals’ sex ratios

In the 1993 film Jurassic Park, characters create a theme park populated with cloned dinosaurs that purportedly will not reproduce because they are all female. When the skeptical chaos theorist Dr. Malcolm voices concerns, the park’s lead geneticist Dr. Wu explains, “We control their chromosomes. It’s really not that difficult.” Of course, controlling sex determination—the

Bdelloid Rotifers: Sex,Take 2

Isaac Newton, one of the most famous physicists to have ever existed, lived to be 84 years old and did so under a celibate promise. Imagine a lifetime without sex. Now imagine tens of millions of years without sex: meet the Bdelloid rotifers (Fig 1). These tiny, female-only metazoans (0.5 mm in length) are well-known for their asexuality and resilience toward desiccation and ionizing radiation. And while other animals like komodo dragons, stick-insects (Timema stick-insects have reproduced asexually for over 1 million generations!), and some sharks can asexually reproduce in response to the lack of viable males (in most cases), it’s incredibly rare to see an animal that reproduces asexually exclusively. Bdelloid (pronounced del●loi●d) rotifers are an “evolutionary scandal“, completely challenging the sexual reproduction dogma—that is, introducing genetic variation to allow species to adapt to their dynamic environments in addition to mitigating genetic degradation for the benefit of the population.

Not having sex isn’t what necessarily makes rotifers scandalous (bacteria don’t have sex and look at how well they’re doing), it’s that they’re complex multicellular organisms who have speciated to a degree similar to that of sexually reproducing organisms and who have done so asexually.