Genetic Basis Found for Redback Spider's Mating Death Somersault

A study in Biology Letters traced the male redback spider's "self-sacrificial somersault" — flipping into the female's jaws during mating — to a likely sex-chromosome-linked genetic basis. Researchers bred redbacks with the closely related New Zealand katipō, which lacks the behavior. Close to half of third-generation hybrids somersaulted, consistent with sex-chromosome inheritance rather than a complex polygenic mechanism.