Termite colonies are families – millions of individual workers all descended from one king and one queen. But the colony itself tends to outlast this initial royal couple. When they die, new kings and queens rise to take their place. These secondary royals are a common feature of some families of termites, and they will often mate with each other for many generations. But there is more to this system than meets the eye.
Kenji Matsuura from Okayama University has found that the secondary queens are all genetically identical clones of the original. There are many copies, and they have no father – they developed from unfertilised eggs laid by the first queen through a process called parthenogenesis. These clones then mate with the king to produce the rest of the colony through normal sexual means.
It’s a fiendishly clever strategy. The original queen’s legacy to the colony is… herself. She effectively splits herself into several different bodies and in doing so, greatly increases the number of offspring she has. And because each of these descendants mates with the king, who has no genes in common with them, the colony neatly skirts around the problems of inbreeding.
Many animals have cunning ways of hiding from predators. But the larva of the sand dollar takes that to an extreme – it avoids being spotted by splitting itself into two identical clones.
Sand dollars are members of a group of animals called echinoderms, that include sea urchins and starfish. An adult sand dollar (Dendraster excentricus) is a flat, round disc that lives a sedate life on the sea floor. Its larva, also known as a pluteus, is very different, a small, six-armed creature that floats freely among the ocean’s plankton.
A pluteus can’t swim quickly, so there is no escape for one if it is attacked by a hungry fish. Instead, Dawn Vaughan and Richard Strathmann from the University of Washington discovered that the pluteus relies on not being spotted in the first place.
They exposed 4-day-old larvae to water which contained mucus from the skin of a potential predator – the Dover sole. Within 24 hours, every single larva that was exposed to the mucus has grown a small bud that eventually detached and developed into a second larva, genetically identical to its parent and smaller in size. In contrast, larvae that were exposed to untouched seawater stayed undivided.