Same genes, different body: the making of a queen

English: Biston betularia caterpillars on birc...
An example of polyphenism: Biston betularia caterpillars on birch (left) and willow (right). (Photo credit: Wikipedia)

How tall are you? Almost everyone I know (myself being an exception) is taller than their same-sex parent, who is, in turn, taller than their same-sex parent. Over recent generations, average height has increased in many parts of the world. This is far too quick to put it down to an evolutionary change based on shifting genetics. Most of us are taller than our parents and grandparents because of our environment — better nutrition, fewer diseases, and less hard labour in our developing years.

But if you really want to see what environmental cues can do to body shape and function, consider the case of social insects. The environment in which a larva is nurtured determines whether it goes on to be a queen or a worker. The caste system of insects is an example of a phenomenon called polyphenism, where the same set of genes (genotype) can result in vastly different body forms (phenotypes). Unlike height in humans, which varies along a continuum, polyphenism in insects creates discrete types. There’s no half-way point between worker and queen; you’re either one or the other. In the one case, you are bound for reproductive glory, in the other, you remain sterile.  Continue reading “Same genes, different body: the making of a queen”