It’s easy to see how droughts, fires and other features of the environment alter and determine the shape of a forest, from the trees that compose it, to where and which trees grow and live together.

Genes. They’re what control the way living things look and even function, what eye color they may have and even what diseases they may live with. Scientists have worked for decades to understand how some genes get switched on while others are switched off, or silenced, determining which traits are expressed.