Transgenerational induction of defences in animals and plants

Predators are potent agents of natural selection in biological communities. Experimental studies have shown that the introduction of predators can cause rapid evolution of defensive morphologies and behaviours in prey(1-5) and chemical defences in plants(6,7). Such defences may be constitutively expressed (phenotypically fixed) or induced when predators initially attacks(8-10). Here we show that non-lethal exposure of an animal to carnivores, and a plant to a herbivore, not only induces a defence, but causes the attacked organisms to produce offspring that are better defended than offspring from unthreatened parents. This transgenerational effect, referred to as a maternally induced defence, is in contrast to the more common defences induced in single individuals within a generation. Transgenerational induction of defences is a new level of phenotypic plasticity across generations that may be an important component of predator-prey interactions.