Cited research: Proc. R. Soc. B doi:10.1098/rspb.2010.0877 (2010)

Exposure of ancient tadpoles to novel foodstuffs may have awoken genetic variation previously hidden from natural selection, leading to the evolution of new eating habits.

Cris Ledón-Rettig of the University of North Carolina at Chapel Hill and her team studied Couch's spadefoot tadpoles (Scaphiopus couchii), which eat algae and other organic material. The authors fed the tadpoles a shrimp diet resembling that eaten by tadpoles of the spadefoot toads (genus Spea), which probably evolved from ancestors similar to S. couchii. After feeding on the shrimps, the S. couchii tadpoles showed greater variation in growth and development speed than controls.

Similar results were seen in tadpoles treated with a hormone that is produced in response to dietary changes, suggesting that hormones may have mediated the Spea tadpoles' transition to carnivory. J.F.