Abstract: Developmental plasticity can occur at any life stage, but plasticity that acts early in development may give individuals a competitive edge later in life. Here we asked if early (pre-feeding) exposure to a nutrient-rich resource impacts hatchling morphology in Mexican spadefoot toad tadpoles, Spea multiplicata. Induction of a distinctive carnivore morph can occur when a tadpole eats live fairy shrimp. We investigated whether cues from fairy shrimp––detected before individuals are capable of feeding––alter hatchling morphology such that individuals can take advantage of this nutritious resource once they do begin feeding. We found that hatchlings with early developmental exposure to shrimp were larger and had larger jaw muscles––traits that increase their ability to compete for shrimp. Thus, early developmental stages can assess and respond to environmental cues by producing preemptive resource-use phenotypes. Such anticipatory plasticity may be an important but understudied form of developmental plasticity.
