“A parent-offspring trade-off limits the evolution of an ontogenetic niche shift”

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Hanna ten Brink and André de Roos

Why do most animal species shift niche during life? Evolution is limited by a trade-off between juveniles and adults

Almost all animal species, including fish, insects, amphibians and reptiles, change their diets as they grow larger. Even though these changes in diet are very common, it is not well understood why this strategy has evolved in the animal kingdom. Ten Brink and de Roos use computer simulations to study the evolution of diet shifting. They show that switching diets might induce the evolution of metamorphosis, where there is an abrupt change in morphology from the larval to the juvenile stage.

While it can be advantageous for individuals to change their diet at one point, there is also a downside to this strategy. A morphology that allows the individual to feed on a certain food type is not necessarily useful when feeding on a different food type. Species that feed upon different food types over the course of their lives therefore face a trade-off. They can either specialize on the food they eat early in life or on the food they eat later in life.

Ten Brink and de Roos show that it is beneficial for large individuals to change diet when this increases the food intake of the switching individuals. However, it is not possible to specialize on the food used later in life when this requires a morphology from birth which reduces the ability to eat the food used in the earlier life stages. There is therefore strong selection to decouple the different life-stages, for example by evolving a metamorphosis, such that juveniles and adults can evolve independently from each other. Read the Article