On optimal propagule size and developmental time

A negative relationship between propagule size and development time is often imposed as a constraint on the evolution of optimal propagule size. Here I argue that when mortality is size-dependent, the optimisation of propagule size is in fact independent of the length of the ensuing developmental period. Furthermore, I show that whether larger or smaller propagules are favoured in response to factors that affect growth and mortality rates will depend on which of these variables scale more sharply with size. I use marine fish to exemplify some of the points raised in this note.