Does total reproductive effort evolve independently of offspring size?

In all species, patterns of reproductive allocation have important fitness consequences and therefore important implications for life-history evolutio n. Nearly universally, theory in this field has modeled as independent the evolution of total allocation to offspring and the subsequent division of t his allocation into many small versus few large offspring. Yet, some theory and a very small amount of experimental evidence suggest that these life-h istory traits may be evolutionarily linked. Using comparative analyses of c opepod life histories, we illustrate that rather than being evolutionarily independent these traits can be linked, in this case, across a very large c lade of invertebrates. Our results indicate that a more complete understand ing of the evolution of these traits will require greater consideration of simultaneous allocation decisions, rather than sequential ones, and other g enetic and selective mechanisms.