Initial offspring size mediates trade-off between fecundity and longevity in the field

Abstract

An understanding of the effects of intraspecific variation in offspring size is important from both an ecological and an evolutionary perspective. While the relationship between offspring size and overall offspring performance is key, most studies are restricted to examination of the effects of offspring size on early life-history stages only, and too few have examined the effects of offspring size throughout the life history. Here, we examine the effects of offspring size on post-metamorphic survival, growth, and fecundity under field conditions for the polychaete Janua sp. Larger offspring became larger adults and had higher levels of fecundity than those from smaller offspring, though the effect on fecundity was weaker and more variable over different experimental runs. Adults derived from larger larvae had shorter lifespans than adults derived from smaller larvae. Our results suggest that the maternal effect of offspring size can influence the frequently observed trade-off between longevity and fecundity. Future studies should seek to measure the effects of offspring size over as much of the life history as possible in order to avoid misestimating the relationship between offspring size and fitness.