title: Egg size effects across multiple life-history stages in the marine annelid Hydroides diramphus.
abstract: The optimal balance of reproductive effort between offspring size and number depends on the fitness of offspring size in a particular environment. The variable environments offspring experience, both among and within life-history stages, are likely to alter the offspring size/fitness relationship and favor different offspring sizes. Hence, the many environments experienced throughout complex life-histories present mothers with a significant challenge to optimally allocate their reproductive effort. In a marine annelid, we tested the relationship between egg size and performance across multiple life-history stages, including: fertilization, larval development, and post-metamorphosis survival and size in the field. We found evidence of conflicting effects of egg size on performance: larger eggs had higher fertilization under sperm-limited conditions, were slightly faster to develop pre-feeding, and were larger post-metamorphosis; however, smaller eggs had higher fertilization when sperm was abundant, and faster planktonic development; and egg size did not affect post-metamorphic survival. The results indicate that egg size effects are conflicting in H. diramphus depending on the environments within and among life-history stages. We suggest that offspring size in this species may be a compromise between the overall costs and benefits of egg sizes in each stage and that performance in any one stage is not maximized.
authors.affiliation: School of Biological Sciences, University of Queensland, St Lucia, Queensland, Australia.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Allen
authors.affiliation: School of Biological Sciences, University of Queensland, St Lucia, Queensland, Australia.
authors.forename: Dustin
authors.initials: D
authors.lastname: Marshall
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000254:growth & development*; D049628:Body Size; D005260:Female; D007814:Larva / Q000254:growth & development; D008018:Life Cycle Stages; D008297:Male; D009035:Mothers; D010063:Ovum / Q000254:growth & development*; D011077:Polychaeta / Q000254:growth & development*