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.

Multi‐generational responses of a marine polychaete to a rapid change in seawater pCO2

“…Egg volume, a proxy for egg quality (Allen and Marshall ), was determined by taking a picture of the second egg mass using the bio‐imaging system. The longest and shortest axes of 10 eggs were then measured using imageJ (http://rsb.info.nih.gov/ij/) and egg volume (expressed as × 10 −3 mm 3 ) calculated using the formula: where A is the short radius and B the long radius (Simonini and Prevedelli ).…”

Life-history trade-offs and limitations associated with phenotypic adaptation under future ocean warming and elevated salinity

“…Body size (defined as the number of chaetigers for each individual) was determined at each reproductive event and subsequently used to identify the maximum body size an individual reached during its lifespan. Egg volume, used as a proxy for egg quality [53], was determined using the second egg mass of each pair. The longest and shortest axes of 10 eggs were measured using IMAGEJ (http://rsb.info.nih.gov/ij/) and egg volume (expressed as Â10 23 mm 3 ) calculated using the formula:…”

Complex offspring size effects: variations across life stages and between species

“…Challenges to this common assumption have previously been reported in terrestrial and aquatic vertebrates (Dibattista et al 2007;Warner and Shine 2007;Maddox and Weatherhead 2008) and in ascidians (Jacobs and Sherrard 2010). While difficulties in interpreting maternal effects and costs/benefits across life stages have been emphasized (Marshall and Uller 2007;Allen and Marshall 2014), size is still commonly viewed as an indicator of offspring quality/fitness in defining strategies adopted by mothers. We show here, in line with a growing number of studies, that this underlying assumption is tenuous, further challenging the current framework under which maternal and offspring effects are examined.…”

“…Offspring size may also influence postmetamorphic performance, including survival, growth, competition among conspecifics, and reproduction of the next generation (Emlet and Hoegh-Guldberg 1997;Emlet and Sadro 2006). Current studies of size-related offspring performance in benthic organisms have most often focused on a single life stage (especially the postmetamorphic stage), whereas limited empirical data exist on size-related fitness across multiple life stages (Moran and Emlet 2001;Marshall et al 2006;Rius et al 2009;Dias and Marshall 2010;Allen and Marshall 2014). In addition, investigations in this field have centered on ascidians and bryozoans (e.g., Keough 2005, 2008;Dias and Marshall 2010;Jacobs and Sherrard 2010), and a few species of echinoderms, molluscs, crustaceans, and annelids (e.g., Emlet and Hoegh-Guldberg 1997;Moran and Emlet 2001;Emlet and Sadro 2006;Allen and Marshall 2014).…”