Bioenergetics of parental investment in two polychaete species with contrasting reproductive strategies: The planktotrophic Boccardia chilensis and the poecilogonic Boccardia wellingtonensis (Spionidae)

Abstract

The level of parental investment for larval nutrition may determine the life cycle in marine invertebrate species laying egg masses or capsules, where the food available for enclosed individuals would determine time and developmental stage of hatching. Most species show a unique type of larval development. However, few species are poecilogonous and combine more than one development type. Poecilogony, although scarcely studied, allows comparing different patterns of parental reproductive investment, without the phylogenetic effect of the species ancestral modes of development (phylogenetic inertia), to help to understand the factors determining life strategy evolution in marine invertebrates. The poecilogonous polychaete worm Boccardia wellingtonensis encapsulates and incubates its offspring, which then hatches as either planktotrophic larvae or benthic juveniles; while Boccardia chilensis shows a non‐poecilogonous reproductive type, producing only planktotrophic larvae. In this work, we estimated the bioenergetic and biochemical composition of brooding and non‐brooding females of B. wellingtonensis and B. chilensis to compare the costs of reproduction in these two species. Results showed that glucose, protein, lipid, and energy content were significantly higher in non‐brooding than in brooding females of B. wellingtonensis; but also contained significantly more glucose, protein, and lipid than females of B. chilensis (in absolute and relative dry weight values). The poecilogonous species showed higher energy content previous to laying offspring. Our results support the idea that the evolution of a certain reproductive and life history traits in marine invertebrates is related to adaptations in the female's reproductive investment.

Long term environmental variability modulates the epigenetics of maternal traits of kelp crabs in the coast of Chile

“…Whether the parental environment or the environmental conditions directly experienced by early eggs are responsible for triggering such epigenetic-mediated increase in lipid storage, was outside the scope of this study. Nonetheless, given that stored lipids in early eggs are associated with the maternal investment 34 , the parental environment likely played an important role in shaping offspring reserves through DNA methylation, strongly supporting the idea that epigenetic mechanisms are associated with heritable plasticity in invertebrates 6 . The non-linear positive relationship between DNA methylation diversity and plasticity in egg volume and brood dry weight also suggests, and possibly in a more evident way, that maternal effects, plasticity, and epigenetics are closely linked.…”

“…We chose the volume and the weight of early deposited eggs because they best represent the environmentally induced maternal investment in offspring 33 . Furthermore, we selected neutral lipids as proxy of maternal provisioning in term of bioenergetic reserve 20 , 34 . The epigenetic diversity of eggs was expected to positively relate to the phenotypic variability of traits associated with the maternal investment within each population, confirming the key role of DNA methylation on generating phenotypic variability during gametogenesis and development.…”