Bioenergetics of parental investment in two polychaete species with contrasting reproductive strategies: The planktotrophicBoccardia chilensisand the poecilogonicBoccardia wellingtonensis(Spionidae)

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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 wormBoccardia wellingtonensisencapsulates and incubates its offspring, which then hatches as either planktotrophic larvae or benthic juveniles; whileBoccardia chilensisshows 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 ofB. wellingtonensisandB. chilensisto 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 ofB. wellingtonensis; but also contained significantly more glucose, protein, and lipid than females ofB. 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.

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