Temporal Patterns of Energetic Trade-Offs in the Polyplacophoran Rhyssoplax olivacea (Spengler, 1797) From the Northwestern Aegean Sea (eastern Mediterranean)
摘要
Energetic trade-offs are of vital importance for the performance and fitness of organisms. This biological aspect has been examined for chitons in tropical waters, but remains understudied in temperate systems, where seasonality in oceanographic parameters may impose different constraints on resource allocation. R. olivacea is a common chiton in the Mediterranean Sea, inhabiting wide environmental gradients. Using several indices associated with reproduction, somatic growth and feeding, monthly changes in tissue investment were examined for 384 adult individuals of Rhyssoplax olivacea from the Pagasitikos Gulf, Aegean Sea. Measurements for population density and monthly temperature were also taken. All relationships between tissues and total body morphometrics showed positive allometry, suggesting that adult individuals prioritize development of specific tissues relative to body growth. Results indicate an inverse relationship between gonad production and somatic growth, with resource investment in the radula being lowest during peak gonad production and relative intestinal length showing lowest values immediately before, during, and after the reproductive period. Temperature was positively associated with reproductive allocation, while higher temperatures are also linked to sex-specific differences in the high-metabolic allocation mode, whereas population density had no significant effect on resource allocation. Habitat effects at the microscale level appeared to only affect resource allocation in the foot The present study provides baseline evidence for seasonal tissue-level resource allocation in R. olivacea, revealing temperature-driven reproductive investment and sex-specific energetic strategies.