Reproduction strategy of nocturnal marine molluscs:running for love

The cost of reproduction is the core driver of life history evolution in animals.This paper demonstrates that the cumulative distance moved and the duration of movement of sexually immature abalones,Haliotis discus hannai,kept in various male and female groups,were significantly higher than those of sexually mature individuals,except when kept in mixed cultures of mature males and females.After mixed-culture,sexually mature males moved significantly further and for a longer duration than mature female abalones,and even more so than mature male abalones of any other group.Examination of the LC-MS metabolomics of mature males cultured with sexually mature females(AM)and those cultured with sexually immature females(JM)showed that cyclic adenosine monophosphate(cAMP)acted as a differential metabolic biomarker.After 24-h uninterrupted sampling,the concentration of 5-HT and the expression levels of the 5-HT2 and 5-HT6 receptors in AM were significantly higher than those in JM.After further injection of 5-HT2 and 5-HT6 receptor antagonists,the concentrations of cAMP and PKA rose again,but the cumulative movement duration and distance of male abalones decreased significantly,showing that 5-HT was involved in the regulation of movement behavior of male abalones through the 5-HT2 and 5-HT6 receptor-activated cAMP-PKA pathways.The results demonstrated a significant increase in the movement endurance of mature male abalones cultured with mature females,providing a theoretical basis for understanding the adaptive life history strategies of abalones and suggesting ways to protect diverse benthic resources for abalones during the reproductive stage.

Seemingly maladaptive refraining from infanticidal probing at the third parasitism attack by the semi-solitary parasitoid Echthrodelphax fairchildii （Hymenoptera： Dryinidae）

We assessed the adaptiveness of refraining from infanticidal probing at the third attack under triple parasitism in the parasitoid Echthrodelphaxfairchildii Perkins, by comparing fitness returns from the third attack with and without probing. Fitness returns were assessed in terms of the survival rate, mean developmental time, and mean adult head width of the progenies. Not probing was maladaptive under triple parasitism with oviposition intervals of 1/24 and 24/24 hours （where the numbers before and after the slash refer to the first-to-second and second-to-third oviposition intervals, respectively）, although no significant difference was detected in fitness returns for oviposition intervals of 24/1 hours. We suggest that the cost of probing （especially the decrease in the chance of future ovipositions） is a reason for the seemingly maladaptive absence of probing.

Sexual dimorphism in water and nitrogen use strategies in Honckenya peploides: timing matters

Aims Sexes of dimorphic species often differ in ecophysiological traits and display spatial segregation.These differences have been interpreted as an evolved response of the sexes to meet the specific resource demands associated with reproduction.Sexes may differ not only in the amount of resources allocated to reproduction but also in the tim-ing of allocation to reproduction.In this study,we hypothesize that as a consequence of their specific resource demands for reproduction,the sexes of the dune plant Honckenya peploides differ in terms of tempo-ral patterns of water use efficiency and nitrogen use and acquisition.Methods Water use efficiency,as inferred from leaf carbon isotope discrimi-nation(Δ^(13)C),nitrogen use,estimated by leaf nitrogen isotope com-position(δ^(15)N),and the foliar carbon and nitrogen contents were measured in males and females at three different points in time.Important Findings Females had greater water use efficiency than males,regardless of time.The ratio of N^(15) to N^(14) did not change with time in males,but significantly decreased in August for females.The total N content in the leaf tissues of females decreased as the season progressed,while in males a decrease was only found from April to June and then it remained constant from June to August.A similar pattern,but reversed,was followed by the foliar C/N ratio.Additionally,nega-tive relationships between leafΔ^(13)C and N content were found at all times for males and only at the end of the season for females.Thus,our hypothesis that sex-specific patterns of nitrogen and water use efficiency will depend on time was supported.Overall,our results highlight the importance of including time in studies of sex-ual dimorphism,and also the role that physiological specialization plays in meeting the specific demands associated with reproduction.