社群等级对金乌贼行为表型及能量代谢的影响

采用实验生态学方法,在室内水槽条件下研究了金乌贼(Sepia esculenta Hoyle,1885)繁殖过程中社群等级的形成对其行为表型和能量代谢的影响,分析测定了不同优势等级雌雄个体腕部肌肉和性腺组织中己糖激酶(Hexokinase, HK)、丙酮酸激酶(Pyruvate kinase, PK)、乳酸脱氢酶(Lactate dehydrogenase, LDH)、苹果酸脱氢酶(Malate dehydrogenase, MDH)、柠檬酸合酶(Citrate synthetase, CS)活性以及乳酸(Lactic acid, LD)含量。结果显示:(1)金乌贼繁殖期不同优势等级雌雄个体之间行为表型具有显著差异,优势雄性个体游动悬浮、争斗时间显著高于劣势个体,而优势雌性个体静止伏底时间高于劣势个体,游动悬浮时间低于劣势雌性;(2)优势雄性个体在争斗过程中主要通过无氧代谢提供能量,而处于游动悬浮状态时通过有氧代谢提供能量。主要表现在优势雄性个体肌肉中无氧代谢酶(PK、HK、LDH)活性显著高于劣势个体(P0.05),有氧代谢酶(MDH、CS)活性也显著高于劣势个体,雌性个体之间则差异不显著(P0.05);(3)繁殖期雌性个体通过减少运动量来储存能量用于产卵繁殖,主要表现在优势雌性个体肌肉中有氧代谢酶(MDH、CS)活性低于劣势个体,而在性腺中恰恰相反;(4)运动表型与能量代谢之间存在显著相关性,表现在游动悬浮时间与有氧代谢酶(MDH、CS)活性呈显著正相关(P0.001),争斗时间与无氧代谢酶(PK、HK、LDH)及乳酸(LD)含量呈显著正相关(P0.05)。结果表明,社群等级高的雄性个体运动能力强,具有较高的生存适应性。而社群等级高的雌性个体多处于静止状态,以便更好地储存能量用于繁殖。研究结果为金乌贼健康苗种培育以及规模化繁殖技术优化提供了理论依据。

Effects of social hierarchy on the behavioral phenotype and energy metabolism of Sepia esculenta in the reproductive period

An experimental ecological method was used to examine the formation of social hierarchy and its effect on the behavior and energy metabolism of Sepia esculenta during the breeding process. We determined the activities of hexokinase (HK), pyruvate kinase (PK), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), citrate synthase (CS), as well as the concentration of lactic acid (LD) in the gonads and wrist muscle of both sexes. The results showed that there were significant differences in the behavioral phenotypes between male and female with the same social hierarchy level. The time spent on swimming and fighting was significantly higher in the dominant males than that in the submissive males. For the females, the time spent on resting was significantly elevated in the dominant animals than that in the submissive individuals. Contrarily, the significantly lower time spent on swimming was observed in the dominant females compared with that in the submissive females. For the dominant males, anaerobic metabolism process produced energy for fighting and aerobic metabolism process produced energy for swimming. The activities of key enzymes in anaerobic metabolism (PK, HK, LDH) in the muscles of dominant males were significantly higher than those of submissive individuals (P < 0.05). Similar results were true for the activities of key enzymes in aerobic metabolism (MDH, CS). However, these enzyme activities did not differ significantly among dominant females and submissive females (P > 0.05). During the breeding period, the females allowed energy to be used more efficiently for the spawning and reproduction due to the reduction of time spent on exercise, which evidenced by the increased activities of MDH and CS in gonads and the decreased activities of those enzymes in muscles. There was a significant correlation between behavioral phenotype and energy metabolism, since the time spent on swimming was positively correlated with the activities of MDH and CS (P < 0.001) and the time spent on fighting was positively correlated with the PK, HK and LDH activities, and LD concentration (P < 0.05). These findings suggest that the energy is preferentially used for exercise in males compared with females in the higher social hierarchy. Females in the higher social hierarchy are more likely to remain dormant to allow energy to be used more efficiently for reproduction. Our findings provide a theoretical basis for the large-scale breeding of healthy S. esculenta and reproduction technology in the spawning period.