Data from: Protein and carbohydrate intake influence sperm number and male fertility in male cockroaches but not sperm viability

It is commonly assumed that because males produce many, tiny sperm, they are cheap to produce. Recent work, however, suggests that sperm production is not cost free. If sperm are costly to produce, sperm number and/or viability should be influenced by diet and this has been documented in numerous species. Yet few studies have examined the exact nutrients responsible for mediating these effects. Here we quantify the effects of protein (P) and carbohydrate (C) intake on sperm number and viability in the cockroach Nauphoeta cinerea, as well as the consequences for male fertility. We found the intake of P and C influenced sperm number, being maximised at a high intake of diets with a P:C ratio of 1:2, but not sperm viability. The nutritional landscapes for male fertility and sperm number were closely aligned suggesting that sperm number is the major determinant of male fertility in N. cinerea. Under dietary choice, males regulate nutrient intake at a P:C ratio of 1:4.95, which is midway between the ratio needed to maximise sperm production and pre-copulatory attractiveness in this species. This raises the possibility that males regulate nutrient intake to balance the trade-off between pre- and post-copulatory traits in this species.

学界普遍认为，由于雄性产生大量微小精子，其生成成本低廉。但近期研究表明，精子生成并非无成本消耗。若精子生成存在成本，则精子数量与/或活力必然会受到饮食的调控，这一结论已在众多物种中得到验证。然而，鲜有研究明确介导此类效应的具体营养组分。本研究以灰林蠊（Nauphoeta cinerea）为对象，量化了蛋白质（Protein, P）与碳水化合物（Carbohydrate, C）的摄入对其精子数量与活力的影响，以及该影响对雄性生育力的后续效应。研究结果显示，蛋白质与碳水化合物的摄入会显著影响精子数量：当摄入P:C比例为1:2的高营养日粮时，精子数量达到峰值，但精子活力未受该营养比例的显著影响。雄性生育力与精子数量对应的营养景观高度吻合，这表明在灰林蠊中，精子数量是雄性生育力的核心决定因素。在可自由选择日粮的条件下，雄性会将营养摄入的P:C比例调控为1:4.95，该比例恰好介于本物种中最大化精子生成所需的比例与最大化交配前吸引力所需的比例之间。这一发现提示，该物种的雄性可能通过调控营养摄入，来平衡交配前与交配后繁殖性状之间的生活史权衡。