Data from: How maternal investment varies with environmental factors and the age and physiological state of wild tsetse Glossina pallidipes and Glossina morsitans morsitans

Theory suggests females should optimize resource allocation across reproductive bouts to maximize lifetime reproduction, balancing current and future reproductive efforts according to physiological state and projected survival and reproduction. Tests of these ideas focus on long-lived vertebrates: few measure age-related reproductive output in iteroparous invertebrates, or partition reserves between those allocated to offspring versus mothers. We investigated how maternal age, and environmental and physiological factors influence reproductive investment in wild tsetse, Glossina pallidipes Austen and G. morsitans morsitans Westwood. Tsetse provide a tractable system to measure reproductive allocation. Females exhibit high maternal investment, producing single, large offspring that rely exclusively on maternal reserves. We find that mothers in better physiological condition and experiencing cooler temperatures produce larger offspring. Pupal size increases significantly but weakly with age. In both species, females with less fat invest proportionately more in offspring. Post-partum fat decreases in flies with badly frayed wings: poor flight capability may limit their feeding efficiency, or they may sacrifice more reserves as a terminal investment. Our results support evidence that offspring size increases with maternal size, investment depends on the environment, and females with lower chances of future reproduction invest more into current offspring. We discuss the implications of maternal effects for predicting vector population responses to environmental change.

演化理论表明，雌性生物应优化各繁殖周期的资源分配策略，以最大化终身繁殖成功率；它们需依据自身生理状态、预期存活概率与繁殖潜力，权衡当前与未来的繁殖投入。现有相关假说的验证多聚焦于长寿命脊椎动物，针对多次繁殖无脊椎动物的年龄相关繁殖产出、或亲代资源在子代与自身间分配情况的研究仍较为匮乏。本研究以野外种群的舌蝇（Glossina pallidipes Austen 与 G. morsitans morsitans Westwood）为研究体系，探究母代年龄、环境与生理因素如何影响其繁殖投入。舌蝇是研究繁殖资源分配的理想模型系统：雌性舌蝇具有极高的亲代投入，每次仅产下单一头大型子代，且子代的生长完全依赖母代储存的营养储备。研究结果显示，生理状态更佳、所处环境温度更低的雌性个体，其产下的子代体型更大。蛹的体型随母代年龄增长呈现显著但微弱的上升趋势。两个舌蝇物种均表现出：体内脂肪储备更少的雌性，会按比例向子代投入更多资源。翅翼严重磨损的雌性个体在产后体内脂肪含量会出现下降：这可能是由于飞行能力受损限制了其取食效率，或是此类个体将更多储备作为终端投入消耗。本研究结果佐证了以下结论：子代体型随母代体型增大而增加、繁殖投入受环境因素调控，且预期未来繁殖机会更低的雌性会向当前子代投入更多资源。最后，我们讨论了亲代效应在预测媒介昆虫种群对环境变化的响应方面的研究意义。