De Gasperin Ornela, Duarte Ana, English Sinead, Attisano Alfredo, Kilner Rebecca M
Department of Zoology University of Cambridge Cambridge UK.
Department of Ecology and Evolution University of Lausanne Lausanne Switzerland.
Ecol Evol. 2018 Dec 30;9(1):339-351. doi: 10.1002/ece3.4749. eCollection 2019 Jan.
We tested whether the early-life environment can influence the extent of individual plasticity in a life-history trait. We asked: can the early-life environment explain why, in response to the same adult environmental cue, some individuals invest more than others in current reproduction? Moreover, can it additionally explain why investment in current reproduction trades off against survival in some individuals, but is positively correlated with survival in others? We addressed these questions using the burying beetle which breeds on small carcasses and sometimes carries phoretic mites. These mites breed alongside the beetle, on the same resource, and are a key component of the beetle's early-life environment. We exposed female beetles to mites twice during their lives: during their development as larvae and again as adults during their first reproductive event. We measured investment in current reproduction by quantifying average larval mass and recorded the female's life span after breeding to quantify survival. We found no effect of either developing or breeding alongside mites on female reproductive investment, nor on her life span, nor did developing alongside mites influence her size. In post hoc analyses, where we considered the effect of mite number (rather than their mere presence/absence) during the female's adult breeding event, we found that females invested more in current reproduction when exposed to greater mite densities during reproduction, but only if they had been exposed to mites during development as well. Otherwise, they invested less in larvae at greater mite densities. Furthermore, females that had developed with mites exhibited a trade-off between investment in current reproduction and future survival, whereas these traits were positively correlated in females that had developed without mites. The early-life environment thus generates individual variation in life-history plasticity. We discuss whether this is because mites influence the resources available to developing young or serve as important environmental cues.
我们测试了早期生活环境是否会影响生活史特征中个体可塑性的程度。我们提出以下问题：早期生活环境能否解释为什么在面对相同的成年环境线索时，一些个体在当前繁殖中的投入比其他个体更多？此外，它能否进一步解释为什么在一些个体中，当前繁殖的投入与生存相互权衡，而在另一些个体中却与生存呈正相关？我们利用埋葬甲虫来解决这些问题，这种甲虫在小型动物尸体上繁殖，有时还会携带携播螨。这些螨虫与甲虫一同在相同的资源上繁殖，是甲虫早期生活环境的关键组成部分。我们在雌性甲虫的一生中让它们接触两次螨虫：一次是在幼虫发育期间，另一次是在成年后的首次繁殖事件中。我们通过量化平均幼虫质量来衡量当前繁殖的投入，并记录雌性甲虫繁殖后的寿命以量化生存情况。我们发现，无论是在幼虫发育阶段还是在繁殖阶段与螨虫接触，对雌性甲虫的生殖投入、寿命均无影响，而且在幼虫发育阶段与螨虫接触也不会影响其体型。在事后分析中，我们考虑了雌性甲虫成年繁殖期螨虫数量（而非仅仅是其存在与否）的影响，结果发现，在繁殖期间接触到更高螨虫密度的雌性甲虫会在当前繁殖中投入更多，但前提是它们在幼虫发育阶段也接触过螨虫。否则，在螨虫密度更高的情况下，它们对幼虫的投入会减少。此外，在幼虫发育阶段接触过螨虫的雌性甲虫在当前繁殖投入和未来生存之间表现出权衡关系，而在未接触过螨虫的雌性甲虫中，这些特征呈正相关。因此，早期生活环境会导致生活史可塑性的个体差异。我们讨论了这是否是因为螨虫影响了发育中的幼虫可获得的资源，或者是否作为重要的环境线索。
