Data from: Effects of inbreeding and temperature stress on life history and immune function in a butterfly

Theory predicts that inbreeding depression should be more pronounced under environmental stress due to an increase in the expression of recessive deleterious alleles. If so, inbred populations may be especially vulnerable to environmental change. Against this background we here investigate effects of inbreeding, temperature stress and its interactions with inbreeding in the tropical butterfly Bicyclus anynana. We use a full-factorial design with three levels of inbreeding (F = 0 / 0.25 / 0.38) and three temperature treatments (2 h exposure to 1, 27 or 39°C). Despite using relatively low levels of inbreeding significant inbreeding depression was found in pupal mass, pupal time, thorax mass, abdomen fat content, egg hatching success, and fecundity. However, stress resistance traits (heat tolerance, immune function) were not affected by inbreeding and interactions with temperature treatments were virtually absent. We thus found no support for an increased sensitivity of inbred individuals to environmental stress, and suspect that such patterns are restricted to harsher conditions. Our temperature treatments evidently imposed stress, significantly reducing longevity, fecundity, egg hatching success, and haemocyte numbers, while fat content, protein content, and lysozyme activity remained unaffected. Males and females differed in all traits measured except pupal time and phenoloxidase activity. Correlation analyses revealed, amongst others, a trade-off between phenoloxidase and lysozyme activity, and negative correlations between fat content and several other traits. We stress that more data are needed on the effects of inbreeding, temperature variation, and sexual differences on insect immune function before more general conclusions can be drawn.理论预测，由于隐性有害等位基因的表达水平升高，近交衰退（inbreeding depression）在环境胁迫下会更为显著。若该结论成立，近交种群对环境变化的敏感性可能会尤其高。基于上述背景，本研究以热带蝴蝶Bicyclus anynana为研究对象，探究近交、温度胁迫及其与近交的交互作用对其产生的影响。本研究采用全因子实验设计，设置3个近交水平（F = 0 / 0.25 / 0.38）与3组温度处理（分别在1℃、27℃或39℃下暴露2小时）。尽管本研究采用的近交水平相对较低，但研究人员在蛹重、蛹期、胸重、腹部脂肪含量、卵孵化率与繁殖力这几项指标中均检测到了显著的近交衰退。然而，抗胁迫性状（耐热性、免疫功能）并未受到近交的影响，且温度处理与近交的交互作用几乎不存在。因此本研究未发现近交个体对环境胁迫的敏感性升高的证据，推测该类模式仅会在更为严苛的胁迫条件下出现。本研究设置的温度处理组显然施加了胁迫效应：其显著降低了受试个体的寿命、繁殖力、卵孵化率与血细胞数量，但未对脂肪含量、蛋白质含量与溶菌酶活性产生影响。除蛹期与酚氧化酶活性外，本研究所测的所有性状均存在显著的性别差异。相关性分析结果显示，除其他关联外，酚氧化酶活性与溶菌酶活性之间存在权衡关系，且脂肪含量与其他多项性状之间呈负相关。研究人员强调，在得出更具普适性的结论前，还需要更多关于近交、温度波动以及性别差异对昆虫免疫功能影响的相关数据。