Parental care mitigates carry-over effects of poor early conditions on offspring growth

Poor developmental conditions can have long-lasting negative effects on offspring phenotypes, but impacts often differ among species. Contrasting responses may reflect disparities in experimental protocols among single-species studies or inherent differences among species in their sensitivity to early conditions and/or ability to mitigate negative impacts. We used a common experimental protocol to assess and compare the role of parental care in mitigating effects of poor early conditions on offspring among 4 sympatric bird species in the wild. We experimentally induced low incubation temperatures and examined effects on embryonic developmental rates, hatching success, nestling growth rates, and parental responses. We examined the generality of these effects across 4 species that differ in their phylogenetic history, breeding ecology, and life histories. We found that cooling led to delayed hatching in all species, but carry-over effects on offspring differed among species. Parents of some but not all species increased their offspring provisioning rates in response to experimental cooling with critical benefits for offspring growth rates. Our study shows for the first time that species exhibit clear differences in the degree to which they are affected by poor early conditions. Observed differences among species demonstrate that parental care is a critical mechanism for mitigating potential negative effects on offspring and suggest that parental responses may be constrained to varying degrees by ecology and life histories.

发育条件不佳会对子代表型产生持久的负面影响，但这种影响往往因物种而异。不同物种对此的响应存在差异，这可能源于单物种研究间实验方案的不同，或是不同物种在对早期发育条件的敏感性和/或缓解负面影响的能力上存在固有差异。本研究采用统一的实验方案，对野外环境下4种同域分布鸟类的亲本抚育在缓解早期发育不良对子代的影响中的作用进行评估与比较。我们通过实验手段降低孵化温度，探究其对胚胎发育速率、孵化成功率、雏鸟生长速率以及亲本行为响应的影响。本研究选取系统发育历史、繁殖生态学特征及生活史策略均存在差异的4个物种，探究这些影响在不同物种间的普适性。研究发现，低温处理会导致所有物种的孵化延迟，但对子代的遗留效应存在物种间差异。部分（而非全部）物种的亲本会在实验性低温处理下提升育雏投喂速率，这对子代的生长速率具有关键益处。本研究首次证实，不同物种受早期发育不良影响的程度存在显著差异。观测到的物种间差异表明，亲本抚育是缓解对子代潜在负面影响的关键机制，同时也提示亲本的响应行为可能受到生态学特征与生活史策略的不同程度约束。