Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA.
Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ, 0 8544, USA.
Nat Commun. 2018 Oct 22;9(1):4391. doi: 10.1038/s41467-018-06793-y.
Sex differences in immunity are found in many species. Known immune mechanisms in birds and mammals suggest that pathogen detection may be amplified in females, whereas in males, pathogen killing is amplified. We show that these immunological profiles emerge as distinct peaks on a fitness landscape defined by sensitivity-specificity and infection-immunopathology immune tradeoffs. What selection pressures might drive males and females towards separate peaks? Surprisingly, modeling immune trade-offs alone results in a pattern of sex differences that is the reverse of what is observed. By integrating these trade-offs into a life-history framework, where the schedule and magnitude of reproductive investment differs between the sexes, we find that increased age-specific infection and mortality risks during parental investment can push females towards the peak that aligns with empirical observations. Overall, our model suggests enhanced pathogen detection (in females) versus enhanced pathogen killing (in males) is best explained if shared immune tradeoffs interact with sex-specific reproductive schedules and risks. We suggest ways to test this framework empirically.
在许多物种中都存在免疫功能的性别差异。鸟类和哺乳动物的已知免疫机制表明，病原体的检测可能在雌性中放大，而在雄性中，病原体的杀伤被放大。我们表明，这些免疫特征出现在由敏感性-特异性和感染-免疫病理免疫权衡定义的适应度景观上的两个明显峰上。哪些选择压力可能促使男性和女性走向不同的高峰？令人惊讶的是，仅通过模拟免疫权衡，就会产生一种与观察到的情况相反的性别差异模式。通过将这些权衡整合到一个生活史框架中，其中性别之间的繁殖投资的时间安排和幅度不同，我们发现，在父母投资期间，年龄特异性感染和死亡率风险的增加会促使女性朝着与经验观察一致的高峰移动。总的来说，如果共享的免疫权衡与性别特异性的繁殖计划和风险相互作用，那么我们的模型表明，增强的病原体检测（在女性中）与增强的病原体杀伤（在男性中）的最佳解释是增强的病原体检测（在女性中）与增强的病原体杀伤（在男性中）。我们提出了一些方法来通过实证检验这个框架。
