Data from: Genetic constraints on dishonesty and caste dimorphism in an ant

The ultimate causes of honest signaling remain a subject of debate, with questions remaining over the relative importance of costs and constraints. Signal costs may make dishonesty prohibitively expensive, while genetic constraints could make it impossible. We investigated honest signaling using full-sib analysis and parent-offspring regression in the ant Lasius niger, in which queens produce a cuticular hydrocarbon-based pheromone that signals fertility and inhibits worker reproduction and aggression. We found multiple lines of evidence that cuticular hydrocarbon production is genetically correlated with oogenesis and that the queen pheromone 3-methylhentriacontane and other 3-methylalkanes have strong genetic links with fertility relative to other cuticular hydrocarbons. These genetic correlations may maintain honesty in the face of directional selection on signaling and explain the putatively widespread use of cuticular hydrocarbons in fertility signaling across the social insects. We also found evidence for a positive genetic correlation for fertility between the castes; that is, the most fertile queens produced especially fertile workers. These results highlight that intercaste genetic correlations could constrain the evolution of queen-worker dimorphism, such that worker reproduction may sometimes reflect a nonadaptive “caste load” rather than positively selected cheating.诚实信号传递（honest signaling）的终极成因至今仍是学界争论的焦点，关于信号代价与遗传限制的相对重要性仍存在诸多疑问。信号代价可使欺骗行为的成本高到难以承受，而遗传限制则可能让欺骗完全无法实现。我们以黑毛蚁（Lasius niger）为研究对象，通过全同胞分析（full-sib analysis）与亲子回归（parent-offspring regression）方法探究了诚实信号传递机制。该物种的蚁后会产生基于表皮碳氢化合物（cuticular hydrocarbon）的信息素，用以传递生育力信号并抑制工蚁的繁殖行为与攻击行为。我们发现多组证据表明，表皮碳氢化合物的产生与卵子发生（oogenesis）存在遗传相关性；且相较于其他表皮碳氢化合物，蚁后信息素3-甲基三十一烷（3-methylhentriacontane）以及其他3-甲基烷烃与生育力存在较强的遗传关联。这类遗传相关性可在信号传递受到定向选择的情况下维持信号的诚实性，同时也解释了为何社会性昆虫中广泛存在利用表皮碳氢化合物进行生育力信号传递的现象。我们还发现不同品级间的生育力存在正向遗传相关性：即生育能力最强的蚁后，其所产下的工蚁生育能力也相对更强。上述研究结果凸显了跨品级遗传相关性对蚁后-工蚁二态性演化的约束作用，即工蚁的繁殖行为有时可能并非受正向选择的欺骗行为，而是一种非适应性的“品级负荷（caste load）”。