Male-limited secondary sexual trait interacts with environment in determining female fitness

Selection for secondary sexual traits (SSTs) elaboration may increase intralocus sexual conflict over the optimal values of traits expressed from shared genomes. This conflict can reduce female fitness, and the resulting gender load can be exacerbated by environmental stress, with consequences for a population’s ability to adapt to novel environments. However, how the evolution of SSTs interacts with environment in determining female fitness is not well understood. Here, we investigated this question using replicate lines of bulb mites selected for increased or decreased prevalence of a male SST—thickened legs used as weapons. The fitness of females from these lines was measured at a temperature to which the mites were adapted (24°C), as well as at two novel temperatures: 18°C and 28°C. We found the prevalence of the SST interacted with temperature in determining female fecundity. At 28°C, females from populations with high SST prevalence were less fecund than females from populations i...

针对第二性征（secondary sexual traits, SSTs）强化的定向选择，可能会加剧由共享基因组表达的性状最优值差异引发的位点内性冲突。这类冲突会降低雌性适合度，而由此产生的性别负荷还会因环境胁迫进一步加重，进而对种群适应新环境的能力造成负面影响。然而，目前学界对第二性征演化与环境如何共同调控雌性适合度的机制仍缺乏充分认知。本研究以球根螨（bulb mites）为实验对象，通过定向选择构建了雄性第二性征——即用作武器的加粗步足——出现频率分别升高和降低的重复品系，以此探究上述科学问题。我们分别在螨类适应的温度（24℃）以及两个非适配的新温度（18℃与28℃）下，测定了这些品系雌性个体的适合度。研究发现，第二性征的出现频率与温度在调控雌性繁殖力的过程中存在交互作用。在28℃条件下，第二性征高出现频率种群的雌性个体，其繁殖力低于种群i...