Data from: Evidence for genetic differentiation in timing of maturation among nine-spined stickleback populations

Timing of maturation is an important life-history trait that is likely to be subjected to strong natural selection. Although population differences in timing of maturation have been frequently reported in studies of wild animal populations, little is known about the genetic basis of this differentiation. Here, we investigated population and sex differences in timing of maturation within and between two nine-spined stickleback (Pungitius pungitius) populations in a laboratory breeding experiment. We found that fish from the high-predation marine population matured earlier than fish from the low-predation pond population and males matured earlier than females. Timing of maturation in both reciprocal hybrid crosses between the two populations was similar to that in the marine population, suggesting that early timing of maturation is a dominant trait, whereas delayed timing of maturation in the pond is a recessive trait. Thus, the observed population divergence is suggestive of strong natural selection against early maturation in the piscine-predator-free pond population.

成熟时机是一项重要的生活史特征，很可能受到强烈自然选择的作用。尽管野生动物种群研究中已频繁报道过成熟时机的种群差异，但学界对这类分化的遗传基础仍知之甚少。本研究通过实验室繁殖实验，针对两个九棘刺鱼（nine-spined stickleback, *Pungitius pungitius*）种群内部及种群间的成熟时机的种群差异与性别差异展开了探究。结果显示，来自高捕食压力海洋种群的个体，其成熟时间早于低捕食压力池塘种群的个体；且雄性个体的成熟时间早于雌性个体。两个种群间的正反交后代的成熟时机均与海洋种群相近，这表明较早的成熟时机属于显性性状，而池塘种群中延迟的成熟时机则为隐性性状。综上，本次观测到的种群分化提示，在无鱼类捕食者的池塘种群中，存在针对早熟个体的强烈自然选择压力。