Zoological Institute University of Basel, Vesalgasse 1, Basel, Switzerland
Institute of Plant and Microbial Biology University of Zürich, Zollikerstrasse 107, Zurich, Switzerland.
Mol Biol Evol. 2016 Dec;33(12):3194-3204. doi: 10.1093/molbev/msw200. Epub 2016 Sep 22.
Diapause is an adaptation that allows organisms to survive harsh environmental conditions. In species occurring over broad habitat ranges, both the timing and the intensity of diapause induction can vary across populations, revealing patterns of local adaptation. Understanding the genetic architecture of this fitness-related trait would help clarify how populations adapt to their local environments. In the cyclical parthenogenetic crustacean Daphnia magna, diapause induction is a phenotypic plastic life history trait linked to sexual reproduction, as asexual females have the ability to switch to sexual reproduction and produce resting stages, their sole strategy for surviving habitat deterioration. We have previously shown that the induction of resting stage production correlates with changes in photoperiod that indicate the imminence of habitat deterioration and have identified a Quantitative Trait Locus (QTL) responsible for some of the variation in the induction of resting stages. Here, new data allows us to anchor the QTL to a large scaffold and then, using a combination of a new mapping panel, targeted association mapping and selection analysis in natural populations, to identify candidate genes within the QTL. Our results show that variation in a rhodopsin photoreceptor gene plays a significant role in the variation observed in resting stage induction. This finding provides a mechanistic explanation for the link between diapause and day-length perception that has been suggested in diverse arthropod taxa.
休眠是一种适应机制，使生物能够在恶劣的环境条件下生存。在分布范围广泛的物种中，休眠诱导的时间和强度可以在不同种群中发生变化，从而揭示出局部适应的模式。了解与这种适应性相关的遗传结构将有助于阐明种群如何适应其当地环境。在周期性的完全孤雌生殖甲壳动物大型溞中，休眠诱导是一种与有性生殖相关的表型可塑性生命史特征，因为无性雌性具有转向有性生殖并产生休眠阶段的能力，这是它们在栖息地恶化时生存的唯一策略。我们之前已经表明，休眠阶段产生的诱导与指示栖息地恶化即将到来的光周期变化相关，并确定了一个与休眠阶段诱导的一些变异有关的数量性状基因座 (QTL)。在这里，新的数据使我们能够将 QTL 锚定到一个大的支架上，然后，使用新的图谱面板、靶向关联图谱和自然种群中的选择分析，在 QTL 内识别候选基因。我们的结果表明，视蛋白感光基因的变异在休眠诱导的变异中起着重要作用。这一发现为休眠与日长感知之间的联系提供了一种机制解释，这种联系在不同的节肢动物类群中已经被提出。
