How the timing of development is linked to organismal size is a longstanding question. Although numerous studies have reported a correlation of temporal and spatial traits, the developmental or selective constraints underlying this link remain largely unexplored. We address this question by studying the periodic process of embryonic axis segmentation in-vivo in Oryzias fish. Interspecies comparisons reveal that the timing of segmentation correlates to segment, tissue and organismal size. Segment size in turn scales according to tissue and organism size. To probe for underlying causes, we genetically hybridised two closely related species. Quantitative analysis in ~600 phenotypically diverse F2 embryos reveals a decoupling of timing from size control, while spatial scaling is preserved. Using developmental quantitative trait loci (devQTL) mapping we identify distinct genetic loci linked to either the control of segmentation timing or tissue size. This study demonstrates that a developmental constraint mechanism underlies spatial scaling of axis segmentation, while its spatial and temporal control are dissociable modules.

中文翻译：

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脊椎动物轴在时间和空间上分割的模块化控制。


发育时间与生物体大小之间的关系是一个长期存在的问题。尽管许多研究报告了时间和空间特征的相关性，但这种联系背后的发育或选择性限制在很大程度上仍未被探索。我们通过研究 Oryzias 鱼体内胚胎轴分割的周期性过程来解决这个问题。种间比较表明，分段的时间与分段、组织和生物体大小相关。片段大小又根据组织和生物体大小进行缩放。为了探究根本原因，我们对两个密切相关的物种进行了基因杂交。对约 600 个表型多样化的 F2 胚胎的定量分析揭示了时间与大小控制的脱钩，同时保留了空间尺度。使用发育数量性状位点（devQTL）作图，我们识别出与分割时间或组织大小的控制相关的不同遗传位点。本研究表明，轴分割的空间尺度是发育约束机制的基础，而其空间和时间控制是可分离的模块。