Laboratory of Artificial & Natural Evolution (LANE), Department of Genetics & Evolution, University of Geneva, 1211 Geneva, Switzerland; SIB Swiss Institute of Bioinformatics, 1211 Geneva, Switzerland.
Laboratory of Artificial & Natural Evolution (LANE), Department of Genetics & Evolution, University of Geneva, 1211 Geneva, Switzerland; SIB Swiss Institute of Bioinformatics, 1211 Geneva, Switzerland.
Curr Biol. 2022 Dec 5;32(23):5069-5082.e13. doi: 10.1016/j.cub.2022.10.044. Epub 2022 Nov 14.
Skin color patterning in vertebrates emerges at the macroscale from microscopic cell-cell interactions among chromatophores. Taking advantage of the convergent scale-by-scale skin color patterning dynamics in five divergent species of lizards, we quantify the respective efficiencies of stochastic (Lenz-Ising and cellular automata, sCA) and deterministic reaction-diffusion (RD) models to predict individual patterns and their statistical attributes. First, we show that all models capture the underlying microscopic system well enough to predict, with similar efficiencies, neighborhood statistics of adult patterns. Second, we show that RD robustly generates, in all species, a substantial gain in scale-by-scale predictability of individual adult patterns without the need to parametrize the system down to its many cellular and molecular variables. Third, using 3D numerical simulations and Lyapunov spectrum analyses, we quantitatively demonstrate that, given the non-linearity of the dynamical system, uncertainties in color measurements at the juvenile stage and in skin geometry variation explain most, if not all, of the residual unpredictability of adult individual scale-by-scale patterns. We suggest that the efficiency of RD is due to its intrinsic ability to exploit mesoscopic information such as continuous scale colors and the relations among growth, scales geometries, and the pattern length scale. Our results indicate that convergent evolution of CA patterning dynamics, leading to dissimilar macroscopic patterns in different species, is facilitated by their spontaneous emergence under a large range of RD parameters, as long as a Turing instability occurs in a skin domain with periodic thickness. VIDEO ABSTRACT.
脊椎动物的皮肤颜色图案是由微观的色素细胞之间的相互作用在宏观尺度上显现出来的。利用五种不同蜥蜴物种在尺度上趋同的皮肤颜色图案动力学,我们量化了随机(伦茨-伊辛和细胞自动机,sCA)和确定性反应扩散(RD)模型各自的效率,以预测个体图案及其统计属性。首先,我们表明,所有模型都足以很好地捕捉底层的微观系统,以相似的效率预测成年图案的邻域统计数据。其次,我们表明,RD 在所有物种中都能稳健地产生个体成年图案的尺度间可预测性的实质性提高,而无需将系统参数化到其许多细胞和分子变量。第三,使用 3D 数值模拟和 Lyapunov 谱分析,我们定量地证明了,考虑到动力系统的非线性,在幼年阶段颜色测量和皮肤几何形状变化的不确定性解释了大部分,如果不是全部的话,成年个体尺度间图案可预测性的剩余不确定性。我们认为,RD 的效率是由于其内在能力,能够利用中间尺度信息,如连续的尺度颜色和生长、尺度几何形状以及图案长度尺度之间的关系。我们的结果表明,CA 图案动力学的趋同进化导致了不同物种中不同的宏观图案,这是由于在大范围的 RD 参数下自发出现,只要在具有周期性厚度的皮肤区域中发生图灵不稳定性。视频摘要。