Liu Yang, Barot Sébastien, El-Kassaby Yousry A, Loeuille Nicolas
Department of Forest and Conservation Sciences University of British Columbia Vancouver BC Canada.
Sorbonne Universités Institute of Ecology and Environmental Sciences (UMR 7618, UPMC, CNRS, INRA, IRD) Paris France.
Ecol Evol. 2016 Nov 27;7(1):26-37. doi: 10.1002/ece3.2611. eCollection 2017 Jan.
Seed dormancy and size are two important life-history traits that interplay as adaptation to varying environmental settings. As evolution of both traits involves correlated selective pressures, it is of interest to comparatively investigate the evolution of the two traits jointly as well as independently. We explore evolutionary trajectories of seed dormancy and size using adaptive dynamics in scenarios of deterministic or stochastic temperature variations. Ecological dynamics usually result in unbalanced population structures, and temperature shifts or fluctuations of high magnitude give rise to more balanced ecological structures. When only seed dormancy evolves, it is counter-selected and temperature shifts hasten this evolution. Evolution of seed size results in the fixation of a given strategy and evolved seed size decreases when seed dormancy is lowered. When coevolution is allowed, evolutionary variations are reduced while the speed of evolution becomes faster given temperature shifts. Such coevolution scenarios systematically result in reduced seed dormancy and size and similar unbalanced population structures. We discuss how this may be linked to the system stability. Dormancy is counter-selected because population dynamics lead to stable equilibrium, while small seeds are selected as the outcome of size-number trade-offs. Our results suggest that unlike random temperature variation between generations, temperature shifts with high magnitude can considerably alter population structures and accelerate life-history evolution. This study increases our understanding of plant evolution and persistence in the context of climate changes.
种子休眠和大小是两个重要的生活史特征，它们相互作用以适应不同的环境条件。由于这两个特征的进化都涉及相关的选择压力，因此比较研究这两个特征共同以及独立的进化情况很有意义。我们在确定性或随机温度变化的情景下，使用适应性动力学来探索种子休眠和大小的进化轨迹。生态动力学通常会导致种群结构失衡，而高强度的温度变化或波动会产生更平衡的生态结构。当只有种子休眠发生进化时，它会受到反向选择，温度变化会加速这种进化。种子大小的进化会导致特定策略的固定，当种子休眠降低时，进化后的种子大小会减小。当允许共同进化时，进化变异会减少，而在温度变化的情况下进化速度会加快。这种共同进化情景会系统地导致种子休眠和大小降低以及类似的不平衡种群结构。我们讨论了这可能如何与系统稳定性相关联。休眠受到反向选择是因为种群动态导致稳定的平衡，而小种子是大小-数量权衡的结果。我们的结果表明，与代际间的随机温度变化不同，高强度的温度变化会显著改变种群结构并加速生活史进化。这项研究增进了我们在气候变化背景下对植物进化和持久性的理解。
