Pålsson Aksel, Walther Ursina, Fior Simone, Widmer Alex
Institute of Integrative Biology ETH Zurich Zurich Switzerland.
Ecol Evol. 2024 Oct 21;14(10):e70454. doi: 10.1002/ece3.70454. eCollection 2024 Oct.
Spatially divergent natural selection can drive adaptation to contrasting environments and thus the evolution of ecotypes. In perennial plants, selection shapes life history traits by acting on subsequent life stages, each contributing to fitness. While evidence of adaptation in perennial plants is common, the expression of life history traits is rarely characterized, limiting our understanding of their role in adaptive evolution. We conducted a multi-year reciprocal transplant experiment with seedlings from low and high elevation populations of the alpine carnation to test for adaptation linked to contrasting climates and inferred specific contributions of early life stages to fitness. We assessed genotype by environment interactions in single fitness components, applied matrix population models to achieve an integrated estimate of fitness through population growth rates, and performed trade-off analyses to investigate the advantage of alternate life history traits across environments. We found evidence of genotype by environment interactions consistent with elevational adaptation at multiple stages of the early life cycle. Estimates of population growth rates corroborated a strong advantage of the local genotype. Early reproduction and survival are alternate major contributors to adaptation at low and high elevation, respectively, and are linked by trade-offs that underlie the evolution of divergent life history traits across environments. While these traits have a strong genetic basis, foreign populations express co-gradient plasticity, reflecting the adaptive strategy of the local populations. Our study reveals that selection associated to climate has driven the evolution of divergent life histories and the formation of elevational ecotypes. While the high energy environment and strong competition favor investment in early reproduction at low elevation, limiting resources favor a more conservative strategy relying on self-maintenance at high elevation. The co-gradient plasticity expressed by high-elevation populations may facilitate their persistence under warming climatic conditions.
空间上不同的自然选择可以推动对不同环境的适应，从而促进生态型的进化。在多年生植物中，选择通过作用于后续的生命阶段来塑造生活史特征，每个阶段都对适合度有贡献。虽然多年生植物适应的证据很常见，但生活史特征的表达很少被描述，这限制了我们对它们在适应性进化中作用的理解。我们对高山康乃馨低海拔和高海拔种群的幼苗进行了多年的 reciprocal 移植实验，以测试与不同气候相关的适应性，并推断生命早期阶段对适合度的具体贡献。我们评估了单一适合度成分中的基因型与环境相互作用，应用矩阵种群模型通过种群增长率实现对适合度的综合估计，并进行权衡分析以研究不同环境中交替生活史特征的优势。我们发现了与生命周期早期多个阶段的海拔适应性一致的基因型与环境相互作用的证据。种群增长率的估计证实了本地基因型的强大优势。早期繁殖和存活分别是低海拔和高海拔适应的主要交替贡献因素，并且通过权衡联系在一起，这些权衡是不同环境中不同生活史特征进化的基础。虽然这些特征有很强的遗传基础，但外来种群表现出共梯度可塑性，反映了本地种群的适应性策略。我们的研究表明，与气候相关的选择推动了不同生活史的进化和海拔生态型的形成。虽然高能量环境和激烈竞争有利于低海拔地区对早期繁殖的投入，但有限的资源有利于高海拔地区更依赖自我维持的保守策略。高海拔种群表现出的共梯度可塑性可能有助于它们在气候变暖条件下的持续存在。
