Westergren Marjana, Archambeau Juliette, Bajc Marko, Damjanić Rok, Theraroz Adélaïde, Kraigher Hojka, Oddou-Muratorio Sylvie, González-Martínez Santiago C
Slovenian Forestry Institute, Ljubljana, Slovenia.
INRAE, Univ. Bordeaux, BIOGECO, Cestas, France.
Mol Ecol. 2023 Nov 14. doi: 10.1111/mec.17196.
Local survival of forest tree populations under climate change depends on existing genetic variation and their adaptability to changing environments. Responses to selection were studied in European beech (Fagus sylvatica) under field conditions. A total of 1087 adult trees, seeds, 1-year-old seedlings and established multiyear saplings were genotyped with 16 nuSSRs. Adult trees were assessed for phenotypic traits related to growth, phenology and reproduction. Parentage and paternity analyses were used to estimate effective female and male fecundity as a proxy of fitness and showed that few parents contributed to successful regeneration. Selection gradients were estimated from the relationship between traits and fecundity, while heritability and evolvability were estimated using mixed models and the breeder's equation. Larger trees bearing more fruit and early male flowering had higher total fecundity, while trees with longer growth season had lower total fecundity (directional selection). Stabilizing selection on spring phenology was found for female fecundity, highlighting the role of late frosts as a selection driver. Selection gradients for other traits varied between measurement years and the offspring cohort used to estimate parental fecundity. Compared to other studies in natural populations, we found low to moderate heritability and evolvability for most traits. Response to selection was higher for growth than for budburst, leaf senescence or reproduction traits, reflecting more consistent selection gradients across years and sex functions, and higher phenotypic variability in the population. Our study provides empirical evidence suggesting that populations of long-lived organisms such as forest trees can adapt locally, even at short-time scales.
气候变化下森林树种种群的局域存活取决于现有的遗传变异及其对不断变化环境的适应性。在野外条件下对欧洲山毛榉（Fagus sylvatica）的选择响应进行了研究。使用16个核微卫星标记对总共1087株成年树木、种子、一年生幼苗和已定植多年的幼树进行了基因分型。对成年树木的生长、物候和繁殖相关表型性状进行了评估。利用亲权和父权分析来估计有效雌雄性繁殖力，作为适合度的指标，结果表明很少有亲本对成功更新有贡献。从性状与繁殖力之间的关系估计选择梯度，同时使用混合模型和育种家方程估计遗传力和进化能力。果实较多的大树和雄花早开的树总繁殖力较高，而生长季较长的树总繁殖力较低（定向选择）。发现雌株繁殖力在春季物候上存在稳定选择，突出了晚霜作为选择驱动因素的作用。其他性状的选择梯度在测量年份和用于估计亲本繁殖力的后代群体之间有所不同。与自然种群的其他研究相比，我们发现大多数性状的遗传力和进化能力较低到中等。生长性状对选择的响应高于芽萌发、叶片衰老或繁殖性状，这反映出多年和性别功能间更一致的选择梯度，以及种群中更高的表型变异性。我们的研究提供了经验证据，表明像森林树木这样的长寿生物种群即使在短时间尺度上也能进行局域适应。
