Data from: Field heritability of a plant adaptation to fire in heterogeneous landscapes

The strong association observed between fire regimes and variation in plant adaptations to fire suggests a rapid response to fire as an agent of selection. It also suggests that fire-related traits are heritable, a precondition for evolutionary change. One example is serotiny, the accumulation of seeds in unopened fruits or cones until the next fire, an important strategy for plant population persistence in fire-prone ecosystems. Here, we evaluate the potential of this trait to respond to natural selection in its natural setting. For this, we use a SNP marker approach to estimate genetic variance and heritability of serotiny directly in the field for two Mediterranean pine species. Study populations were large and heterogeneous in climatic conditions and fire regime. We first estimated the realized relatedness among trees from genotypes, and then partitioned the phenotypic variance in serotiny using Bayesian animal models that incorporated environmental predictors. As expected, field heritability was smaller (around 0.10 for both species) than previous estimates under common garden conditions (0.20). An estimate on a subset of stands with more homogeneous environmental conditions was not different from that in the complete set of stands, suggesting that our models correctly captured the environmental variation at the spatial scale of the study. Our results highlight the importance of measuring quantitative genetic parameters in natural populations, where environmental heterogeneity is a critical aspect. The heritability of serotiny, although not high, combined with high phenotypic variance within populations, confirms the potential of this fire-related trait for evolutionary change in the wild.

火制度（fire regime）与植物火适应性状的变异之间存在显著关联，这提示植物可对作为选择因子的火产生快速响应。同时，这也表明与火相关的性状具有可遗传性，而可遗传性是演化改变的前提条件。其中一个典型例证是闭萌性（serotiny）：即种子留存于未开裂的果实或球果中，直至下一次火灾发生，这是火频发生态系统中植物种群得以存续的关键策略。本研究旨在评估该性状在自然生境中对自然选择做出响应的潜力。为此，我们采用单核苷酸多态性（SNP）标记技术，在野外直接估算了两种地中海松的闭萌性遗传方差与可遗传性。本研究的种群规模较大，且其所处的气候条件与火制度均存在较高异质性。我们首先基于基因型估算了个体间的实际亲缘关系，随后采用纳入环境预测因子的贝叶斯动物模型，对闭萌性的表型方差进行分解。正如预期，野外测得的可遗传性（两个物种均约为0.10）低于此前在同质园实验条件下得到的估算值（0.20）。对环境条件更为均一的部分样地子集进行的估算结果，与全部样地的估算结果并无显著差异，这表明我们的模型能够准确捕捉本研究空间尺度下的环境变异。本研究结果凸显了在自然种群中测定数量遗传参数的重要性——而环境异质性正是自然种群研究中的关键考量因素。尽管闭萌性的可遗传性并不高，但结合种群内较高的表型方差，这一结果证实了该火相关性状在野生环境中发生演化改变的潜力。