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.

观测到的火灾制度与植物火适应变异间的强关联，表明植物可对作为选择因子的火灾做出快速响应。这同时也暗示，与火相关的性状具有可遗传性，而可遗传性正是演化改变的前提条件。其中一个典型案例便是闭萌性（serotiny）——即种子储存在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维持存续的重要策略。本研究旨在评估该性状在自然环境中响应自然选择的潜力。为此，我们采用单核苷酸多态性（SNP）标记方法，直接在野外环境中估算两种地中海松属物种的闭萌性的遗传方差与可遗传性。本次研究的种群规模较大，且气候条件与火灾制度均存在显著异质性。我们首先基于基因型估算个体间的实际亲缘关系，随后结合环境预测因子，采用贝叶斯动物模型拆分闭萌性的表型方差。正如预期，野外环境下的可遗传性估计值（两个物种均约为0.10）低于此前在同质园条件下得到的估计值（0.20）。对环境条件更为均一的部分林分进行的子样本估计值，与全部林分的估计值并无显著差异，这表明我们的模型已准确捕捉到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——环境异质性在此类场景中是关键考量因素。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，证实了该火相关性状在野生环境中发生演化的潜力。