Data from: Intraspecific niche models for ponderosa pine (Pinus ponderosa) suggest potential variability in population-level response to climate change.

Unique responses to climate change can occur across intraspecific levels, resulting in individualistic adaptation or movement patterns among populations within a given species. Thus, the need to model potential responses among genetically distinct populations within a species is increasingly recognized. However, predictive models of future distributions are regularly fit at the species level, often because intraspecific variation is unknown or is identified only within limited sample locations. In this study, we considered the role of intraspecific variation to shape the geographic distribution of ponderosa pine (Pinus ponderosa), an ecologically and economically important tree species in North America. Morphological and genetic variation across the distribution of ponderosa pine suggest the need to model intraspecific populations: the two varieties (var. ponderosa and var. scopulorum) and several haplotype groups within each variety have been shown to occupy unique climatic niches, suggesting populations have distinct evolutionary lineages adapted to different environmental conditions. We utilized a recently-available, geographically-widespread dataset of intraspecific variation (haplotypes) for ponderosa pine and a recently-devised lineage distance modeling approach to derive additional, likely intraspecific occurrence locations. We confirmed the relative uniqueness of each haplotype-climate relationship using a niche-overlap analysis, and developed ecological niche models (ENMs) to project the distribution for two varieties and eight haplotypes under future climate forecasts. Future projections of haplotype niche distributions generally revealed greater potential range loss than predicted for the varieties. This difference may reflect intraspecific responses of distinct evolutionary lineages. However, directional trends are generally consistent across intraspecific levels, and include a loss of distributional area and an upward shift in elevation. Our results demonstrate the utility in modeling intraspecific response to changing climate and they inform management and conservation strategies, by identifying haplotypes and geographic areas that may be most at risk, or most secure, under projected climate change.

种内水平上可出现对气候变化的独特响应，进而导致同一物种种群间出现个体化的适应或迁移模式。因此，学界日益认识到，有必要对物种种内遗传分化种群的潜在响应开展建模。然而，未来分布的预测模型通常以物种水平进行拟合，这往往是因为种内变异（intraspecific variation）数据未知，或仅在有限的采样点位中得以识别。本研究聚焦种内变异对北美地区兼具生态与经济价值的重要树种——黄松（Pinus ponderosa）地理分布的塑造作用。黄松分布范围内的形态与遗传变异表明，有必要对其种内种群开展建模：已有研究显示，该物种的两个变种（北美黄松原变种var. ponderosa与落基山黄松变种var. scopulorum）以及每个变种内的若干单倍型（haplotype）类群均占据独特的气候生态位，暗示其种群拥有适应不同环境条件的独特进化谱系。我们利用新近发布、覆盖广泛地理区域的黄松种内变异数据集，以及新近开发的谱系距离建模方法，推导得到更多潜在的种内分布点位。我们通过生态位重叠分析验证了各单倍型-气候关联的相对独特性，并构建了生态位模型（ecological niche models, ENMs），以在未来气候情景下预测两个变种与八个单倍型的分布范围。单倍型生态位分布的未来预测结果普遍显示，其潜在分布区萎缩幅度较变种水平的预测结果更大。这一差异或反映了不同进化谱系的种内响应特征。不过，种内不同层级的响应趋势整体保持一致，均表现为分布面积缩减与海拔向上迁移。本研究结果证实了针对种内气候变化响应开展建模的实用性，并通过识别气候变化情景下风险最高或最具保护价值的单倍型与地理区域，为管理与保护策略制定提供了科学依据。