图6. 扁桃亚属4种野生植物生态位相似性与驱动因子贡献率。A-F, 生态位可视化。绿色表示第一个种的生态位空间, 红色表示第二个种的生态位空间, 蓝色表示重叠空间。D为生态位重叠分数。G, 驱动因子主成分分析。箭头表示相关的方向(同一方向表示高度相关)。Bio1, 年平均气温; Bio4, 温度季节性变化标准差; Bio5, 最暖月最高气温; Bio6, 最冷月最低气温; Bio15, 降水量的季节性变异系数; Bio17, 最干季降水量; Bio18, 最暖季降水量。环境因子后括号里的数字为贡献率排名。

Fig. 6. Ecological niche differentiation and the contribution of driving factors of four subgen. Amygdalus plants. A-F, Visualization of ecological niches. The green colour depicts the niche space of the first species, red of the second species and the overlapping range is shown in blue. D is the ecological niche overlap score. G, Driver factors principal component analysis. The arrow depicts the direction of correlation (same direction indicates a high correlation). Bio1, annual mean temperature; Bio4, temperature seasonality (standard deviation × 100); Bio5, max temperature of warmest month; Bio6, min temperature of coldest month; Bio15, precipitation seasonality (coefficient of variation); Bio17, precipitation of driest quarter; Bio18, precipitation of warmest quarter. The numbers in brackets after the environmental factors are the contribution rankings.