Dixon Andrea L, Busch Jeremiah W
School of Biological Sciences, Washington State University, P.O. Box 644236, Pullman, Washington 99164
School of Biological Sciences, Washington State University, P.O. Box 644236, Pullman, Washington 99164.
Am J Bot. 2017 Jun;104(6):817-827. doi: 10.3732/ajb.1600414.
Direct tests of a species distribution model (SDM) were used to evaluate the hypothesis that the northern and southern edges of 's geographical range are limited by temperature and precipitation.
Climatic suitability was predicted using an SDM informed only by temperature and precipitation variables. These predictions were tested by growing plants in growth chambers with temperature and watering treatments informed by weather stations characteristic of environments at the geographic center, edges, and outside the range. An Aster analysis was used to assess whether treatments significantly affected lifetime flower production and to test for local adaptation. The relationship between climatic suitability and lifetime flower number in the growth chambers was also evaluated.
The temperature and watering treatments significantly affected lifetime flower number, although local adaptation was not detected. Flower production was significantly lower under the two edge treatments compared to the central treatment. While no flowers were produced under the beyond-south treatments, flower production was greatest under the beyond-north treatment. These results suggest a hard abiotic limit at the southern edge, and suitable temperature and precipitation conditions beyond the northern edge. While predicted climatic suitability was significantly lower at the range edges, there was no correlation between the climatic suitability of the weather stations' locations and flower production.
These results suggest that temperature and precipitation play a significant role in defining the distribution of , but also indicate that dispersal limitation or metapopulation dynamics are likely important factors restricting access to habitable sites beyond the northern range limit.
使用物种分布模型（SDM）的直接测试来评估以下假设，即[物种名称]地理分布范围的北部和南部边缘受温度和降水限制。
仅使用温度和降水变量的SDM预测气候适宜性。通过在生长室中种植植物来测试这些预测，生长室的温度和浇水处理参考地理中心、边缘及分布范围外环境特征的气象站数据。使用紫菀分析评估处理是否显著影响一生的花产量，并测试局部适应性。还评估了生长室中气候适宜性与一生花数量之间的关系。
温度和浇水处理显著影响一生的花数量，尽管未检测到局部适应性。与中心处理相比，两种边缘处理下的花产量显著较低。虽然在南部范围外处理下未产生花，但在北部范围外处理下花产量最高。这些结果表明南部边缘存在硬非生物限制，而北部边缘以外有适宜的温度和降水条件。虽然预测的气候适宜性在分布范围边缘显著较低，但气象站位置的气候适宜性与花产量之间没有相关性。
这些结果表明温度和降水在定义[物种名称]的分布中起重要作用，但也表明扩散限制或集合种群动态可能是限制进入北部分布范围以外适宜栖息地的重要因素。
