Knight Charles A, Ackerly David D
Department of Biological Sciences, Stanford University, Stanford, CA, 94305-5020, USA.
Oecologia. 2002 Feb;130(4):505-514. doi: 10.1007/s00442-001-0841-0. Epub 2002 Feb 1.
The hypothesis that species inhabiting warmer regions have greater photosynthetic tolerance of high temperatures was tested using the temperature-dependent increase in fluorescence (T-F ). Congeneric species pairs of Atriplex, Salvia, Encelia, and Eriogonum with desert versus coastal distributions were studied in a common environment and in the field. In addition, 21 species with contrasting microclimate distributions were studied at a field site in a northern California chaparral community. The average July maximum temperature within the current distributions of species was quantified using a geographic information system. Four parameters (T , T , T , and T ) of the T-F response were used to quantify photosynthetic thermotolerance. In the common environment, only the desert Atriplex species was significantly greater for all T-F parameters when compared to its coastal congener. In the field, desert species had significantly greater T , T , T , and T when compared to coastal species. The magnitude of variation between species and between genera was similar in the common environment and the field. However, T , T , T and T were all significantly greater when measured in the field. There was no relationship between T-F parameters and the microclimate distribution of the 21 species at the chaparral field site. In addition, T-F parameters for all 35 species were not correlated with the average July maximum temperature within the species ranges. However, there was a significant negative correlation between the average annual amount of precipitation inside species' ranges and T . Our results show that photosynthetic thermotolerance is (1) significantly different between genera and species, (2) highly plastic, (3) not necessarily greater for species with warm climate distributions when measured in a common environment, but (4) significantly greater overall for desert species compared to coastal species when measured in the field.
利用荧光随温度升高的变化（T-F）对“栖息于温暖地区的物种具有更高的高温光合耐受性”这一假设进行了验证。对滨藜属、鼠尾草属、绢蒿属和荞麦属中具有沙漠与沿海分布的同属物种对，在共同环境和野外进行了研究。此外，在加利福尼亚北部灌丛群落的一个野外地点，对21种具有不同小气候分布的物种进行了研究。利用地理信息系统对物种当前分布范围内7月的平均最高温度进行了量化。采用T-F响应的四个参数（T₁、T₂、T₃和T₄）来量化光合耐热性。在共同环境中，与沿海同属物种相比，只有沙漠滨藜属物种的所有T-F参数都显著更高。在野外，与沿海物种相比，沙漠物种的T₁、T₂、T₃和T₄显著更高。在共同环境和野外，物种间和属间的变异幅度相似。然而，在野外测量时，T₁、T₂、T₃和T₄都显著更高。在灌丛林地野外地点，T-F参数与21种物种的小气候分布之间没有关系。此外，所有35种物种的T-F参数与物种范围内7月的平均最高温度均无相关性。然而，物种分布范围内的年平均降水量与T₁之间存在显著的负相关。我们的结果表明，光合耐热性（1）在属和种之间存在显著差异，（2）具有高度可塑性，（3）在共同环境中测量时，气候温暖分布的物种不一定更高，但（4）在野外测量时，沙漠物种总体上比沿海物种显著更高。
