Plasticity of physiology in Lobelia:: Testing for adaptation and constraint
Plasticity of physiology in Lobelia:: Testing for adaptation and constraint
复制标题
DOI：
10.1554/06-050.1
复制
发表时间：
2006-05-01
期刊：
影响因子：
3.3
通讯作者：
Sherrard, Mark
中科院分区：
文献类型：
--
作者：
Caruso, Christina M.;Maherali, Hafiz;Sherrard, Mark
表型可塑性被认为是一个主要的机制，使固着生物，如植物，以适应环境的异质性。然而，许多常见的塑性反应的适应价值尚未通过将这些反应与健身联系起来进行测试。即使可塑性是适应性的，可塑性的成本，如维持可塑性反应的调节途径所需的能量，可能会限制其进化。我们使用了温室实验，以测试是否塑料的生理反应，土壤水分供应（湿与干条件）是适应性和/或昂贵的同类野花半边莲cardinalis和L。梅毒。测定了与碳、水吸收相关的8个生理指标。比叶面积（SLA）、光合速率（A）、气孔导度（g（s））和光合能力（A（max））对土壤水分有效性有可塑性响应。红雀。A（max）的可塑性是适应不良的，A和g（s）的可塑性是适应性的，而SLA的可塑性是适应性中性的。适应性可塑性的本质在L。然而，红雀与以前的研究不同。水分利用较为保守的半边莲，其特征是较低的g（s），在干旱条件下没有较高的适合度。相反，水分充足的L.具有较高g（s）的红雀具有较高的适应性。只有A（max）对干旱有可塑性反应。siphilitica，这种反应是适应性中性。我们没有发现任何生理性状的可塑性成本，无论是L。cardinalis或L. siphilitica，这表明这些性状的可塑性进化不会受到成本的限制。植物对干旱的生理反应被认为是适应性的，但我们的数据表明，这种可塑性可以是适应性中性或适应不良的。
Phenotypic plasticity is thought to be a major mechanism allowing sessile organisms such as plants to adapt to environmental heterogeneity. However, the adaptive value of many common plastic responses has not been tested by linking these responses to fitness. Even when plasticity is adaptive, costs of plasticity, such as the energy necessary to maintain regulatory pathways for plastic responses, may constrain its evolution. We used a greenhouse experiment to test whether plastic physiological responses to soil water availability (wet vs. dry conditions) were adaptive and/or costly in the congeneric wildflowers Lobelia cardinalis and L. siphilitica. Eight physiological traits related to carbon and water uptake were measured. Specific leaf area (SLA), photosynthetic rate (A), stomatal conductance (g(s)), and photosynthetic capacity (A(max)) responded plastically to soil water availability in L. cardinalis. Plasticity in A(max) was maladaptive, plasticity in A and g(s) was adaptive, and plasticity in SLA was adaptively neutral. The nature of adaptive plasticity in L. cardinalis, however, differed from previous studies. Lobelia cardinalis plants with more conservative water use, characterized by lower g(s), did not have higher fitness under drought conditions. Instead, well-watered L. cardinalis that had higher g(s) had higher fitness. Only A(max) responded plastically to drought in L. siphilitica, and this response was adaptively neutral. We detected no costs of plasticity for any physiological trait in either L. cardinalis or L. siphilitica, suggesting that the evolution of plasticity in these traits would not be constrained by costs. Physiological responses to drought in plants are presumed to be adaptive, but our data suggest that much of this plasticity can be adaptively neutral or maladaptive.