Collaborative Research: Plant Tolerance of Herbivory: A Test for Constraints on Adaptation

9815873 Weis人类长期以来一直关注害虫对植物性能的影响。 到目前为止，生态学家和农学家都把注意力集中在植物对攻击的抵抗力上，即植物阻止潜在敌人的能力。 然而，昆虫的攻击很少是致命的，因此植物有机会以第二种方式应对敌人的攻击，恢复和再生。 在遭受攻击后还能生存和繁荣的能力叫做容忍。 与抗性遗传学和生态学的研究进展相比，对植物恢复的了解很少。 这种知识的空白阻碍了对整个植物防御系统的理解。 不仅要研究容忍本身的成本效益结构，我们还需要了解容忍，以了解抵抗的适应价值。 抵抗和容忍的相互依赖性来自两个方面的考虑。 首先，抗性和耐受性可能是多余的--如果一种植物可以从攻击中完全恢复，那么抵抗攻击也没有什么好处。 第二个考虑来自最佳防御理论。 人们普遍认为，抗性因素是昂贵的，因为用于抗性的资源不能也分配给增长。 许多实验已经验证了这一假设，但结果喜忧参半。 最近的模型表明，抵抗成本很难被发现，因为它们被容忍成本所掩盖。 但是，由于对宽容知之甚少，对宽容的成本也知之甚少。 因此，没有什么基础来评估这些重要的理论预测。 这些实验将使用一种野生芥菜种芸苔（Brassica campestris）来寻找耐受性成本，芸苔是重要的油料种子作物油菜的野生祖先。将执行人工选择以确定遗传权衡是否施加约束B的能力的适应性成本。campestris耐受落叶。 该实验涉及选择每代经历严重损害的植物品系、从未经历损害的品系和经历两者的品系中的性能。 选择将由sib选择。 经过几代选择后，将通过在所有损害环境中生长来测量品系之间的耐受性差异。 这些实验，因此，将测试几个主要的假设遗传限制的耐受性，并将启动一个长期的努力，以确定生理特性，和潜在的遗传位点，有助于植物恢复。 此外，通过检查两种环境下的选择反应，这些实验将提供对表型可塑性选择约束的更普遍问题的见解。

9815873WeisHumans have long been concerned about the impact of insect pests on plant performance. To date ecologists and agronomists have concentrated on plant resistance to attack, that is, the plant's ability to deter potential enemies. However, insect attack is rarely fatal and so plants have the opportunity for a second way to deal with enemy attack, to recover and regrow. The ability to survive and prosper after attack is called tolerance. Compared to the research progress in understanding the genetics and ecology of resistance, very little is known about plant recovery. This knowledge void hampers understanding of the total plant defense system. Not only is it important to study the cost-benefit structure of tolerance in it own right, we also need to understand tolerance to understand the adaptive value of resistance. The interdependence of resistance and tolerance emerges from two considerations. First, resistance and tolerance can be redundant-if a plant can completely recover from attack, there is little profit in also resisting attack. The second consideration arises from optimal defense theory. It is widely hypothesized that resistance factors are costly since resources devoted to resistance cannot also be allocated to growth. Numerous experiments have tested this hypothesis, but with mixed results. Recent models suggest that resistance costs are hard to detect because they are obscured by tolerance costs. But because little is known about tolerance, little is known about tolerance costs. Thus, there is little basis for evaluating these important theoretical predictions. These experiments will look for tolerance costs using a wild mustard species, Brassica campestris, which is the wild progenitor of canola, the important oil seed crop. Artificial selection will be perform to determine if genetic trade-offs impose a fitness cost that constrains the ability of B. campestris to tolerate defoliation. This experiment involves selecting for performance in plant lines that experience sever damage every generation, lines that never experience damage, and lines that experience both. Selection will be by sib-selection. Following several generations of selection, tolerance differences among the lines will be measured by growing them across all damage environments. These experiments, thus, will test several major hypotheses about genetic constraints on tolerance, and will initiate a long-term effort to identify the physiological traits, and the underlying genetic loci, that contribute to plant recovery. In addition, by examining selection response across two environments, these experiments will offer insights on the more general problem of constraints on selection for phenotypic plasticity.H:\popbio\abstracts\fy1999\9815873 (Weis abstract)