Ehrlén Johan
Department of Botany, Stockholm University, S-106 91 Stockholm, Sweden.
Am Nat. 2003 Dec;162(6):796-810. doi: 10.1086/379350. Epub 2003 Dec 19.
I examined the long-term effects of cryptic mollusk herbivory on seven fitness components in the perennial herb Lathyrus vernus and also calculated measures of total fitness effects. Natural correlations and experimental exclusion of mollusks showed that herbivory is associated with an increased probability of dying or staying dormant, poorer growth, and a lower probability of flowering. The average yearly reduction in population growth rate (lambda) caused by mollusks in the experiment was 0.14. The largest contribution to this decrease in total fitness occurred through a decreased survival of established plants. In contrast, seedling emergence and probability of flowering were the fitness components that were most affected in terms of relative change. The more important a life-cycle transition was for population growth rate in terms of its elasticity, the less it was affected by herbivore damage. These results suggest that simple analyses of the magnitudes of effects on individual components of plant performance are poor predictors of the magnitude of total fitness effects and tolerance to herbivory. This is because total fitness is differently sensitive to different phases of the life cycle and because plants strive to maintain the functions most important to fitness.
我研究了隐匿性软体动物取食对多年生草本植物春箭豌豆七个适合度组分的长期影响，并计算了总适合度效应的指标。自然相关性以及对软体动物的实验排除表明，取食与死亡或保持休眠的概率增加、生长较差以及开花概率降低有关。在实验中，软体动物导致的种群增长率（λ）的年平均降低为0.14。总适合度下降的最大贡献来自已定植植物存活率的降低。相比之下，就相对变化而言，幼苗出土和开花概率是受影响最大的适合度组分。就其弹性而言，对于种群增长率越重要的生命周期转变，受食草动物损害的影响就越小。这些结果表明，对植物表现的各个组分影响程度的简单分析，并不能很好地预测总适合度效应的大小以及对食草作用的耐受性。这是因为总适合度对生命周期的不同阶段敏感性不同，并且植物会努力维持对适合度最重要的功能。
