O'Reilly-Wapstra Julianne M, McArthur Clare, Potts Bradley M
CRC for Sustainable Production Forestry, School of Zoology, University of Tasmania, GPO Box 252-05, 7001, Hobart, Tasmania, Australia.
CRC for Sustainable Production Forestry, School of Plant Science, University of Tasmania, GPO Box 252-55, Hobart, Tasmania, Australia, 7001.
Oecologia. 2002 Jan;130(2):289-296. doi: 10.1007/s004420100797. Epub 2002 Jan 1.
The evolution of plant defensive traits in response to selection pressures imposed by herbivores is central to co-evolutionary theory. To demonstrate the role of herbivores as selective agents on plant resistance there must be variability in plant resistance to herbivores within a plant population. This variability must be under genetic control, and the variability in plant resistant traits and consequently herbivore damage to plants must reflect variability in plant fitness. We used a common eucalypt species, Eucalyptus globulus, and two major mammalian herbivores, the common brushtail possum (Trichosurus vulpecula) and the red-bellied pademelon (Thylogale billardierii), as a system to investigate intraspecific variation in plant resistance to mammalian herbivores and to investigate if this variation has a genetic basis. We measured mammalian browsing damage on 2,302 individual trees of E. globulus, from 563 families derived from range-wide native stand seed collections of known pedigree and grown in a common environment field trial. Using a selection of trees from the field trial we then conducted a feeding trial with captive herbivores to assess if the genetic variation in plant resistance in the field was reflected in feeding preferences of captive animals, as measured by relative intake. Results from the field trial showed significant genetic variation in plant resistance amongst races, localities and amongst different families. These results were consolidated in the captive trial with similar trends in genetic variation among E. globulus localities. Dry matter intake of foliage by Trichosurus vulpecula was consistently greater than that by Thylogale billardierii; however, the intraspecific preferences of the two herbivores were significantly correlated.
植物防御性状因食草动物施加的选择压力而发生的进化是协同进化理论的核心。为了证明食草动物作为植物抗性选择因子的作用，植物种群内对食草动物的抗性必须存在变异性。这种变异性必须受遗传控制，植物抗性性状的变异性以及因此食草动物对植物的损害必须反映植物适合度的变异性。我们使用一种常见的桉树种——蓝桉（Eucalyptus globulus），以及两种主要的哺乳动物食草动物——普通袋貂（Trichosurus vulpecula）和红腹小袋鼠（Thylogale billardierii），作为一个系统来研究植物对哺乳动物食草动物抗性的种内变异，并研究这种变异是否具有遗传基础。我们测量了来自563个家系的2302株蓝桉个体树的哺乳动物啃食损害，这些家系源自已知谱系的广泛原生林种子收集，并种植在一个共同环境的田间试验中。然后，我们从田间试验中挑选树木，对圈养的食草动物进行饲养试验，以评估田间植物抗性的遗传变异是否反映在圈养动物的取食偏好上，取食偏好通过相对摄入量来衡量。田间试验结果表明，不同种族、地点和不同家系之间的植物抗性存在显著的遗传变异。这些结果在圈养试验中得到巩固，蓝桉不同地点之间的遗传变异趋势相似。普通袋貂对树叶的干物质摄入量一直大于红腹小袋鼠；然而，这两种食草动物的种内偏好显著相关。
