果实(种子)化学防御与食果实动物的适应对策

Chemical defense of fruits (seeds) and the adaptive strategies of frugivorous animals.

种子植物在果实(种子)成熟后需要防御食果实动物捕食种子,同时要传播种子至适宜萌发的生境。很多植物依赖食果实动物传播种子,称动物传播植物。果实(种子)化学防御是抵御种子捕食者的重要手段。果实(种子)中次生物质包括各种生物碱、生氰糖苷、萜类和酚类等,种类繁多;次生物质的含量随果实成熟过程而变化。次生物质可以抵御动物的捕食,其毒性对种子传播者和种子捕食者没有选择性,即具泛毒性。果肉中的次生物质也可以起到轻泻剂的作用,缩短种子在动物消化道的滞留时间,以影响传播效率。果实(种子)次生物质的产生不受植物环境条件的影响,其产生与果实质量有关。在温带地区,通常SS型果实次生物质含量低,而FL型果实含量高。食果实动物可通过调整捕食行为、摄取环境中特殊物质和获得丰富营养等3个方面适应次生物质。果实(种子)中次生物质的研究对动植物相互作用、协同进化理论具有重要的意义。

Seed plants should protect the fruits and seeds from predating by frugivores when fruits become ripe,and disperse the seeds to the habitat suitable for seed germination.The plants which rely on frugivores to finish seed dispersal are called animal-dispersed plants.Chemical defene of fruits (seeds) is an important way for plants to avoid seed predators.Various secondary substances exist in fruits and seeds including alkaloid,cyanogenic glycoside,terpenoid,and phenolic etc,with the content varied during the growth period of fruits.Secondary substances can defense the frugivores with general toxicity to both seed dispersers and seed predators.The pulp secondary substance can influence the dispersing efficiency by means of changing guts retention time acting as laxatives.The production of secondary substances not only depends on the environment factors of plants,but has some relationship with fruits quality.In temperate zone,content of secondary substances is low in summer small-seeded (SS) fruits,while high in fall low-quality (FL) fruits.Frugivores can adjust their foraging behavior,or get special substance from the environment or enough nutrients to reduce the influence of secondary substances.The research of secondary substances is important for the theory of animal-plant interaction and their coevolution.