论昆虫与植物的相互作用和进化的关系

The relation of interaction between insects and plants to evolution

昆虫与植物是陆地生物群落中最为重要的组成部分 ,二者间的相互作用是多方面的 ,其中最为重要的是昆虫选择植物作为食物和生长场所、昆虫为植物传授花粉两方面。该文集中讨论这两方面的相互作用有哪些因素与进化有密切的关系。植食性昆虫根据其寄主植物范围 ,通常分为专食性 (寄主范围窄 )和广食性 (寄主范围广 )。从生态关系来看 ,广食性的取食行为比专食性的更为有利 ,但实际情况却与此相反 ,统观植食性昆虫的取食行为 ,有向专食性演化更为普遍的倾向。专食性发展有利于提高昆虫对寄主植物的选择效率 ,还可缓和天敌作用所造成的压力。根据昆虫与植物相互作用的特点 ,目前已提出很多昆虫与植物的进化理论 ,包括成对的协同进化、弥散的协同进化、群落的协同进化以及顺序进化。在昆虫对寄主植物的选择中 ,以植物对昆虫的影响较昆虫对植物的影响更为重要 ,称为顺序进化是适宜的 ;昆虫为被子植物传授花粉造成互惠共生 。

Insects and plants are important components of the terrestrial biocommunities on the globe ; living together they perform diversified interactions including patterns of insectan trophic activity and mode of pollination. In this paper the relationship between these interactions and evolution is discussed. According to the breadth of hostplant range, phytophagous insects are usually classified into specialists (with narrow host range) and generalists (with broad host range). If the seemingly advantage to feed on many different plants by insects is considered, the generalists would be regarded to attain a higher level of evolution. However, a careful examination on the biocommunities in nature usually gives rise to the hard question of why there are so many specialists among insect herbivores. The explanation seems to lie in the higher efficiency of hostplant foraging and the ease of escaping or avoidance from natural enemies in the specialists. Plant adaptation to insect herbivory presumably would cause corresponding reactions in insects,leading to the proposals of coevolution theory. For hostplant selection by insects, several theories are proposed to clarify the present status as paired reciprocal, diffused and community coevolutions. The precedence of diversification of secondary metabolic chemicals in plants and the mutability and adaptation in insect sensory function as well as learning and memory also lead to the proposal of the theory of sequential evolution or colonization. In pollination the mutualistic adaptations between flowers and pollinator insects are manifested in convincing examples including the changing signalling cues from flowers as scents, colors in different plant species, and the blooming schedules, and the behavioral responses and structural modifications of the pollinator insects.