蚂蚁入侵适应性进化及其机制

入侵种被传至一个新的区域后,在面对当地某些生态因子的胁迫时如何发生适应性变化,是入侵生物学研究的一个重要课题。这方面信息对评价物种的入侵性、制订防控策略具有重要指导意义。入侵性蚂蚁作为无脊椎陆生动物中入侵最成功、危害最严重的一类,其生物学、生态学已得到大量研究,许多报道表明它们在定殖和扩张过程中会发生适应性变化。基于30多年的文献资料,从蚁群社会结构、超级蚁群形成能力、个体大小、觅食行为、种间竞争、天敌防御、适应低温能力、生态位转变等多个角度进行了全面总结,并针对这些方面适应性变化的机制,从表型可塑性、适应性进化、自身遗传学基础、与共生微生物的互利关系等角度进行了剖析。提出了今后有待重点研究的几个问题。将有助于深化对蚂蚁成功入侵机制的认识,为推进我国红火蚁(Solenopsis invicta Buren)、小火蚁(Wasmannia auropunctata Roger)等入侵性蚂蚁的研究与治理提供参考。

Adaptive changes and underlying mechanisms in ant invasions

During establishment and subsequent range expansion, invasive species experience abiotic or biotic factors that are different from those in their native range. As an adaptive response, some of their behavioral, physiological or morphological traits may change to certain degrees. Identifying such changes and underlying mechanisms is critical to invasibility evaluation and risk assessment, and thus informative for the planning of prevention and monitoring means. Invasive ants are among the most widespread and damaging invaders, and some of them have received much research attention in their biology, documented capable of undergoing adaptive changes in their introduced range. Based on the literature over the past 30 years, we summarized such changes by focusing on social structure of colonies, ability to form supercolonies, body size, foraging behavior, interspecific competition, and defense against enemies. Social structure may vary with environments in the division of labor, social form, and between-castes interactions. The ability of forming supercolonies in some invasive ants tends to be higher in introduced regions than in native range. Body size, a key life-history trait influencing invasive ants'' biology and their ecological success, has been demonstrated extensively for its plasticity in invasive ants, which could benefit performances of workers. Foraging and competing behaviours have attracted much interest because of their significance for success of ants; they may be flexibly adjusted by ants according to situations of colonies, competitors, resources or other environmental factors. For a few invasive ants, release from enemies is regarded as one of the major reasons for their success outside native range, where the energy originally used for defences would be deployed to growth, reproduction or other aspects of life. Increased tolerance to adverse ambient temperatures, and adaptive shifts in ecological niches under pressures of resource limit, competitors, and climatic factors, have also been reported to some extent. After this, we analyzed the underlying mechanisms of these changes, in the contexts of phenotypic plasticity, adaptive evolution, genetic basis, and symbiotic relationships with microorganisms. We suggest some topics to be addressed in future studies, including associations between social structure and ecological adaptation in little-studied ant invaders; phenotypic plasticity in behavioural syndromes; increased competitive ability after enemy release; and genetic basis for adaptative changes. We also stress the importance of applying knowledge generated in this field to practice, and the need to strengthen international collaborations in researches. This review will hopefully deepen our understanding of ants'' invasion mechanisms, and provide clues for the research and management of invasive ants in China, e.g., the red imported fire ant, Solenopsis invicta Buren, and the little fire ant, Wasmannia auropunctata Roger.