| Seed dispersal is an important stage in the life cycle of plants, which may influence the process of ecology such as seed germination, seedling survival, and growth of plant, then influence the spatial distribution of plant communities. Seed dispersal also affect the gene flow within and between populations by influence the evolution of the adaptability and life history of populations. Many relationships between ant and plant have formed during a long evolution, and one of them is ant disperse seeds. The dispersal of seeds by ants, known as myrmecochory, is facilitated by the presence of a seed appendage called elaiosome, which plays a central role in seed dispersal and is considered to be an adaptation for ant dispersal. Generally, ants remove intact diaspores (seed and elaiosome), bring them back to the nest, eat the nutrient body appendage called elaiosome as food reward and reject intact seeds within or outside the nest. Several hypotheses have related removal of seeds to nutritional needs of ants, while others have argued the importance of possible handles (i.e. structures that ants can grasp to carry) in transporting ants. In the field, ants removed the majority of seeds in the first48h of seed exposure, during which seeds may encounter desiccation or soaking, these may influence the dispersal of seeds. Corydalis giraldii Fedde (Papaveraceae), C. pseudoincisa C. Y. Wu (Papaveraceae), Chelidonium majus L.(Papaveraceae) and Epimedium pubescens Maxim (Berberidaceae) are representative myrmecochorous plants, in this study, the interaction between the plants and ants is investigated preliminarily. The abundance and species of ant, the removal rate and dispersal distance of different myrmecochrous plants removed by different dispersal ants, and the effect of elaiosome presence on seed dispersal were investigated. In order to evaluate the function of elaiosome, we compared the role of the elaiosome as an attractant to its role as an aid for seed manipulation. The effect of abiotic factor desiccation and soaking on seed dispersal were also evaluated. Through these researches, we may provide resources for the study on myrmecochorous plants, also theory evidence for the further study of the ecological significance and the mutualistic relationship. The main findings are as follows:1. Myrmecochory is typically considered a diffuse mutualism, with many species of both plants and ants participating. All2385ants captured from the myrmecochorous plants plots wree grouped into2subfamilies (Formicinae and Myrmicinae),9genera and16species, which include10species of seed-dispersing ants. These seed-dispersing ants belong to Formica Linnaeus, Lasius Fabricius, Pheidole Westwood, Tetramorium Mayr, Aphaenogastter Mayr and Myrmica Latreill. Among them, Lasius alienus (Foerster), Pheidole nietner Emery, Formica fusca Linnaeus and Aphaenogastter sp.1were the best seed dispersers. There are6,4,2, and6species ants remove C. giraldii, C. pseudoincisa, Ch.majus, and E. pubescens seeds, respectively. Four ant-dispersed plants had different seed-dispersing ants, various ant species composition, and the best seed dispersers. On the other hand, the same ant specie had different removal rate and dispersal distance when removed different seeds of myrmecochore. The presence of elaiosomes on seeds is important for seeds dispersal, removal of the elaiosome significantly reduced removal rates by ants, excepting for C. pseudoincisa.2. The results indicated that the presence of elaiosomes on seeds might influence ant behaviour and their seed removal rate, elaiosomes either by serving as an attractant for ants or by both acting as a handle and serving as an attractant for ants. No significant differences were observed in ant ’Antennate’,’Examine’ and ’Pick-up attempt’ behaviours among three types of seeds from each plant species, excepting for L. alienus which ’Pick-up attempt’ of seed (S) was greatly higher than that of both seed (SE) and seed (S+H) in C. giraldii, C. pseudoincisa, and Ch. majus plants. For three types of seeds from each plant species, the removal rate of seed (SE) was significantly higher than that of both seed (S+H) and seed (S) in C. giraldii, C. pseudoincisa, Ch.majus, and Viola grypoceras plants by ant L. alienus and in C. giraldii, C. pseudoincisa and V. grypoceras plants by ant Ph. nietneri. In addition, the removal rate of seed (S+H) was significantly higher than that of seed (S) in C. giraldii by ant L. alienus.3. Desiccation and soaking may influence the seeds dispersal, which is associated with the characteristics of myrmecochorous plant. The elaiosomes did not attract ants from a distance, because no significant difference of each treatment was found in ants first contacted and first removed seeds. However, the removal rates of fresh seeds were significantly higher than different levels of desiccated seeds in E. pubescens by F. fusca, C. pseudoincisa and P. nietner, there were no significant difference of fresh seeds and different levels of desiccated seeds in C. giraldii by F. fusca and Ch. majus by P. nietner. The removal rates of fresh seeds were significantly higher than different levels of soaked seeds, excepting for C. pseudoincisa by P. nietner.The results suggest that myrmecochory is a diffuse mutualism, Different plants have different ant species composition, ant disperser, removal rate and dispersal distance. The presence of elaiosomes on seeds may influence seeds dispersal, and these are depending on plants species and seed-dispersing ants. Elaiosomes functions either by serving as an attractant for ants or by both acting as a handle and serving as an attractant for ants, and the role of elaiosomes strongly varied depending on the species of each partner in ant-mediated seed dispersal process. Ants do not choose seeds from a distance before contacted seeds. Myrmecochorous plants have different response to desiccation and soaking, which may influence seeds dispersal and this effect is depend on the characteristic of ant-dispersed plants. |
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