Abstract:

A mutualism of ants with Codariocalyx motorius has been formed through a long interrelationship and co-evolution.The effectiveness of ants in removing seed of Codariocalyx motorius has been studied together with its effects on seed predation by rodents in Simao and Xishuangbanna of Yunnan Province,China.The results show that dispersing distances of seed removed from their mother plants by ants are not very great,with averages of 0.93～2.53 m,but exceed the shooting distance attained by seeds themselves.Each of ants,which are leading remover of C.motorius seed,has its own peak in the removing distance curve.When ants can not access the seeds,the predating ratios of C.motorius seed by rodents are 28.3% and 16.5% respectively in Jinggu and Menglun,in contrast with the high rates(77%,daily and 35.7%,night)of dispersal by ants when rodents can not predate the seeds.The shooting time of mature seed falls into the ants' periods of activity,and therefore ants can effectively remove the seed before rodents reach it.The experiments show that coexistence of C.motorius with ants is beneficial to protection and dispersal of the seed,as well as reduction of seed loss by rodents,and so promotes the development of the plant population.

Key words: Codariocalyx motorius, ants, mutualism, dispersal of seed, rodents