|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1997 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1996 : ¥1,600,000 (Direct Cost : ¥1,600,000)
Collecting information from references and researchers on social insects, we have grasped actual situation of studies on sociality andmutualism. As far as sociality, the involved factors are (a) distribution of worker and soldier castes among social insects, (b) the number of individuals per colony, (c) the number of reproductives, and (d) methods of colony reproduction. We have found that haplodiploid organisms have mainly workers, and diploid and parthenogenetic organisms have soldiers for (a). We have not find any clear tendency for other categories.
As far as mutualism, the involved factors are (a) size difference in hosts and symbionts, (b) smbiosis within or outside the body, (c) the degree of vertical transmission, and (d) obligate or facultative symbiosis. We have detected the difference in characteristics between organisms with and without vertical transmission. Based on the above data, we have explored mathematical models to clarify the factors that favors for coevolution of sociality and mutualism. The paper is under preparation to be submitted.
We have also explored mathematical models which contribute partial models of the coevolution. As far as sociality, we have completed a model explaining the relationship between the number of reproductives and asymmetry of reproduction (Tsuji and Tsuji, 1996,1997), and a model explaining age polyethism(Wakano et al., 1998).
We have developed a model on conflict resolution to determine social structure (Yamamura and jormalainen, 1996). We have made clear the condition for evolution of mutualism with vertical transmission (Yamamura, 1996) and surveyed what biodiversity the symbiosis produced in evolutionary history (Yamamura, 1997).