|| 要旨トップ | 目次 |||日本生態学会第61回全国大会 (2014年3月、広島) 講演要旨
一般講演（口頭発表） B2-11 (Oral presentation)
Corruption is one of the most serious obstacles for ecosystem management. More than half of the loss of forested area in many tropical countries is due to illegal logging. Here we study an evolutionary game model to analyze the illegal harvesting of trees in forests, coupled with the corruption of rule enforcers. We consider several types of harvesters, who may or may not be committed towards supporting an enforcer service, and who may cooperate (invest to maintain the forest) or defect (clear up the forest illegally). We also consider two types of rule enforcers: honest and corrupt. The system is bistable: There is a line segment of equilibria consisting of defecting harvesters and a low fraction of honest enforcers; and there is also a line segment of equilibria consisting of cooperating harvesters and a high fraction of honest enforcers. Both line segments attract near-by trajectories. Even a small rate of exploration (or ‘mutation’) among strategies can produce a totally different outcome: the system is globally stable. Depending on the relative rates of exploration among enforcers, most harvesters cooperate, or most all defect. This suggests that education of enforcers can be very important. We discuss information on honesty of enforcers is available.