EFFECTS OF PREDATOR-SPECIFIC DEFENSE ON BIODIVERSITY AND COMMUNITY COMPLEXITY IN 2-TROPHIC-LEVEL COMMUNITIES

Antipredator strategies employed by prey may be specific (effective ag ainst only one type of predator) or non-specific (effective against al l predators). To examine the effects of the specificity of antipredato r behaviour on biodiversity and community complexity, we analyse mathe matical models including both evolutionary and population dynamics of a system including multiple prey species and multiple predator species . The models assume that all predator species change in their prey cho ice and all prey species have evolutionary change in their antipredato r effort in evolution. The traits of each species change in an adaptiv e manner, whose rate is proportional to the slope of their fitness fun ction. We calculate community complexity, resource-overlap between pre dators, an index of biodiversity and other properties of the co-evolut ionarily stable community for two cases: (1) all prey species have non -specific antipredator behaviour and (2) all prey species have predato r-specific defence. Predator-specificity in defence increases communit y complexity, resource-overlap between predators, the total abundance of predators and the ratio of predator to prey abundance. Specific def ence also decreases the number of isolated subwebs within the entire f oodweb.