Evolutionary aspects of ecological generalism with special reference to conservation biological control

2. I consider two alternatives. Under the Type I mechanism, ecological generalism is exclusively a population property. Under the Type II mechanism, generalism can vary among genotypes as well as among populations. 3. The genetics underlying the Type I mechanism is straightforward, whereas Type II genetics is less so. I propose that a broad adaptive range of generalist genotypes can be a result of a pleiotropic modifier that, when expressed, renders fitness of the carrier relatively insensitive to environmental variance. 4. A review of the theory and the data indicates that stable ecological generalism is more likely to occur under the Type II compared to the Type I mechanism. Type II generalism appears to be relatively more common and more compatible with patterns observed in the wild. 5. Generalism of natural enemies is a key factor influencing the effectiveness of conservation biological control (CBC). I argue that natural enemies with Type II generalism are relatively more suitable for CBC applications, and spell out directions for further research.