Dogs are derived from wolves. today, dogs are very diverse, varying in size from very small to very large. what led to this variety?

I would say evolution because when the wolf's became domestic they no longer needed to hunt down their pray because the humans would feed them, and eventually they lost some Instinct on hunting. Humans also took them all over the world and they slowly started to adapt to their surroundings, so the smaller dogs could be small because of evolution but it is more likely to be because of cross breeding and the genetics they got from that.

What have scientists learned about plant behavior by studying the dodder plant

The rate that would change would be the  searching efficiency/attack rate. there are only two other rates in this model: the  growth rate of prey, and the  predator or consumer mortality rate.the  searching efficiency/attack rate is what indicates how effectively can a predator capture its prey whether in the searching process or actual capturing/attacking process.