What are possible examples for diversifying coevolution

I really have a difficulty in understanding the examples in books. They use technical words which I'm not really familiar of. I'm gonna have a report presentation in the class and it would be embarrassing if I, the reporter, can't even understand what I'm trying to report.

The concept of co-evolution is of an 'arms race' between two interacting species: host-parasite, predator-prey or plant-herbivore for instance. Say the herbivore is taking too much of the plant's resources then the plant 'responds' by protecting its resources in some way, then the herbivore itself 'responds' by finding a way to get around the protection.

In reality, the plant is producing lots of different genetic variants and those which have the best protection against herbivores survive until variants in the herbivores which are better able to survive come along.

A classic example is in the relationship between crossbills and pine trees. Crossbills are specialist feeders on pine cone seeds. The pines produce cones with different morphologies, so some crossbills have longer beaks to deal with one type of cone while others have shorter beaks to deal with other types. In time, the crossbills may diverge into different species.

Here are two links to help you


http://www.sciencedaily.com/releases/200…
http://evolution.berkeley.edu/evolibrary…

Are you talking about convergent evolution?