I am reading an article related to herbivory strategies such as tolerance and defense and their potential linking in trade-offs.

According to Rosenthal and Kotanen (1994), natural selection might simultaneously favor both strategies, even with differences in cost and constraints exist.

But, I do not understand how they involve each other. I personally believe that once a strategy engages in a biology system there is not enough energy for another one. A very simplistic sight, what do you think?

Article Terrestrial plant tolerance to herbivory. Trends Ecol Evol 9:145-148