Comments on “Structuring Herbivore Communities: the Role of Habitat and Diet”

The question Van Wieren and Van Langevelde (Chapter 11) are trying to find an answer to, namely “Why are there so many species?”, and especially “Why are there so many herbivore species at some location?” is an intriguing one, but not a simple one. To solve this question, one must first look into the exact articulation of the question. The word “Why” is particularly knotty. The question could be reformulated as “What causes the existence of so many species?”, but also as “What is the function of so many species?” or even “How did so many species evolve?”. At first sight, Van Wieren and Van Langevelde deal with the first question, about the cause. However, a closer look at the text reveals that they try to find an answer to another question than the one they pose, namely, “What allows so many different species to co-exist?”. This is a pity, because if they had tried to find an answer to the question about causality, then they would have taken, hopefully, an evolutionary and dynamic approach. Now their approach is static, and focuses on the conditionality instead of the causality.