Tropical Tritrophic Interactions: Nasty Hosts and Ubiquitous Cascades

In the tropics, the high diversity of species at all trophic levels combined with increased chemical defense and predation intensity create ideal opportunities for interesting research in community ecology. Two particularly useful themes in the realm of tropical tritrophic interactions are trophic cascades and coevolution, and prominent hypotheses generated by these ideas should continue to provide guidance to empirical studies in tropical communities. Trophic cascades and coevolutionary interactions are expected to be different in tropical communities simply because of the increased diversity for most taxa at all trophic levels. However, many of the assumptions about how tropical communities are different from their temperate counterparts are not well tested and could be incorrect. Thus, a major goal of understanding tropical tritrophic interactions is to thoroughly document latitudinal patterns in community attributes such as consumer specialization, plant chemical defense, and intensity of predation. There are no adequate syntheses of trophic cascades and coevolutionary hypotheses for the tropics due to a lack of focused research programs. To explicitly test these hypotheses, tropical ecologists should focus on model systems and must utilize phylogenetic data combined with creative experimental, correlational, observational, and modeling approaches. Myrmecophytes are good candidates as model systems for such a synthetic approach, given the diversity and importance of ant plants in most tropical communities. Tritrophic interactions in tropical communities are usually part of a more complex web with highly variable interaction strengths, yet with the right approaches and study systems, we can determine which interactions are the strongest for particular taxa and ecosystems.