The chief enemy of an ant is another ant. This is the measure of the ants’ success. It is true of only one other living creature – man. Derek W. Morley 1953 In the end, I suspect it will all come down to a decision of ethics – how we value the natural worlds in which we evolved and now, increasingly, how we regard our status as individuals. Edward O. Wilson 1988 Ants and flowering plants are dominant in most terrestrial ecosystems, and their evolutionary histories have been crossing paths for at least 100 million years (Wilson & Hölldobler 2005). The study of ant-plant interactions has increased markedly over the past century with the monographs by Bequart (1922) and Wheeler (1942), but most especially in the past 50 years since Daniel Janzen's pioneering experimental work on the Central American ant-inhabited acacias (Janzen 1966). During this time, different aspects of the natural history and evolutionary ecology of ant-plant systems have been highlighted in a number of books (Buckley 1982; Beattie 1985; Huxley & Cutler 1991; Gorb & Gorb 2003; Rico-Gray & Oliveira 2007; Hölldobler & Wilson 2010). Research on ant-plant interactions comprises a wide range of topics, including plant defense, pollination, seed dispersal, damage by leaf-cutting ants, seed predation, ant-fed plants, the association of ants with trophobionts (exudate-producing insect herbivores), applied ant ecology (as related to agriculture and restoration), and all forms of combinations among these subjects. Ant-plant interactions are geographically widespread and have already been studied in many types of terrestrial communities. Indeed, they offer an excellent opportunity to investigate the effects of both historical and ecological factors (including global change) on the evolution of mutualistic as well as antagonistic ant-plant systems (Heil & McKey 2003). Most interspecific interactions, however, are highly facultative, and the diversity of species involved in ant-plant associations can vary considerably even over short geographic ranges, suggesting that a landscape approach should be employed when investigating such interaction systems (Bronstein 2015). Our understanding of the ecology and evolution of ant-plant interactions and their effects on community organization requires an assessment of how the diversity of ants and their use of plants varies across regions, landscapes, habitat gradients, and, most importantly, under the effect of different patterns of global change (Kiers et al. 2010).
