Tradeoffs in the evolution of plant farming by ants

Diverse forms of cultivation have evolved across the tree of life. Efficient farming requires that the farmer deciphers and actively promotes conditions that increase crop yield. For plant cultivation, this can include evaluating tradeoffs among light, nutrients, and protection against herbivores. It is not understood if, or how, nonhuman farmers evaluate local conditions to increase payoffs. Here, we address this question using an obligate farming mutualism between the ant Philidris nagasau and epiphytic plants in the genus Squamellaria that are cultivated for their nesting sites and floral rewards. We focused on the ants' active fertilization of their crops and their protection against he…