Mutualism benefits partner species and theory predicts these partnerships can affect the abundance, diversity, and composition of partner and non-partner species. We used 16 years of monitoring data to determine the ant partner species of tree cholla cacti (Cylindriopuntia imbricata), which reward ants with extrafloral nectar in exchange for anti-herbivore defense. This long-term data revealed one dominant ant partner (Liometopum apiculatum) and two less common partners (Crematogaster opuntiae and Forelius pruinosus. We then used short-term...