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Does ant-plant mutualism have spillover effects on the non-partner ant community?


Donald, Marion; Miller, Tom EX (2023), Does ant-plant mutualism have spillover effects on the non-partner ant community?, Dryad, Dataset,


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 characterization of the terrestrial ant community via pitfall trapping to sample partner and non-partner ant species across ten plots of varying cactus density. We found that the dominant ant partner tended a higher proportion cacti in plots of higher cactus density, and was also found at higher occurrence within the pitfall traps in higher density plots, suggesting strong positive feedbacks that promote ant partner occurrence where plant partners are available. Despite the strong association and increased partner occurrence, ant community-wide effects from this mutualism appear limited. Of the common ant species, the occurrence of a single non-partner ant species was negatively associated with cactus density and with the increased presence of L. apiculatum. Additionally, the composition and diversity of the ant community in our plots were insensitive to cactus density variation, indicating that positive effects of the mutualism on the dominant ant partner did not have cascading impacts on the ant community. This study provides novel evidence that exclusive mutualisms, even those with strong positive feedbacks, may be limited in the scope of their community-level effects.

Usage Notes


Results of ant species counts from pitfall trapping. Data fields are as follows: ID - unique identifier; Plot - the plot (1-10) in which the pitfalls were placed; Station - pitfall ID; StatID - unique plot and station ID; Latitude - latitudinal coordinates; Longitude - Longitudinal coordinates; Misc - non-ant species that were captured in the pitfall trap; Camponotus_sp1:Temnothorax_sp1 - number of ants of each species found in each pitfall trap


Results of ground cover surveys of eight quadrats within each plot. Data fields are as follows: Plot - the plot (1-10); Quadrant - sampling quadrant (1-8); ID - unique identifier of plot and quadrant; Bare Ground: Other - the percentage of total cover for each of the ground cover types; Cactus details - description of whether the cactus is Cholla or prickly pear; Other details - description of what the other category contains


Results of cactus surveys in the additional plots (9 and 10) in 2013. The data fields follow that of Miller 2020 ( These are: Plot - ten 30m x 30m plots (1-10; Tag_ID - Unique identifier for individuals - Tag_ID's are reused between plots, so the unique individual ID is given by the Plot-TagID combination; Year_t - Calendar year at the start of the transition year (late May or early June); Height_t - Height in year t; Width_t - Maximum width in year t; Perp_t - Width perpendicular to the maximum in year t; NS_t -  Number of new vegetative segments initiated in year t; GoodBuds_t - Number of viable (very likely to flower) flowerbuds in year t; ABFlowerbuds_t - Aborted flowerbuds in year t; Antsp_t - If ants are present, this field gives their species identity - There are four common ant species in this system: Crematogaster opuntiae ('crem'), Liometopum apiculatum ('liom'), Forelius pruinosa ('fore'). Occasionally other ant species are observed and these are indicated by 'other'. Vacant plants are denoted 'vacant'.



National Science Foundation, Award: 1440478, 1655499, 1748133, 1543651, 1754468