Data from: Which traits optimize plant benefits? Meta-analysis on the effect of partner traits on the outcome of an ant-plant protective mutualism

We compilled information from studies providing empirical data about the ants’ impact on herbivores and/or on the performance of EFN-bearing plants. A database compiling studies that fit these requirements was provided by Leal & Peixoto (2017) in a previous meta-analysis that evaluated the role of water availability in driving the effect of ant attendance on the performance of EFN-bearing plants. Although their objective was different from ours, their database was built following a replicable and detailed protocol suitable for searches focusing on studies investigating the role of ant attendance on EFN-bearing plants. Since Leal & Peixoto’s (2017) database included studies published in English between 1970 and September 2015, we updated this database by searching for new studies published between October 2015 and December 2019. For that purpose, we searched for papers in Scopus (www.scopus.com) and ISI Web of Knowledge (www.isiknowledge.com – core collection) databases, using the following key terms: “extrafloral nectar*”, “ant-plant mutualism”, “plant AND biotic defen*e”. These keywords and search sites were the same as used by Leal & Peixoto (2017). We found 25 new studies published in English for this new search, added to the 126 studies compiled by Leal & Peixoto (2017). After searching the literature, we screened the abstracts and methods of all papers to select the studies that fulfilled the following inclusion criteria: the studies must have (1) used plant species bearing natural EFNs as model organisms, discarding all the studies artificially manipulating EFN occurrence or extrafloral nectar availability to ants; (2) evaluated the role of ant attendance on plants by contrasting two groups of plants: one freely accessible by ant species (control group) and another group in which ants were naturally absent or experimentally excluded from plants; (3) used native plant species as a model to prevent confounding effects specific to invasive species (see Traveset & Richardson 2006); and (4) reported the sample size, the mean values, and the standard deviation or standard error for metrics related to herbivore performance or plant reproductive success in groups of plants in which ants were present or absent (see more information about these metrics below). After this screening, 38 studies remained in our database. However, we excluded from our dataset three studies that used as models two fern species: Pteridium aquilinum and Polypodium plebeium (Koptur et al 1998, Jones & Paine 2012, Rashbrook et al. 1992; see Table S2). Then, we created the dataset presented here, including 132 effect sizes from 35 studies undertaken in 31 different locations and using 42 EFN-bearing plant species belonging to 20 families of angiosperms as model species.