Effects of Anthropogenic Disturbances on Diaspore Removal by Ants: A Meta-Analysis

Anthropogenic changes in natural landscapes are identified as a major driver of biodiversity loss worldwide. Consequently, important ecosystem functions, such as seed dispersal by animals, can be lost, which threaten the stability of essential ecological processes. Given the current scenario of large seed disperser's loss, secondary dispersal by ants has been identified as an important alternative to mitigate the impacts caused by human changes. However, empirical evidence shows contradictory effects of anthropogenic disturbances on diaspore removal by ants. Here, we conducted a global meta-analysis from 22 studies (65 comparisons) comparing diaspore removal by ants in disturbed versus preserved areas to investigate general trends to different anthropogenic disturbances. Specifically, we evaluate: (i) the effects of anthropogenic disturbances on diaspore removal by ants comparing temperate and tropical regions, and (ii) comparing different disturbance types (agriculture related disturbances, fragmentation, mining, fire, etc.) on diaspore removal by ants. We found an overall negative effect of anthropogenic disturbances on diaspore removal by ants (26% decrease), both in temperate and tropical regions (38% and 19% decrease, respectively). In addition, diaspore removal by ants responded negatively to disturbances related to fragmentation (24% decrease) and mining (83% decrease). However, we found no evidence of effects in areas subjected to agricultural processes (0.9% decrease). Our findings suggest that human disturbances might compromise crucial early stages to the natural regeneration in ecosystems such the seed dispersal.