Ant-mediated seed dispersal in a warmed world

PeerJ. 2014 Mar 11:2:e286. doi: 10.7717/peerj.286. eCollection 2014.


Climate change affects communities both directly and indirectly via changes in interspecific interactions. One such interaction that may be altered under climate change is the ant-plant seed dispersal mutualism common in deciduous forests of eastern North America. As climatic warming alters the abundance and activity levels of ants, the potential exists for shifts in rates of ant-mediated seed dispersal. We used an experimental temperature manipulation at two sites in the eastern US (Harvard Forest in Massachusetts and Duke Forest in North Carolina) to examine the potential impacts of climatic warming on overall rates of seed dispersal (using Asarum canadense seeds) as well as species-specific rates of seed dispersal at the Duke Forest site. We also examined the relationship between ant critical thermal maxima (CTmax) and the mean seed removal temperature for each ant species. We found that seed removal rates did not change as a result of experimental warming at either study site, nor were there any changes in species-specific rates of seed dispersal. There was, however, a positive relationship between CTmax and mean seed removal temperature, whereby species with higher CTmax removed more seeds at hotter temperatures. The temperature at which seeds were removed was influenced by experimental warming as well as diurnal and day-to-day fluctuations in temperature. Taken together, our results suggest that while temperature may play a role in regulating seed removal by ants, ant plant seed-dispersal mutualisms may be more robust to climate change than currently assumed.

Keywords: Ants; Climate change; Myrmecochory; Seed dispersal; Warming.

Grants and funding

Funding was provided by the US Department of Energy PER (DE-FG02-08ER64510) and US National Science Foundation (NSF 1136703) to N Sanders and R Dunn, and DOE Climate Science Center Award and an NSF Career Award to R Dunn (NSF 09533390). K Stuble was supported by an EPA STAR and funds from the Department of Ecology and Evolutionary Biology at the University of Tennessee. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.