Contributions of Mutualisms to Setting Species' Range Limits

May 08, 2023 | 1 Minute Read

Species' range limits are usually explained by climatic and antagonistic biotic interactions that limit the ability of species to persist beyond the range edge. Mutualistic interactions have the potential to ease these limitations, and this potential has been only rarely examined. Mutualisms are often context-dependent, which makes predicting their outcome across different environments challenging. Mutualisms may extend a range limit by improving population performance at and beyond the range edge, but these benefits depends on the prevalence of the interaction, the effect of the interaction, and the sensitivity of the host to the interaction. There are many ways in which mutualisms may be context-dependent, and range limits are often found along complex environmental gradients. See a review of these mechanisms published in Ecological Monographs here.

By using demographic field experiments, we can assess the mechanisms by which the mutualism contributes or does not contribute to the range limit. I have established a seedling transplant experiment with endophyte-infected grasses to quantify the contribution of mutualisms to population growth across range limits for three common, Eastern U.S. grasses.