Positive species interactions shape species' range limits

Abstract

The relationship between niche and distribution, and especially the role of biotic interactions in shaping species' geographic distributions, has gained increasing interest in the last two decades. Most ecological research has focused on negative species interactions, especially competition, predation and parasitism. Yet the relevance of positive interactions – mutualisms and commensalisms – have been brought to the fore in recent years by an increasing number of empirical studies exploring their impact on range limits. Based on a review of 73 studies from a Web of Science search, we found strong evidence that positive interactions can influence the extent of species' geographic or ecological ranges through a diversity of mechanisms. More specifically, we found that while obligate interactions, and especially obligate mutualisms, tend to constrain the ranges of one or both partners, facultative positive interactions tend to widen ranges. Nonetheless, there was more variation in effects of facultative interactions on range limits, pointing to important context‐dependencies. Therefore, we propose that conceptual development in this field will come from studying ecological interactions in the context of networks of many species across environmental gradients, since pairwise interactions alone might overlook the indirect and environmentally‐contingent effects that species have on each other in communities of many interacting species. Finally, our study also revealed key data gaps that limit our current understanding of the pervasiveness of effects that positive interactions have on species' ranges, highlighting potential avenues for future theoretical and experimental work.

The geographic footprint of mutualism: How mutualists influence species' range limits

“…Out of the 57 studies of mutualist‐mediated niche modification at range limits, 23 (40%) present data consistent with range extension (Figure 2a) and 25 (44%) consistent with range constraint (Figure 2c) (Appendix S1: Table S2). Compared with range extension, range constraint is more frequent in mutualisms that are specialized and/or obligate (Appendix S1: Table S2), in line with the findings of Stephan et al (2021). The remaining studies are consistent with either no range effect (Figure 2d) (five studies; 9%) or range contraction (Figure 2b) (four studies; 7%).…”

“…The influence of mutualism on range limits has been alluded to in scattered case studies and theoretical models (Afkhami et al, 2014;Araújo & Rozenfeld, 2014;Godsoe et al, 2017). A recent review of such studies has called for a synthetic framework to organize and understand the mechanisms by which the broad spectrum of mutualistic interactions can affect range limits (Stephan et al, 2021). Such a framework is even more urgent as the planet undergoes rapid environmental change, causing the range limits of many species to shift (Cunze et al, 2013;Freeman et al, 2018;Sittaro et al, 2017).…”

Biotische interacties in aquatische ecosystemen

“…Door de sterke afhankelijkheid bij verplichte interacties zijn milieu-eisen van één van de soorten vaak bepalend voor het verspreidingsgebied van de andere partij in de interactie. Facultatieve interacties kunnen dit verspreidingsgebied juist vergroten (Stephan et al, 2021).…”

Global assessment of three Rumex species reveals inconsistent climatic niche shifts across introduced ranges

“…distributions in their (Bello et al, 2013), recent work has highlighted the importance of non-climatic factors, such as human disturbance, in introduced plant species distributions wski, 2015; Mairal et al, 2021;Pysek et al, 2010;Redpath & Rapson, 2015;Seebens et al, 2018). Biotic interactions can both restrict (Alexander et al, 2018;Bello et al, 2013;William Godsoe et al, 2018) and facilitate (Stephan et al, 2021) changes in niche shifts, but this is less likely to influence Rumex species as they do not rely upon pollinators, seed dispersers, or mycorrhiza (Cavers & Harper, 1964;Grime et al, 2007). Although they have escaped specialised herbivores in New Zealand this has not led to fitness differences or increased competitive ability (Costan, 2021).…”