Effects of asymmetric dispersal on the coexistence of competing species

Abstract

The global biodiversity crisis has made a priority of understanding biodiversity maintenance in ecological communities. It is increasingly apparent that dispersal patterns can have important effects on such maintenance processes. Nevertheless, most competition theory has focused on a small subset of the possible dispersal patterns in nature. Here, we show that spatially asymmetric dispersal, i.e. the disproportionate transport of propagules towards or away from particular habitat patches in a metacommunity, when it differs between species, can promote the coexistence of competing species even in the absence of environmental heterogeneity among habitat patches. Moreover, when asymmetric dispersal is present, changes in the self-recruitment of competitive dominants and subordinates have important, but fundamentally different, effects on species coexistence. Our results underscore the importance of the interplay between species interactions and dispersal patterns for understanding the effects of habitat fragmentation and for designing regional-scale conservation strategies, such as networks of protected areas.

Larval dispersal drives trophic structure across Pacific coral reefs

“…Mounting evidence suggests that species' dispersal patterns shape community and food web structure in many ecosystems [38][39][40][41][42] . For example, competing reef fish species in the Great Barrier Reef ecosystem appear to have different dispersal abilities, and this difference may explain the complex patterns of species coexistence observed across the Great Barrier Reef 40 .…”

Different dispersal abilities allow reef fish to coexist

“…These factors include tidal patterns and oceanic currents (26)(27)(28) and the larvae's developing locomotive and sensory capabilities (23,(26)(27)(28). Dispersal is therefore highly variable, and both spatial (13,15) and temporal (9,11,28) variabilities interact to determine metacommunity dynamics and coexistence. In the second GBR example, we investigate whether species with different dispersal abilities can coexist in the presence of stochastic biophysical factors.…”

“…Interspecific dispersal differences can create ephemeral spatial niches in stochastic environments, and these are enough to allow species to coexist if their dispersal patterns are sufficiently uncorrelated (11). Alternatively, if two competing species have contrasting and asymmetric dispersal patterns, elevated levels of within-species competition can encourage the coexistence of the subordinate competitor (15). Finally, patchy dispersal behavior can increase the variety of coexisting species by decoupling the degree of spatial aggregation from the average dispersal distance (6,7).…”

“…Dispersal-focused coexistence theory typically represents the distribution of habitat patches either nonspatially (10,13,15) or as uniformly spaced linear or grid arrangements (6,10,11). In real ecosystems, however, patches are distributed irregularly through the landscape.…”

Upstream trophic structure modulates downstream community dynamics via resource subsidies

“…Previous work has shown that directionally biased movement of organisms can have significant effects on species coexistence (Levine, 2003;Lutscher, McCauley, & Lewis, 2007;Lutscher, Pachepsky, & Lewis, 2005;Salomon, Connolly, & Bode, 2010), metapopulation dynamics and stability (Elkin, Possingham, Michalakis, & DeAngelis, 2008;Wang, Haegeman, & Loreau, 2015), and metacommunity structure (Altermatt, Schreiber, & Holyoak, 2011;Bourgeois, González, Vanasse, Aubin, & Poulin, 2016;Dong et al, 2016). Mounting evidence now suggests that communities' dynamics can be indirectly coupled by the reciprocal spatial exchange of resources, even in the absence of dispersal of organisms (i.e., meta-ecosystem, Loreau, Mouquet, & Holt, 2003;Harvey, Gounand, Ganesanandamoorthy, & Altermatt, 2016).…”