Abstract
Theories and empirical evidence suggest that random dispersal of organisms promotes species coexistence in spatially structured environments. However, directed dispersal, where movement is adjusted with fitness-related cues, is less explored in studies of dispersal-mediated coexistence. Here, we present a metacommunity model of two consumers exhibiting directed dispersal and competing for a single resource. Our results indicated that directed dispersal promotes coexistence through two distinct mechanisms, depending on the adaptiveness of dispersal. Maladaptive directed dispersal may promote coexistence similar to random dispersal. More importantly, directed dispersal is adaptive when dispersers track patches of increased resources in fluctuating environments. Coexistence is promoted under increased adaptive dispersal ability of the inferior competitor relative to the superior competitor. This newly described dispersal-mediated coexistence mechanism is likely favored by natural selection under the trade-off between competitive and adaptive dispersal abilities.
Highlights
Species dispersal plays important roles in biodiversity patterns observed in nature [1]
Explicit models describe the demographic processes in local patches, and theory predicts that random dispersal promotes species coexistence via two mechanisms different from competition-colonization trade-offs i.e., ‘‘source-sink coexistence’’ and ‘‘emigration-mediated coexistence’’ [5,11,12,13,14,15]
Armsworth and Roughgarden [36] and Amarasekare [19] focused on adaptive fitness-dependent dispersal; the results indicated the adaptive dispersal did not promote species coexistence
Summary
Species dispersal plays important roles in biodiversity patterns observed in nature [1]. Dispersal facilitates coexistence of competing species that otherwise might not coexist [2,3] One mechanism of this ‘‘dispersal-mediated coexistence’’ is based on competition-colonization trade-offs [4,5,6,7]. Animal dispersal sometimes occurs at the same timescale as demographic processes [2] Under these conditions, explicit models describe the demographic processes in local patches, and theory predicts that random dispersal promotes species coexistence via two mechanisms different from competition-colonization trade-offs i.e., ‘‘source-sink coexistence’’ and ‘‘emigration-mediated coexistence’’ [5,11,12,13,14,15]
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