The role of competition - colonization tradeoffs and spatial heterogeneity in promoting trematode coexistence

TitleThe role of competition - colonization tradeoffs and spatial heterogeneity in promoting trematode coexistence
Publication TypeJournal Article
Year of Publication2016
AuthorsMordecai E.A, Jaramillo A.G, Ashford J.E, Hechinger R.F, Lafferty K.D
Date Published2016/06
Type of ArticleArticle
ISBN Number0012-9658
Accession NumberWOS:000377219900012
Keywordsbiodiversity; bird final hosts; Carpinteria Salt Marsh; cerithidea-californica; Cerithideopsis californica; coexistence; community; competition - colonization tradeoff; larval trematodes; marine snail; parasite; population-dynamics; renicolid trematodes; spatial heterogeneity; species; trematode

Competition - colonization tradeoffs occur in many systems, and theory predicts that they can strongly promote species coexistence. However, there is little empirical evidence that observed competition-colonization tradeoffs are strong enough to maintain diversity in natural systems. This is due in part to a mismatch between theoretical assumptions and biological reality in some systems. We tested whether a competition - colonization tradeoff explains how a diverse trematode guild coexists in California horn snail populations, a system that meets the requisite criteria for the tradeoff to promote coexistence. A field experiment showed that subordinate trematode species tended to have higher colonization rates than dominant species. This tradeoff promoted coexistence in parameterized models but did not fully explain trematode diversity and abundance, suggesting a role of additional diversity maintenance mechanisms. Spatial heterogeneity is an alternative way to promote coexistence if it isolates competing species. We used scale transition theory to expand the competition - colonization tradeoff model to include spatial variation. The parameterized model showed that spatial variation in trematode prevalence did not isolate most species sufficiently to explain the overall high diversity, but could benefit some rare species. Together, the results suggest that several mechanisms combine to maintain diversity, even when a competition - colonization tradeoff occurs.

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