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Invasive habitat-forming ecosystem engineers modify the abiotic environment and thus represent a major perturbation to many ecosystems. Because native species often persist in these invaded habitats but have no shared history with the ecosystem engineer, the engineer may impose novel selective pressure on native species. In this study, we used a phenotypic selection framework to determine whether an invasive habitat-forming ecosystem engineer (the seaweed Caulerpa taxifolia) selects for different phenotypes of a common cooccurring native species (the bivalve Anadara trapezia). Compared to unvegetated habitat, Caulerpa habitat has lower water flow, lower dissolved oxygen, and sediments are more silty and anoxic. We determined the performance consequences of variation in key functional traits that may be affected by these abiotic changes (shell morphology, gill mass, and palp mass) for Anadara transplanted into Caulerpa and unvegetated habitat. Both linear and nonlinear performance gradients in Anadara differed between habitats, and these gradients were stronger in Caulerpa compared to unvegetated sediment. Moreover, in Caulerpa alternate phenotypes performed well, and these phenotypes were different from the dominant phenotype in unvegetated sediment. By demonstrating that phenotype–performance gradients differ between habitats, we have highlighted a role for Caulerpa as an agent of selection on native species.

Item Type:	Refereed Article
Keywords:	bivalve, ecosystem engineers, hypoxia, invasive species, marine algae, performance, phenotypic selection, plasticity, selection gradient analysis
Research Division:	Biological Sciences
Research Group:	Ecology
Research Field:	Marine and Estuarine Ecology (incl. Marine Ichthyology)
Objective Division:	Environment
Objective Group:	Flora, Fauna and Biodiversity
Objective Field:	Antarctic and Sub-Antarctic Flora, Fauna and Biodiversity
Author:	Wright, JT (Dr Jeffrey Wright)
ID Code:	81209
Year Published:	2012
Web of Science® Times Cited:	14
Deposited By:	NC Marine Conservation and Resource Sustainability
Deposited On:	2012-11-27
Last Modified:	2017-10-31
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