THE EVOLUTIONARY ECOLOGY OF THE NON-NATIVE SEAWEED Gracilaria vermiculophylla AND ITS ASSOCIATION WITH THE NATIVE DECORATOR POLYCHAETE Diopatra cuprea
Kollars, Nicole Marie
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Case-studies on non-native species provide insight into mechanisms underlying invasion success and the consequences of species introductions to biological communities and ecosystems. My thesis uses field, laboratory, and molecular approaches to investigate the evolutionary ecology of the non-native, red seaweed <italic> Gracilaria vermiculophylla </italic> (hereafter <italic> Gverm </italic>). The first chapter describes a mutualism formed between <italic> Gverm </italic> and the native decorator polychaete <italic> Diopatra cuprea </italic> (hereafter <italic> Diopatra </italic>). Field surveys and experimental manipulations showed that <italic> Diopatra </italic> facilitates <italic> Gverm </italic> by anchoring the seaweed in a favorable photic zone for growth while <italic> Gverm </italic> reciprocally benefits <italic> Diopatra </italic> largely through nutritional provision. However, the net fitness outcome of the interaction for both species was variable. Chapter one concludes that the facilitation of <italic> Gverm </italic> by <italic> Diopatra </italic> is driving the invasion of <italic> Gverm </italic> to southeastern estuaries and further supports the hypothesis that positive species interactions can enhance invasion success. The second chapter describes microsatellite markers designed to investigate the invasive history of <italic> Gverm </italic>. Nine polymorphic loci were identified from a library of contigs developed using 454-next generation sequencing. The markers exhibited two to ten alleles, showed single-locus genetic determinism, and distinguished ploidy and genetic clones. Consequently, these markers will serve as effective genetic fingerprinting tools for <italic> Gverm </italic>. The combined efforts of my thesis advance our understanding of both the ecology and evolutionary history of the <italic> Gverm </italic> invasion with broader applications to the study of mutualisms and seaweed genetic diversity.