Molecular approaches in conservation and ecology research in marine sponges

Griffiths, Sarah Miriam (2018) Molecular approaches in conservation and ecology research in marine sponges. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

Marine ecosystems face a challenging future as a result of human activity, and as such, it is vital to understand the ecology of marine organisms in order to effectively conserve them. Increasingly, molecular ecology tools are used for this purpose. In this thesis, I developed molecular resources for the study of sponges, an ecologically important and diverse marine group. Firstly, I developed a bioinformatics pipeline for the de novo isolation of microsatellites - genetic markers used to study intraspecific genetic diversity. Using this method, I characterised microsatellites for two Tropical Western Atlantic sponge species, Ircinia campana and Spheciospongia vesparium. These species have suffered mass mortalities in Florida Bay (Florida Keys, USA), with devastating effects on the ecosystem, and are currently among the subjects of an ecological restoration program. With these microsatellites, I investigated the spatial genetic structure of populations of both species across the Greater Caribbean and within the Florida Keys. I found genetic isolation by distance patterns over the region, indicating distance-limited dispersal, and also identified oceanographic barriers to population connectivity. On smaller spatial scales, genetic structure was also present, but patterns of genetic patchiness suggested that stochastic processes were more influential in determining structure at this scale. Finally, I investigated the effect of the Ircinia campana genotype on the composition of its associated microbial community. I found that more genetically similar sponges hosted more similar microbiomes, supporting the theory of a close coevolutionary relationship, and highlighting the importance of genetic diversity within species. With these insights on the distribution and effects of genetic diversity, I discuss the implications for sponge restoration in Florida Bay, and make recommendations for conservation practitioners to ensure resilience in sponge populations.