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Title: Biodiversity of freshwater sponges (Porifera: Spongillidae) in the UK : taxonomy, distribution, and ecology
Author: Evans, K. L.
ISNI:       0000 0004 6058 9937
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2016
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Specimens of freshwater sponges (Porifera: Spongillidae), one of the most poorly known faunal groups in the UK, were obtained from natural (lentic and lotic) habitats and from anthropogenic (canal) habitats. The investigations encorporated a multidisciplinary approach to address questions of species diversity, species distribution, abundance, key water parameters, spicule variability, sequence divergence, and molecular and morphological taxonomy. A total of six species of sponges were identified (Spongilla lacustris, Ephydatia fluviatilis, Ephydatia mülleri, Eunapius fragilis, Racekiela ryderii) including a species new to the UK: Trochospongilla horrida. The morphology, taxonomy, distribution, and ecology of each species were examined. A taxonomic key to UK species of freshwater sponges was presented. New limits of tolerance to water parameters were established for species. An analysis of a partial COI mtDNA gene sequences was conducted to determine variation within and between freshwater sponge species, and was followed with an analysis of marine species. The resolution power of the COI gene was compared with 28S rDNA and ITS rDNA sequence data from UK freshwater sponge species. Low variability of COI gene sequences was found, with low nucleotide diversity, suggesting a high conservation of mtDNA in sponges. Populations of a common and widely distributed species (Spongilla lacustris) were investigated to assess increased spicule size in habitats with low dissolved phosphorus and increased pH. Populations of a rare UK species, with an amphiatlantic distribution (Racekiela ryderii) were investigated to assess spicule variability and evidence of a 'form' called pictovensis. However, insufficient genetic variability in COI and ITS genes were observed within this species supporting the inclusion of the pictovensis form into the species R. ryderii. An integrated approach using genetic and morphological characteristics to identify sponge species identification was suggested. Both genetic sequence data together with morphology provided valuable taxonomic insights and contributed to the formation of an integrated picture of biodiversity in natural and anthropogenic UK freshwater habitats.
Supervisor: Montagnes, D. ; Watts, P. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral