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Title: Population structure and species delimitation of Zoanthidea
Author: Burnett, W. J.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1995
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Zoanthidea (Cnidaria, Anthozoa, Hexacorallia) are common on tropical rocky shores and coral reefs. Large numbers of nominate species exist and many are difficult to identify. I used a genetic approach to examine population structure and taxonomy of zoanthids from the Great Barrier Reef and Torres Strait regions of Australia. Genetic population structure was investigated over two different spatial scales, using allozyme electrophoresis at seven polymorphic loci. I collected Palythoa caesia samples from 20 reefs spread over 1800 km. Results show that genetic differentiation among reefs is low but statistically significant, primarily due to variation in two populations. Population structure is characterised by genetic patchiness against a background of high gene flow. In a second study I collected Zoanthus coppingeri samples from three localities. Populations show evidence of asexual reproduction but are not dominated by successful clones. Sites separated by 50 m are genetically differentiated. Gene flow prevents fixed gene differences arising among populations of both these species. Fixed differences in taxonomic surveys (below) are therefore strong indicators of species boundaries. Eight species, from 19 localities throughout the Great Barrier Reef and Torres Strait, were genetically delimited using allozyme analysis of 14 loci. These species are separated by fixed gene differences. Genotype frequencies within species conform to Hardy-Weinberg predicted ratios. There is considerable morphological variation within species. Five species are identified in the family Zoanthidae: Palythoa caesia, Protopalythoa mutuki, Sphenopus marsupialis, Zoanthus coppingeri and Z. vietnamensis. These are probable senior synonyms of eighteen nominate species. Two Protopalythoa species remain unidentified. The eighth species, Parazoanthus dichroicus, is in the Parazoanthidae. A key to species is given. Phylogenetic analysis of zoanthid species used allozyme data and sequence data from 28S rDNA. I discuss results in the light of previous views of zoanthid systematics.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available