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Title: Phylogeography of two lusitanian sea stars
Author: Darrock, David John
ISNI:       0000 0004 2750 9536
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2010
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The first comprehensive genetic study of North East Atlantic and Mediterranean sea stars, Asterina gibbosa and Asterina phylactica, is presented here, based on mitochondrial DNA (mtDNA) and Amplified Fragment Length Polymorphism (AFLP) data. MtDNA analysis revealed that the two putative species are distinct however there is incomplete lineage sorting, with the two most common haplotypes being shared across both species. MtDNA revealed low divergence between populations especially among most Atlantic populations, with no significant differentiation between the two basins. Although, both species possessed private haplotypes within both basins, the most common haplotype within both species is found throughout the entire geographical range of both species. Two mitchondrial haplogroups were identified, both of which showed evidence for a population expansion, occurring during the Pleistocene epoch. Haplogroup 1 was dominated by A. gibbosa (88%) whereas haplogroup 2 was dominated by A. phylactica (84%). The mtDNA results tentatively suggest that one Asterina population may descend from a population that survived the last glacial maximum (LGM) in one or more northern refugium. The AFLP data showed that A. gibbosa and A. phylactica are genetically distinct, with no apparent hybridization between species, with the possible exception of a single individual found at Rovinj, Croatia which was identified as being an A. phylactica individual at the time of sampling, but the allocation test assigned it to the Naples, Italy, A. gibbosa population. This could be the result of introgression or the individual could have been incorrectly classified as A. phylactica at the time of sampling. The AFLP data showed that there is gene flow occurring but it appears to be restricted, particularly within the Mediterranean basin, with no apparent gene flow occurring between the Atlantic and Mediterranean basins. There was no evidence with either marker to conclude that the brooding behaviour of A. phylactica provides a different pattern of genetic diversity within populations or differentiation between populations to the crawl away behaviour of A. gibbosa. The analysis suggests that gene flow is slightly more restricted for A. phylactica than A. gibbosa and, for A. gibbosa, it is more restricted in the Mediterranean than the Atlantic. The study identifies both A. phylactica and A. gibbosa populations that would be suitable to receive conservation status, based upon their unique genetic characteristics.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available