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Title: The origin, evolution and conservation of the Arran Sorbus microspecies
Author: Robertson, Ashley
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2000
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In theory, populations of agamospermous plants are genetically invariant and consequently hold little evolutionary potential. To test this hypothesis, molecular markers were used to examine evolutionary processes in the Sorbus microspecies S. pseudofennica and S. arranensis, which are endemic to the Isle of Arran, Scotland. The proposed hybrid origin of these microspecies was investigated using a variety of molecular markers. Two isozyme systems (AAT and 6PGD), a nuclear DNA marker and a chloroplast DNA marker all provided markers that were specific to the putative parental species, S. aucuparia and S. rupicola. These markers could not separate S. rupicola from S. aria (a potential parent), or fully distinguish between S. arranensis and S. pseudofennica. Individuals of both S. arranensis and S. pseudofennica were screened and results were compatible with these microspecies being derived from a cross between S. aucuparia and S. rupicola/S. aria. DNA sequences of the chloroplast trnL intron and trnL-trnF intergenic spacer for the Arran Sorbus microspecies were identical to those of S. aucuparia. In contrast, nucleotide substitutions were evident between the Sorbus microspecies and S. rupicola at three bases. Nuclear DNA markers (five microsatellites and a Rubisco intron primer pair) revealed variation among individuals within S. arranensis and S. pseudofennica microspecies. Only three S. arranensis clones were detected from a total of 179 individuals. In contrast eight clones were detected from a total of 140 S. pseudofennica individuals. Six families of S. arranensis and S. pseudofennica were screened with three nuclear DNA markers. No variation in banding pattern was found among any of the S. arranensis families. In contrast, segregation of molecular makes was found in three out of the six S. pseudofennica families.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available