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Title: Molecular markers in populations of the spiders Lepthyphantes tenuis and Enoplognatha ovata
Author: A'Hara, Stuart W.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1999
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Spiders (Arachnida: Araneae) are important polyphagous predators which limit pest numbers in arable crops. To utilise them fully as part of an IPM (integrated pest management) programme a greater understanding of basic population dynamics and ecology is required. Two species common to UK arable land: Lepthyphantes tenuis (Blackwall) and Enoplognatha ovata (Clerck) were studied. These species exhibit different rates of dispersal; the former a highly dispersive ballooning spider, the latter a more sedentary species - permitting the effect of dispersal on patterns of genetic variation to be examined. RAPD data were generated via 5 decamer primers and used to determine variation between and within populations at a local scale (<100 km). Individuals within a species showed a high degree of similarity calculated via the Nei and Li similarity coefficient (E. ovata >83% and L. tenuis >54%). Despite this high level of similarity, PCO (Principle Co-Ordinate) analysis detected a pattern within the similarity matrix which could be related to the geographical separation of the populations. A less obvious structure was detected by PCO analysis of L. tenuis samples. Further statistical analysis revealed that Fst estimates were higher, and heterozygosity levels lower, within E. ovata populations than L. tenuis populations emphasising the effect of dispersal and gene flow on reducing population structure. PCR-RFLP of a rDNA fragment containing ITS1 and 2 was carried out as an initial screen of variability with populations of L. tenuis from England, Scotland and New Zealand, and E. ovata populations from Dundee, Edinburgh and Elgin. Near identical RFLP patterns were found within a species. To investigate variation at the finest level, multiple ITS1 clones from one individual from each site were sequenced in both species. A total sequence variation of 2.7% was recorded across 10 E. ovata clones and 1.5% across 10 L. tenuis clones.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available