A Phylogeographic Study of Arenaria ciliata and Arenaria norvegica in Ireland and Europe

• Main Author: Howard-Williams, Emma
• Format: Thesis
• Language: English
• Published: 2013
• Subjects: Arctic; Ora; Svalbard; Tive
• Online Access: https://mural.maynoothuniversity.ie/6750/; https://mural.maynoothuniversity.ie/6750/1/EHW_PhD.pdf

The unusual distribution of Irish ora and fauna has intrigued and eluded biogeographers for centuries and remains the subject of ongo- ing debate. The conventional hypothesis for the postglacial coloniza- tion of Ireland across an Irish-British land-bridge has come under in- creasing scrutiny, with a growing body of evidence suggesting Ireland may have been a refugium during the last glacial cycle. In addition a strong affinity to Iberian populations is evident among much of the islands's native ora and fauna. This study focused on the disjunctly distributed arctic-alpine plant Arenaria ciliata, and its close arctic relative, A. norvegica, in an effort to characterise and date the earli- est links between Ireland and Continental Europe and to investigate the possibility for in situ survival of populations of these species in Ireland during the last glacial maximum. Twenty-nine populations of the target species were sampled through- out their range in Europe. Four separate chloroplast regions were sequenced: psbA-trnH, rpl32 -trnL, trnK -matK and matK, and the in- ternal transcribed spacer region of the nuclear ribosomal DNA (ITS). The chloroplast and ITS sequences were analyzed using maximum likelihood, haplotype networks, and a molecular clock analysis using Bayesian inference. Amplified fragment length polymorphism (AFLP) markers were generated for all populations sampled using three selec- tive primers and the obtained data were analysed using neighbour- joining analysis, networks, AMOVAs and direct analysis of the frag- ments. The results indicate a complex glacial history for these two species, where the consensus of the analysis demonstrates phylogeographic patterns indicative of Pleistocene glacial survival in situ, with evi- dence for cryptic refugia in Ireland, Rum and Svalbard, and multiple colonization events for A. ciliata. In contrast, the phylogeographic patterns obtained for A. norvegica are, for the most part, typical of a recent post-glacial expansion, with very low sequence divergence between ...