Evolution on Islands: a colloquium to honor the careers of Daniel Crawford and Tod Stuessy
Jansen, Robert , Gruenstaeudl, Michael , Hawkes, Christine , Santos-Guerra, Arnoldo .
Phylogenetic relationships of Tolpis and Diversification between Plants and their Associated Arbuscular Mycorrhizal Fungi in Macaronesia.
Tolpis (Asteraceae) has been used as a model system in several investigations on the evolution of oceanic island plants. Its insular species were utilized in studies of artificial hybrid fertility, the validity of Baker's law, the application of DNA barcodes or the phylogenetic utility of microsatellites. Despite this considerable interest in Tolpis as a model genus, the phylogenetic history of the genus remains unresolved. Past investigations were unable to reliably resolve interspecific relationships,especially within the Canary Islands, where the genus is particularly diverse. Limited taxon sampling, the use of ambiguous outgroups and the use of popular but slowly-evolving plastid DNA markers limited resolution of relationships in the genus. We present a comprehensive molecular phylogeny of Tolpis by utilizing highly-variable nuclear DNA markers, a closely related outgroup and a comprehensive taxon set. Ribosomal as well as low-copy nuclear loci were utilized as DNA markers, combining high genetic variability with the ability to recover traces of reticulate evolution.Our results highlight the complexity of evolutionary history of Tolpis - a circumstance likely shared by many other island lineages: (a) the extant distribution of the genus was formed via two independent colonization pathways,(b) the genus has colonized archipelagoes multiple times, (c) its present insular diversity is the product of adaptive radiations, (d) species that nowadays inhabit different islands and different archipelagoes have once been in close enough proximity to have hybridized, (e) a re-colonization of the continent may have led to today's mainland taxa, and (f) several as-of-yet undescribed species await taxonomic recognition. We are currently sequencing complete plastid genomes for all species of Tolpis to develop an independent estimate of phylogenetic. Furthermore, we are using Tolpis todetermine relative importance of phylogenetic history, ecology, and geography for the evolution of plant-AM relationships. Based on our preliminary data, we conclude that there are non-random associations in arbuscular mycorrhizal fungi of Macaronesia. Three drivers of non-random AM formation, ecology, geography, and phylogeny, appear to have contributed to AM fungal diversification in these islands.
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1 - University Of Texas, Section Of Integrative Biology, Biological Laboratory 404, 2401 Whitis Avenue, Austin, TX, 78712, USA
2 - University Of Texas At Austin, Integrative Biology, 1 University Station C0930, Austin, TX, 78713, USA
3 - University Of Texas At Austin, Section Of Integrative Biology, 1 University Station C0930, Austin, TX, 78712
4 - Jardin de Aclimatacion de La Orotava, La Orotava, Tenerife, Spain
Presentation Type: Symposium or Colloquium Presentation
Location: Franklin A/Hyatt
Date: Wednesday, July 11th, 2012
Time: 10:45 AM