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Bryological and Lichenological Section/ABLS

Nelsen, Matthew P. [1], Gargas, Andrea [1].

Photobiont diversity and fungal specificity in the lichen genera Lepraria and Thamnolia.

Lepraria and Thamnolia both reproduce vegetatively (via soredia and thallus fragmentation, respectively) with ascocarps and pycnidia being absent. Consequently, the relationship between symbionts might be expected to be quite stable, with these genera showing high specialization for their algal partners and utilizing monophyletic groups of algae. Instead, we show Lepraria associates with several clades of algae in the genus Asterochloris (sensu Friedl), while Thamnolia uses several lineages of the algal genus Trebouxia (in 3 of the 4 major clades). For both fungal groups, monophyly of algal symbionts is rejected, suggesting symbiont switching, a trend sometimes seen among vertically transmitted symbioses. Photobiont specificity of Thamnolia vermicularis is assessed, and it is found to be a generalist. Fungal phylogenies were also estimated and compared with the algal trees, revealing a lack of strict codiversification in both lichen genera. Additionally, monophyly of the individual Thamnolia chemotypes (baeomycesic and squamatic acid vs. thamnolic acid) is rejected, instead showing the two are intermixed. Our study provides further evidence that having a predominantly shared mode of dispersal does not necessarily lead to codiversification or the maintenance of a stable relationship between symbionts.

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1 - University of Wisconsin Madison, Department of Botany, Birge Hall, 430 Lincoln Drive, Madison, Wisconsin, 53706-1381, USA

Lepraria, Thamnolia, photobiont.

Presentation Type: Oral Paper
Session: 15-3
Location: Salon A - Gov Ballroom/Hilton
Date: Monday, August 15th, 2005
Time: 2:00 PM
Abstract ID:370

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