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Abstract Detail

Bryology and Lichenology

Widhelm, Todd [1], Bertoletti, Francesca [2], Asztalos, Matt [2], Moncada, Bibiana [3], Lücking, Robert [4], Serusiaux, Emmanuel [5], Goffinet, Bernard [6], Lumbsch, Thorsten [2].

Miocene radiation and drivers of diversification in the genus Sticta (Lobariaceae).

The genus Sticta includes foliose lichens with green algal and/or cyanobacterial photosynthetic partner and is widely distributed in tropical and oceanic habitats. Recent studies indicate a high species diversity and restricted geographical ranges. We assembled a data set of 224 samples and five molecular markers to study the diversification of the genus. Using secondary fossil calibrations and rates of molecular evolution, we estimated divergence times in Sticta. Our analyses suggest that Sticta and Pseudcyphellaria diverged from a common ancestor in the Oligocene, nearly 30 million years ago and diversified into five major clades during the Miocene and Pliocene epochs. Binary state speciation and extinction (BiSSE) analyses were conducted to investigate the effect of primary photobiont on the diversification of the major clades in Sticta. The BiSSE analysis found higher rates of speciation in taxa that primarily associate with Nostoc (state "0"; 92 species) compared to taxa mostly associating with green algae (state "1"; 23 species). However, the BiSSE results were misleading, as 500 iterations of randomized state assignments (maintaining the same ratio of 92 Nostoc to 23 green algae) found the 118-tip tree and the large tip ratio bias confounding to the results. Each iteration recovered higher speciation rates in Nostoc-associating species no matter the state assignment on the tips of the phylogeny. Furthermore, transition rates between states were found to be equal (q01 = q10), which may be due to the presence of photosymbiodemes in Sticta. Further sampling throughout the range may discover that Sticta has more photosymbiodemic species than we currently estimate.

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1 - Field Museum, 1400 S. Lake Shore Drive, Chicago, Illinois, 60605, United States
2 - The Field Museum, Science & Education, 1400 S. Lake Shore Drive, Chicago, IL, 60605, USA
3 - Universidad Distrital Francisco José de Caldas, Herbario, Bogotá, Colombia
4 - Botanischer Garten und Botanisches Museum, Herbarium, Königin-Luise-Straße 6-8, Berlin, 14195, Germany
5 - University of Liège, Evolution and Conservation Biology, Liège, Belgium
6 - University of Connecticut, ECOLOGY AND EVOLUTIONARY BIOLOGY, Storrs, CT, USA

none specified

Presentation Type: Oral Paper
Session: 28, Bryology and Lichenology (ABLS) II
Location: Sundance 1/Omni Hotel
Date: Tuesday, June 27th, 2017
Time: 2:15 PM
Number: 28004
Abstract ID:63
Candidate for Awards:A. J. Sharp Award

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