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Abstract Detail

Bryology and Lichenology

Kaminsky, Barry [1], McDaniel, Stuart F. [2], Smith, Matthew [3].

You can't hide your lichenize: Infidelity in the Leptogium cyanescens species complex and its associated Nostoc.

Symbiosis, in which two or more organisms share scarce resources, is a ubiquitous but poorly understood phenomenon. How does selection in one organism favor alleles that benefit another unrelated organism? A classic example of a symbiosis is a lichen, which is formed from an intimate relationship between a fungus (mycobiont) and photosynthesizing partner (photobiont). Currently lacking is an understanding of the degree of specificity between mycobiont and photobiont genotypes. We expect that lichens that reproduce asexually will show high specificity, because the two genotypes will be co-inherited in isidia that contain both partners. In contrast, sexually reproducing lichens should show lower specificity, because the sexual spores contain only the fungus, and the symbiosis must be reestablished each generation. Here we utilized the common lichen Leptogium cyanescens sensu lato to assess the degree to which fungal host phylogeny predicts photobiont (cyanobacteria in the genus Nostoc) phylogeny. We sequenced three fungal genes (MCM7, RPB1, RPB2) and three photobiont genes (nifv1, rbclX, rpoc2). Within the Leptogium cyanescens species complex we found four distinct mycobiont clades and two photobiont clades. Three of the mycobiont species (Leptogium species B, C and D) formed a clade and associated with one clade Nostoc, meaning that the mycobiont speciation occurred without photobiont speciation. An AMOVA partitioned by mycobiont species versus locality showed that, amongst these three fungal species, the population structure of the photobiont is best explained by collection site rather than host species. We also found evidence of recombination within Leptogium sp. C and D, which showed that fungal spores are produced and may provide an opportunity for the mycobiont to form a lichen with a different Nostoc genotype. Leptogium species A was sister to the other clade, and associated with only the sister clade of photobionts, consistent with high specificity at this phylogenetic depth. These results highlight the dynamism of inter-species associations and the need to consider multiple phylogenetic scales in genealogical analyses of symbiosis.

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1 - University of Florida, Biology, PO Box 118525, Gainesville, Florida, 32611, USA
2 - University of Florida, Biology Department, Gainesville, FL, 32611, USA
3 - University Of Florida, Plant Pathology, PO Box 110680, Gainesville, FL, 32611-0680, USA


Presentation Type: Oral Paper
Session: 32, Bryology and Lichenology (ABLS) II
Location: 103/Savannah International Trade and Convention Center
Date: Tuesday, August 2nd, 2016
Time: 2:00 PM
Number: 32001
Abstract ID:500
Candidate for Awards:A. J. Sharp Award

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