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Abstract. Forty years ago, lichens were identified as extraordinary biological icenucleators (INs) that enable ice formation at temperatures close to0 ∘C. By employing INs, lichens thrive in freezing environmentsthat surpass the physiological limits of other vegetation, thus making themthe majority of vegetative biomass in northern ecosystems. Aerosolizedlichen INs might further impact cloud glaciation and have the potential toalter atmospheric processes in a warming Arctic. Despite the ecologicalimportance and formidable ice nucleation activities, the abundance,diversity, sources, and role of ice nucleation in lichens remain poorlyunderstood. Here, we investigate the ice nucleation capabilities of lichenscollected from various ecosystems across Alaska. We find ice nucleatingactivity in lichen to be widespread, particularly in the coastal rainforestof southeast Alaska. Across 29 investigated lichen, all species show icenucleation temperatures above −15 ∘C, and ∼30 %initiate freezing at temperatures above −6 ∘C. Concentrationseries of lichen ice nucleation assays in combination with statisticalanalysis reveal that the lichens contain two subpopulations of INs, similarto previous observations in bacteria. However, unlike the bacterial INs, thelichen INs appear as independent subpopulations resistant to freeze–thawcycles and against temperature treatment. The ubiquity and high stability ofthe lichen INs suggest that they can impact local atmospheric processes andthat ice nucleation activity is an essential trait for their survival incold environments.
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Molecular and phenotypic study put eastern North American Cetrelia in a global context of biogeography and phylogeny
Species of Cetrelia delimited based on chemical and morphological characters have been largely supported by subsequent phylogenetic analysis of molecular data. While a robust, taxonomically well sampled global phylogeny for Cetrelia exists, geographic sampling to date has focused on Europe and East Asia. Here we use extensive field, herbarium and laboratory study to examine the distributions and identities of the taxa occuring in eastern North America. The presence of three species in the region is confirmed with molecular data (C. chicitae, C. monachorum, C. olivetorum). While a fourth species (C. cetrarioides) also occurs based on phenotypic data; efforts to obtain sequences were unsuccessful. The subpopulations of Cetrelia species in the region have contrasting frequency and distribution patterns relative to disjunct European subpopulations. Quantification of frequency of Cetrelia occurrence compared to an index of habitat quality revealed that all species have a strong affinity to high quality habitats, reflecting broader connection between lichen species richness and disturbance found in numerous previous studies. The trends detected in Cetrelia are unlikely restricted to this genus and we suggest that large-scale detailed quantitative studies in local-scale occurrence over time are needed to address significant gaps in knowledge to advance lichen conservation.
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- Award ID(s):
- 2436848
- PAR ID:
- 10529788
- Publisher / Repository:
- American Bryological and Lichenological Society
- Date Published:
- Journal Name:
- The Bryologist
- Volume:
- 126
- Issue:
- 4
- ISSN:
- 0007-2745
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1639/0007-2745-126.4.461
