Ecography ECOG-01789 Bässler, C., Cadotte, M. W., Beudert, B., Heibl, C., Blaschke, M., Bradtka, J. H., Langbehn, T., Werth, S. and Müller, J. 2015. Contrasting patterns of lichen functional diversity and species richness across an elevation gradient. – Ecography doi: 10.1111/ ecog.01789 Supplementary material
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Ecography ECOG-01789 · dispersal (Ellis 2012). Ascomata size (mm²) The ascomata size is probably strongly related to dispersal capability. Large ascomata areas produce more spores.
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Ecography ECOG-01789Bässler, C., Cadotte, M. W., Beudert, B., Heibl, C., Blaschke, M., Bradtka, J. H., Langbehn, T., Werth, S. and Müller, J. 2015. Contrasting patterns of lichen functional diversity and species richness across an elevation gradient. – Ecography doi: 10.1111/ecog.01789
Supplementary material
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Appendix 1 1
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Table A1. Lichen traits used for the analysis and their possible functions. 3
Trait General life characteristics Thallus growth form/ size Thallus morphology has a strong impact on
physiological processes, water uptake and evaporation therefore determining the rate of photosynthesis activity (de Vries and Watling 2008, Sancho and Kappen 1989, Valladares 1994). This corresponds to the surface to volume ratio (e.g., Lakatos et al. 2006), respectively to the size of the thallus which is correlated with the thallus form (c.f. Johansson et al. 2007). Hence, the lichen thallus form has been attributed to basic ecological strategies (Rogers 1990) and proofed to be very sensitive to environmental changes (Ellis and Coppins 2006, Johansson et al. 2007) and was therefore often used as indicators (e.g., Giordani et al. 2012). For example, fruticose lichens were assigned to be competitors, while crustuse lichens seemed to be stress tolerant (Rogers 1990). Those crustose lichens with a cortex layer (dense glutinated hyphae) has been shown to be very less susceptible to mechanical damage but with high light absorptivity leading to effective exploitation of light under limited amounts of light (e.g., under a dense canopy, Pardow et al. 2010). Lichens act as an important habitat and diet source for animals (see Seaward 1977for an detailled overview). There is a high degree of specialization between insects or mammals and lichen species with a certain thallus growth form. Spatial pattern in lichen epiphyte growth forms for example appears to control invertebrate community composition (André 1985). Please note that the thallus form is correlated to thallus size and therefore to biomass (resource availability) of the species (Nash 2008). Large fruticose lichens for example act as important diet source for mammals (e.g., Rominger et al. 1996). Moreover, fruticose species of the genus Bryoria, Usnea are important for nest building (Brodo et al. 2001, Sharnoff and Rosentreter 1998).
Prothallus Contributes to the hydration status of (poikilohydric) lichens with a high water absorption capacity by acting as a sponge (Lakatos et al. 2006).
Photobiont The lichen photobionts have different characteristics facilitating the lichen species to cope with specific environmental conditions (Palmqvist 2000): Green algae from the genus Trentepholia and Trebouxia (green algae) ensure photoprotection (dissipate excess excitation energy in chlorophyll into heat under light stress, Gauslaa and Solhaug 1996). Moreover, green algae are less sensitive to a low level of humidity (Honegger 1991). Lichens with
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photobionts from the genus Trentepholia for example facilitate development at higher levels of temperature (Aptroot and van Herk 2006) and allows to exist in shady habitats (Friedl and Büdel 1996). Cyanobacteria acting as photobionts on the other hand are able to fix nitrogen (N2) from the atmosphere (Palmqvist et al. 2002). They furthermore use a wide part of light spectrum using phycobilisomes as light-harvesting antennae (Rikkinen 2009) broadening the range of usable habitats. Species with cyanobacteria as a photobiont partner furthermore are able to develop after prolonged exposure to high irradiance (Giordani et al. 2014).
Secondary metabolism About 1,050 lichen substances are known and studies suggest that many of them impact biotic and abiotic interactions of lichens (reviewed in Molnar and Farkas, 2010): They may help to protect the thalli against herbivores, pathogens, competitors and external abiotic factors, such as high UV irradiation (see also Honegger 1993). Many of them exhibit multiple biological activities, such as the dibenzofuran usnic acid (e.g., antimicrobial and larvicidal effects, anticancer activities, known also for its UV-absorption). High potential for the use as pharmaceutical (see e.g., Ari et al. 2015, Mueller 2001).
the ecological amplitude of the species (Bowler and Rundel 1975, Hale 1967). The production of soredia and isida seem an adaption to environmental stress (Marshall 1996, Smith, 1984). Studies furthermore suggest that establishment on resources is facilitated by asexual propagules (at the cost of dispersal – trade-off, see e.g. Ellis 2012). Species with isidia across the thallus have a higher photosynthetic rate because of the very low CO2 saturation point related to the high surface to volume ratio (Tretiach et al. 2005). Species with soredia were defined as stress tolerant species (Rogers 1990).
Conidia Production of conidia can be observed in many members of the ascomycetes (Carlile et al. 2001). The production of conidia might contribute to the dispersal capability but with a limited investment by the lichen. The production of conidia therefore might be a compromise between the costly sexual reproduction leading to haploid spores through meiosis with a potential for long distance dispersal (Lacey 1996) and the production of large asexual propagules (e.g. isidia) consisting of both the myco- and the phytobiont but with a limited range of dispersal (Ellis 2012).
Ascomata size (mm²) The ascomata size is probably strongly related to dispersal capability. Large ascomata areas produce more spores. If spore size is critical for dispersal and establishment (Halbwachs and Bässler 2015, Norros et al. 2014, see below), species with a large ascomata area can optimize both, the number and size of spores
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(see e.g. Bässler et al. 2014 for fungi).
Spore volume (µm³) Although fungal spores are tiny compared to plant seeds, the range in size is considerable which suggests selective forces and different ecological strategies (Halbwachs and Bässler 2015). Numbers of studies hence points towards the size of spores to have a high relevance in terms of dispersal and establishment: Generally, due to their small size, sexual spores can be trapped even on smooth surfaces (Giordani et al. 2012). Advantages of large spores:
• Large spores can contain more carbon and nutrients (Carlile et al. 2001, Deacon 2005, Hawker, and Madelin 1976, Sanders and Lucking 2002); may more easy germinate under nutrient-limited conditions.
• Show prolonged dormancy (Carlile et al. 2001, Deacon 2005).
• Might lead to a better establishment (see also asexual propagules, Sanders and Lucking 2002); to strike, e.g. tree trunks (Tulloss 2005) with a high impaction efficiency (Hawker and Madelin 1976).
Advantages of small spores:
• Increased colonization rates (Johansson et al. 2012).
• Small spores fly farther and better circumvent obstacles (Norros et al. 2014, Tulloss 2005).
• They may be more easily blown around obstacles than large spores, which is advantageous in habitats with scattered substrates or hosts (Tulloss 2005).
Spore shape Advantages of oblong spores:
• Rotate during air dispersal and thereby travel farther and improve substrate impact (Ingold 1965).
• Narrow spores in the fungal genus Amanita occur in dry and/or low-nutrient habitats and in habitats with short growing seasons, such as northern bogs and heaths (Tulloss 2005).
Advantages of globose spores:
• Globose spores expose the least possible surface to a potentially harmful environment (Carlile et al. 2001).
Spore pigmentation Pigmented, melanised spores are better protected
against UV-radiation during dispersal (Durrell 1964, Vellinga 2004), desiccation (Zhdanova et al. 1980), high and low temperatures (Rehnstrom and Free 1996), and enzymatic and microbial attacks (Kuo and Alexander 1967) than hyaline spores. In addition, melanins contribute to the mechanical stability of the spore (Cooke and Whipps 1993), allowing air-
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dispersed spores to survive long distances and exposure at impact site. Strongly correlated with wall thickness and hence interpreted as an important trait syndrome underpinning these possible adaptions (Halbwachs and Bässler 2015, Halbwachs et al. 2015). In contrast, hyaline spores (in combination with thin walls) germinate quickly in habitats with short growing seasons and were interpreted as an adaption for a rapid development (Sanders and Lucking 2002).
Spore septation Cell aggregates with increased chance of germination by the process of subdivision (germination insurance) (Pentecost 1981). The spore might be stabilized by the septates (Pentecost 1981) thereby optimizing spore size (see above) independent from spore wall thickness. Such a trait syndrome would improve successful establishment (large spore) and immediate germination (thin spore wall, Halbwachs et al. 2015)
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