Abstract
The Atacama Desert is one of the driest and probably oldest deserts on Earth where only a few extremophile organisms are able to survive. This study investigated two terricolous and two epiphytic lichens from the fog oasis “Las Lomitas” within the National Park Pan de Azúcar which represents a refugium for a few vascular desert plants and many lichens that can thrive on fog and dew alone. Ecophysiological measurements and climate records were combined with molecular data of the mycobiont, their green algal photobionts and lichenicolous fungi to gain information about the ecology of lichens within the fog oasis. Phylogenetic and morphological investigations led to the identification and description of the new lichen species Acarospora conafii sp. nov. as well as the lichenicolous fungi that accompanied them and revealed the trebouxioid character of all lichen photobionts. Their photosynthetic responses were compared during natural scenarios such as reactivation by high air humidity and in situ fog events to elucidate the activation strategies of this lichen community. Epiphytic lichens showed photosynthetic activity that was rapidly induced by fog and high relative air humidity whereas terricolous lichens were only activated by fog.
Highlights
The Atacama Desert in South America represents the driest place and the oldest desert on Earth and has experienced extreme hy‐ peraridity for at least 3 million years (Hartley, Chong, Houston, & Mather, 2005)
This was demonstrated for lichens from the coastal fog zone of the Namib Desert, where these lichens with the highest surface to volume ratio reached the highest photo‐ synthesis rates and made most effective use of different water sources (Lange, Meyer, Ullmann, & Zellner, 1991)
Since terricolous lichens have been recently reported to show a large range of adaptations and rapid responses to their environment (Green, Pintado, Raggio, & Sancho, 2018), the present study aims to compare and describe the eco‐ physiological patterns of the two most abundant terricolous and epiphytic lichens of an isolated lichen community
Summary
The Atacama Desert in South America represents the driest place and the oldest desert on Earth and has experienced extreme hy‐ peraridity for at least 3 million years (Hartley, Chong, Houston, & Mather, 2005). The occurrence of fog at Las Lomitas creates a narrow ecological niche for the establishment of at least some vascular plants with a very low coverage which is com‐ posed mainly of a few cacti and Euphorbia shrubs Both length and intensity of fog events is highly variable resulting in a wide range of daily water inputs that can reach up to 16.6 mm precipitation avail‐ able for lichens on a single day (Lehnert, Thies, et al, 2018). Fog interception should not be confused with conden‐ sation (Villegas, Tobón, & Breshears, 2008) as it is comparable to filter feeding by aquatic invertebrates (Larson, 1981; Stanton & Horn, 2013), and seems to be related to lichen growth form (Lange & Redon, 1983; Stanton, 2015) This was demonstrated for lichens from the coastal fog zone of the Namib Desert, where these lichens with the highest surface to volume ratio reached the highest photo‐ synthesis rates and made most effective use of different water sources (Lange, Meyer, Ullmann, & Zellner, 1991). The mycobiont and photobiont of the examined lichens, as well as their specific lichenicolous fungi, are sequenced with a multi gene loci approach in order to elucidate their taxonomic identity
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