Sun exposure drives Antarctic cryptoendolithic community structure and composition

Abstract

12 The harsh environmental conditions of the ice-free regions of Continental Antarctica are considered one of 13 the closest Martian analogues on Earth. There, rocks play a pivotal role as substratum for life and 14 endolithism represents a primary habitat for microorganisms when external environmental conditions 15 become incompatible with active life on rock surfaces. Due to the thermal inertia of rock, the internal 16 airspace of lithic substratum is where microbiota find a protected and buffered microenvironment, allowing 17 life to spread throughout these regions with extreme temperatures and low water availability. The high 18 degree of adaptation and specialization of the endolithic communities makes them highly resistant but 19 scarsely resilient to any external perturbation and thus, any shifts in microbial community composition may 20 serve as early-alarm systems of environmental perturbation, including climate change. 21 Previous research concluded that altitude and distance from sea do not play as driving factors in shaping 22 31 32 33 34

Endolithic Fungal Species Markers for Harshest Conditions in the McMurdo Dry Valleys, Antarctica

“…The effect of sunlight was also recently tested by a preliminary molecular survey, based on DGGE and qPCR techniques, of 48 rocks with north and south sun exposure, collected in Victoria Land along an altitudinal transect from 834 to 3100 m a.s.l. [52]. There, it has been found that differences in sun radiation influenced community composition and relative abundance of the three main biological compartments (fungi, algae and bacteria).…”

Metabolic responses in opposite sun-exposed Antarctic cryptoendolithic communities

“…The idea that untargeted mass spectrometry (MS)-based metabolomics analysis will result in a large list of 'identified' small molecules that can be mapped to networks and pathways is often assumed (Schrimpe-Rutledge et al, 2016). In this study, we considered rocks collected at opposite sun-exposure, accounted among the principal driving factor for settlement and shaping stress-response in cryptoendolithic life-style; indeed, recently, sun-exposure was found to be critical in shifting community composition, taxon abundance, and distribution of functional groups of fungi in Antarctic endolithic communities (Coleine et al, 2018b;Coleine et al, 2019a), affecting these ecosystems more than other abiotic parameters considered (e.g. altitude).…”