At Limits of Life: Multidisciplinary Insights Reveal Environmental Constraints on Biotic Diversity in Continental Antarctica

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From: PLoS ONE(Vol. 7, Issue 9)
Publisher: Public Library of Science
Document Type: Report
Length: 7,371 words
Lexile Measure: 1610L

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Author(s): Catarina Magalhães 1 , * , Mark I. Stevens 2 , S. Craig Cary 3 , 8 , Becky A. Ball 4 , Bryan C. Storey 5 , Diana H. Wall 6 , Roman Türk 7 , Ulrike Ruprecht 7

Introduction

The evolutionary and biogeographic history of the Antarctic cold-desert biota reveals many components of ancient origin [1], [2]. Long-term isolation of this biota implies persistence through multiple glacial cycles [3], [4]. However, few have attempted to resolve the critical requirements for life that maintain the southern most functioning terrestrial ecosystems with the simplest and lowest diversity food web of any natural community. Organisms that survive in these extremely cold and arid Antarctic terrestrial ecosystems are subject to more environmental stresses than any other desert on the planet; dramatic physical and chemical gradients combined with extreme conditions including low temperatures, low available water and humidity, abundant freeze-thaw cycles, high salinity, low carbon and nutrient concentrations and high ultra-violet radiation [5], [6], [7], [8], [9].

Continental Antarctic soils are usually described as biologically depauperate and very simple in terms of biological diversity and food webs, since it is usually accepted that as the environmental constraints increase, fewer organisms possess the necessary adaptations [8], [9]. Faunal terrestrial communities of continental Antarctic ecosystems consist largely of simple communities of invertebrates: springtails, mites, nematodes, rotifers and tardigrades [12]. Only the vegetation forming organism, such as algae, lichen and moss occur at these extreme conditions [12], [13]. Microbial communities in Antarctic soils have received comparatively less attention in this respect, as it was previously suggested that these extreme ecosystems exhibit low diversity and abundance [14], [15]. However, contrary to earlier assumptions, recent studies based on culture-independent genetic tools are now discovering that these ecosystems contain highly diverse microbial communities [7], [16], [17], [18], [19], [20]. The trophic simplicity of Antarctic ecosystems offers a great and unique opportunity to address questions related to biodiversity, trophic relationships, succession and ecosystem functionality, and ultimately the constraints to each of these elements [7], [12].

The distribution and abundance of the Antarctic biota are subject to high spatial patterning due to the extreme heterogeneity of biogeochemical properties and climate gradients [6], [16], causing important selection pressures on micro and macrobiota distribution [6], [16], [21], [22], [23], [24]. Thus, knowing which environmental factors drive the distribution of species at different trophic levels is essential to understand ecosystem dynamics of polar terrestrial environments [16]. Studies on the environmental factors that drive habitat suitability for multitrophic community establishment, for example in the McMurdo Dry Valleys, have revealed that soil chemistry is a primary driver for establishment of soil biota [6], [16], [21], [22], [23]. Other studies have suggested that the source and composition of organic matter, availability of liquid water, and soil salinity impose strong limitations over biological colonization [23], [25], [26], [27].

Previous research on micro and macro-biotic distribution has been conducted in Antarctic extreme cold desert environments, mainly in the Victoria Land region [6], [7], [12], [18], [19], [28], [29],...

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Gale Document Number: GALE|A498262151