The spatial structure of Antarctic biodiversity

Abstract

Patterns of environmental spatial structure lie at the heart of the most fundamental and familiar patterns of diversity on Earth. Antarctica contains some of the strongest environmental gradients on the planet and therefore provides an ideal study ground to test hypotheses on the relevance of environmental variability for biodiversity. To answer the pivotal question, “How does spatial variation in physical and biological environmental properties across the Antarctic drive biodiversity?” we have synthesized current knowledge on environmental variability across terrestrial, freshwater, and marine Antarctic biomes and related this to the observed biotic patterns. The most important physical driver of Antarctic terrestrial communities is the availability of liquid water, itself driven by solar irradiance intensity. Patterns of biota distribution are further strongly influenced by the historical development of any given location or region, and by geographical barriers. In freshwater ecosystems, free water is also crucial, with further important influences from salinity, nutrient availability, oxygenation, and characteristics of ice cover and extent. In the marine biome there does not appear to be one major driving force, with the exception of the oceanographic boundary of the Polar Front. At smaller spatial scales, ice cover, ice scour, and salinity gradients are clearly important determinants of diversity at habitat and community level. Stochastic and extreme events remain an important driving force in all environments, particularly in the context of local extinction and colonization or recolonization, as well as that of temporal environmental variability. Our synthesis demonstrates that the Antarctic continent and surrounding oceans provide an ideal study ground to develop new biogeographical models, including life history and physiological traits, and to address questions regarding biological responses to environmental variability and change.

Passive warming reduces stress and shifts reproductive effort in the Antarctic moss,Polytrichastrum alpinum

“…3) (although we did not record a baseline percentage cover prior to passive warming treatments). A considerable gradient of moss growth rates has been observed from the sub-Antarctic islands to the Antarctic continent, with reports of relative vertical growth rates for Antarctic mosses ranging from 0Á2 to 32 mm year -1 (Convey et al, 2014). We saw no differences in height of P. alpinum gametophytes between the two treatments; however, the overall lateral moss cover coupled with a decrease in canopy density of P. alpinum suggest that Antarctic mosses may display plasticity in canopy density as a response to changing environmental factors.…”

“…A small percentage of the Antarctic continent is seasonally ice free (estimated 0Á34 %) (Convey et al, 2014), yet these areas represent unique terrestrial communities. Antarctica is colonized almost exclusively by the hardiest of microorganisms, plants, lichens, invertebrates and birds (Chown et al, 2015).…”

“…Smith, 1994;Day et al, 1999Day et al, , 2008Hill et al, 2011;Torres-Mellado et al, 2011), while fewer have examined moss communities (for reviews, see Robinson et al, 2003;Bramley-Alves et al, 2014). Continuing expansion of ice-free regions in Antarctica will increase the size of habitats suitable for colonization by stresstolerant mosses (Longton, 1988;Convey and Lewis Smith, 2006;Bramley-Alves et al, 2014;Convey et al, 2014); therefore, understanding the impacts of global warming on Antarctica's moss communities will be key to making informed predictions about the future of Antarctica's terrestrial ice-free margins (Smith, 1994;Royles et al, 2013).…”

Ecology and biogeochemistry of cyanobacteria in soils, permafrost, aquatic and cryptic polar habitats

“…The severe environmental conditions of continental Antarctica and high Arctic ([80°N) terrestrial habitats, which include freeze-thaw cycles, wide irradiance fluctuations (including Photosynthetically Active Radiation (PAR) and UV), and low nutrient supplies, results in generally depauperate habitats and very short seasons for biological growth Convey et al 2014;Cowan et al 2014). The variability in the environmental factors, together with the less than ideal levels of nutrients required for biological activity, severely restrict microbial communities in polar environments.…”

Survival of rapidly fluctuating natural low winter temperatures by High Arctic soil invertebrates

“…Environmental conditions in the terrestrial ecosystems of the polar regions are amongst the most extreme on the planet (Peck et al, 2006;Ávila-Jiménez et al, 2010;Convey, 2012;Convey et al, 2014). As a result, the stress tolerance adaptations of organisms within these ecosystems have formed a focus of research attention over many years.…”