Evidence for widespread endemism among Antarctic micro-organisms

Abstract

Understanding the enormous diversity of microbes, their multiple roles in the functioning of ecosystems, and their response to large-scale environmental and climatic changes, are at the forefront of the international research agenda. In Antarctica, where terrestrial and lacustrine environments are predominantly microbial realms, an active and growing community of microbial ecologists is probing this

Pole-to-Pole Connections: Similarities between Arctic and Antarctic Microbiomes and Their Vulnerability to Environmental Change

“…Even though temperate habitats from alpine areas in New Zealand and marine influenced sites in Europe are not fully comparable to polar habitats, these results are corroborated by studies on eukaryote biogeography finding bi-polar distributions of fungal OTUs (Cox et al, 2016), testate amoebae (Yang et al, 2010), and bryophyte species (Biersma et al, 2017). These findings suggest that the global dispersal of certain (microbial) species is combined with environmental selection shaping bacterial communities in the polar regions (Vyverman et al, 2010;Chong et al, 2015;Cox et al, 2016), though temporal (Rochera et al, 2010) or spatial (Villaescusa et al, 2013) variability in environmental conditions can cause differences among prokaryotic meta-communities in polar habitats. Highly seasonal conditions in the polar regions (Chong et al, 2015), such as the absence of light in winter (Alonso-Saez et al, 2012) freezing and limited freshwater availability Mohit et al, 2017) and low temperatures (Yergeau et al, 2007(Yergeau et al, , 2012Kleinteich et al, 2012) may cause the observed differences between polar and non-polar communities, since non-polar regions exhibit more moderate environmental conditions.…”

“…The percentage of these uniquely present OTUs was highest in non-polar samples in our dataset and likely reflects the higher similarity of the polar compared to non-polar regions. The somewhat larger fraction of endemic OTUs in the Antarctic compared to the Arctic may partially be explained by more extreme environmental conditions in Antarctica (Vyverman et al, 2010), but may also reflect the geographical situation of the two regions. The terrestrial Arctic has broad northsouth connections over continental land masses, ocean sectors and ecoclimatic zones, whereby wind, water currents and migrating animals may serve as vectors for species dispersal.…”

“…In contrast, the Antarctic continent is oceanographically as well as meteorologically isolated from the rest of the globe (Clarke et al, 2005;Barnes et al, 2006;Pointing et al, 2015). This geographic isolation has been speculated to cause a higher degree of genetic separation and thus be the driver for microbial endemism on the Antarctic continent (Vincent, 2000b;Vyverman et al, 2010;Hahn et al, 2015) as well as for Southern Ocean benthos (Griffiths et al, 2009). Isolated microhabitats in combination with local and regional distance-decay on the wide-ranging Antarctic continent may additionally provide ecological niches for a high microbial diversity and a high level of endemism (Yergeau et al, 2007;Vyverman et al, 2010).…”

“…This geographic isolation has been speculated to cause a higher degree of genetic separation and thus be the driver for microbial endemism on the Antarctic continent (Vincent, 2000b;Vyverman et al, 2010;Hahn et al, 2015) as well as for Southern Ocean benthos (Griffiths et al, 2009). Isolated microhabitats in combination with local and regional distance-decay on the wide-ranging Antarctic continent may additionally provide ecological niches for a high microbial diversity and a high level of endemism (Yergeau et al, 2007;Vyverman et al, 2010). The uniqueness of Antarctic habitats and the underrepresentation in public databases of OTUs found here in combination with the high percentage of potentially endemic microbial OTUs detected in the south polar region, highlights the importance of specially protected areas for the conservation of microbial diversity in the Antarctic (Hughes et al, 2015).…”

“…The polar regions therefore provide a unique opportunity to test biogeographic patterns of microbial diversity, providing predictors/indications of the future consequences of environmental change. The survival strategies and dispersal limitations, genetic identity and endemic character of polar microorganisms and, thus, their resilience and sensitivity are still under discussion (Vincent, 2000b;Taton et al, 2006;Jungblut et al, 2010;Vyverman et al, 2010). A comprehensive exploration of these microbial features using consistent methodology and sampling has been difficult to date due to the remoteness and inaccessibility of the polar regions.…”