Abstract
Although research on microbial biogeography has made great progress in the past decade, distributions of terrestrial microbial communities in extreme environments such as Antarctica are not well understood. In addition, knowledge of whether and how historical contingencies affect microbial distributions at small spatial scales is lacking. Here, we analyzed soil-borne microbial (bacterial, archaeal, and fungal) communities in 12 quadrat plots around the Fildes Region of King George Island, maritime Antarctica, and the communities were divided into two groups according to the soil elemental compositions and environmental attributes of Holocene raised beach and Tertiary volcanic stratigraphy. Prokaryotic communities of the two groups were well separated; the prokaryotic data were primarily correlated with soil elemental compositions and were secondly correlated with environmental attributes (e.g., soil pH, total organic carbon, NO3-, and vegetation coverage; Pearson test, r = 0.59 vs. 0.52, both P < 0.01). The relatively high abundance of P, S, Cl, and Br in Group 1 (Holocene raised beach site) was likely due to landform uplift. Lithophile-elements (Si, Al, Ca, Sr, Ti, V, and Fe) correlated with prokaryotic communities in Group 2 may have originated from weathering of Tertiary volcanic rock. No significant correlations were found between the fungal community distribution and both the soil elemental composition and environmental attributes in this study; however, Monte Carlo tests revealed that elements Sr and Ti, soil pH, sampling altitude, and moss and lichen species numbers had significant impacts on fungal communities. The elements and nutrients accumulated during the formation of different landforms influenced the development of soils, plant growth, and microbial communities, and this resulted in small-scale spatially heterogeneous biological distributions. These findings provide new evidence that geological evolutionary processes in the Fildes Region were crucial to its microbial community development, and the results highlight that microbial distribution patterns are the legacies of historical events at this small spatial scale. Based on this study, the ice-free regions in maritime Antarctica represent suitable research sites for studying the influence of geomorphological features on microbial distributions, and we envision the possibility of a site-specific landform assignment through the analysis of the soil prokaryotic community structure.
Highlights
Investigations of microbial communities at different spatial scales and the factors that affect their distributions are fundamental aspects of microbial biogeography (Martiny et al, 2006; Lozupone and Knight, 2007)
Pairwise correlative comparisons between elements demonstrated that P, S, Cl, and Br were positively correlated with each other, and they were negatively correlated with Mg, Al, Si, Ca, Mn, Zn, Sr, V, Fe, and Ti, which displayed positive correlations with each other (Supplementary Figure S1)
Significant differences were observed in the environmental attributes between Group 1 and Group 2 (PERMANOVA test, Pseudo-F = 15.17, P < 0.01), and these consisted of lower soil pH values and higher total organic carbon (TOC), NH4+, NO−3, and moisture contents in Group 1
Summary
Investigations of microbial communities at different spatial scales and the factors that affect their distributions are fundamental aspects of microbial biogeography (Martiny et al, 2006; Lozupone and Knight, 2007). In contrast to the increasing amount of research on other topics related to microbial distributions, knowledge about historical contingency effects is lacking (Fukami, 2015), and in particular, historical contingency effects on microbial community distributions at small spatial scales have not been elucidated thoroughly yet. This lack of knowledge may be due in part to the large spatial scales of influence of one historical event, i.e., there may be little variation over a small spatial region, and the tendency for legacy effects of a historical event to be overwhelmed by any effect from contemporary environmental factors at small spatial scales
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