Browsing by Author "Valverde, Angel"

Now showing 1 - 3 of 3
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    Biodiversity: so much more than legs and leaves
    (AOSIS OpenJournals, 2013) Cowan, Donald A.; Rybicki, Edward P.; Tuffin, Marla; Valverde, Angel; Wingfield, Michael
    Microorganisms inhabit virtually every possible niche on Earth, including those at the outer envelope of survival. However, the focus of most conservation authorities and ecologists is the ‘legs and leaves’ side of biology – the ‘macrobiology’ that can be seen with the naked eye. There is little apparent concern for the preservation of microbial diversity, or of unique microbial habitats. Here we show examples of the astounding microbial diversity supported by South Africa’s ecosystems and argue that because microbes constitute the vast majority of our planet’s species they should be considered seriously in the future protection of our genetic resources.
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    Hypolithic and soil microbial community assembly along an aridity gradient in the Namib Desert
    (Springer, 2013) Stomeo, Francesca; Valverde, Angel; Pointing, Stephen B.; McKay, Christopher P.; Warren-Rhodes, Kimberley A.; Tuffin, Marla I.; Seely, Mary; Cowan, Donald A.
    The Namib Dessert is considered the oldest desert in the world and hyperarid for the last 5 million years. However, the environmental buffering provided by quartz and other translucent rocks supports extensive hypolithic microbial communities. In this study, open soil and hypolithic microbial communities have been investigated along an East–West transect characterized by an inverse fog-rainfall gradient. Multivariate analysis showed that structurally different microbial communities occur in soil and in hypolithic zones. Using variation partitioning, we found that hypolithic communities exhibited a fog-related distribution as indicated by the significant East– West clustering. Sodium content was also an important environmental factor affecting the composition of both soil and hypolithic microbial communities. Finally, although null models for patterns in microbial communities were not supported by experimental data, the amount of unexplained variation (68–97 %) suggests that stochastic processes also play a role in the assembly of such communities in the Namib Desert.
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    Micro-Eukaryotic diversity in Hypolithons from Miers Valley, Antarctica
    (Multidisciplinary Digital Publishing Institute (MDPI), 2013) Gokul, Jarishma K.; Valverde, Angel; Tuffin, Marla; Cary, Stephen Craig; Cowan, Donald A.
    The discovery of extensive and complex hypolithic communities in both cold and hot deserts has raised many questions regarding their ecology, biodiversity and relevance in terms of regional productivity. However, most hypolithic research has focused on the bacterial elements of the community. This study represents the first investigation of micro-eukaryotic communities in all three hypolith types. Here we show that Antarctic hypoliths support extensive populations of novel uncharacterized bryophyta, fungi and protists and suggest that well known producer-decomposer-predator interactions may create the necessary conditions for hypolithic productivity in Antarctic deserts.