Biodiversità, filogenesi ed evoluzione dei funghi neri delle rocce
Author(s)
Isola, Daniela
Date Issued
February 18, 2010
Type
Doctoral Thesis
Abstract
Adaptation to different environments promotes differentiation of life and enhance biodiversity.
Under this perspective, extremophilic organisms, coping with high environmental pressure the main
factor for the adaptive radiation, are good candidates to study evolutionary mechanisms.
Rock surfaces are unique terrestrial habitats in which rapid changes in the intensity of radiation,
temperature, water supply and nutrient availability challenge the survival of microbes. A
specialised, but diverse group of free-living, melanised fungi are amongst the persistent settlers of bare rocks. First discovered in the hot deserts and in Antarctica, these fungi were shown to persistently colonise rock surfaces even in more temperate climates. These rock-inhabitants are particularly common in semiarid and arid habitats, where they may thrive both because of their extraordinary extremotolerance and absence of competitors. A number of specific and universally
present morphological and physiological characters enable them to tolerate surprisingly wide ranges of temperature, irradiation and osmotic stress. Their remarkable survival abilities along with a capacity to penetrate minerals make this guild attractive for investigations in microbial
ecophysiology and applied researches, such as biodeterioration of monuments and exobiology.
Moreover rock black fungi are a model to study evolution under extreme condition because they are
strongly selected by extreme variations in environmental factors.
Different studies were performed on black fungi about their phylogeny, to test their extraordinary
ability to tolerate chemical and physical conditions and many new taxa, some of them probably endemic, have been described. Nevertheless much more remains to be understood about their evolution and development of biochemical patterns in relation to adaptation to extreme environments.
For this reason the aim of this work was to deepen our knowledge about biodiversity and evolution of rock black meristematic fungi basing on phylogenetic approach; furthermore, the proteome analysis has been used to have insights on the way their genome has evolved and what has made them so special.
Results obtained allowed us to describe and publish two new genera, (Recurvomyces Selbmann &
de Hoog, gen. nov. (MycoBank MB511293) and Elasticomyces Zucconi & Selbmann, gen. nov.
(MycoBank MB511296)) and two new species (Recurvomyces mirabilis Selbmann & de Hoog, sp.
nov. (MycoBank MB51129) and Elasticomyces elasticus Zucconi & Selbmann, sp. nov.
(MycoBank MB511297); the description of further new taxa is in progress.
We have also have got evidences about clonal reproduction in a wide, diversified and
phylogenetically well defined group; this finding open new insights for evolution under extreme
conditions. Basing on the large sampling, we can confirm the possibility of endemism at generic
level for the previously described Antarctic genus Friedmanniomyces Onofri. Cryomyces Selbmann
et al., can be surmised to be endemic at species level (C. antarcticus Selbmann et al., and C. minteri Selbmann et al.) after the isolation of not yet described new species from Alps.
Additional information
Dottorato di ricerca in Evoluzione biologica e biochimica
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