GeloriniPhD (PDF , 6973kb) - University of York

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INTRODUCTION
analysis of fossil NPPs produces a unique palaeoecological archive, adjacent to pollen and other proxy indicators (such
as phytoliths, diatoms, dinoflagellates etc.) to provide insights into past environmental changes.
The majority of NPPs are the ascospores, conidia and chlamydospores of fungi, mainly derived from (i) pathogenic
fungi (Fusarium and Puccinia), (ii) mycorrhizal fungi (e.g., Glomus), and (iii) saprotrophic fungi (decomposers), of which
some may be coprophilous i.e. obligately growing on herbivore dung (e.g., Sordaria and Podospora). It is suggested that
most fungal spores deposited in and recovered from lake sediments, are fossilised at, or near, their source area where
sporulation occurred (van Geel, 2001; van Geel and Aptroot, 2006).
Coprophilous spores as anthropogenic indicators
In European palaeoecological studies (e.g., Willemsen et al., 1996; van Geel et al., 2003; Mazier et al., 2009), there is a long
tradition to link fossil spores of saprotrophic Ascomycota (= ascomycetes) to past livestock keeping, because these fungi
may be associated with the excrements of large herbivores, including soil contaminated with herbivore dung. However,
the term ‘coprophilous’ is not always properly used, making the relationship with wild and/or domestic herbivores more
ambiguous. In fact, most of the saprotrophic genera (e.g., Cercophora (as part of Lasiosphaeria), Coniochaeta, Apiosordaria
and Chaetomium) which are classified as ‘coprophilous’ have representatives that are hosted on other substrates such
as dead wood and plant debris (Hanlin, 1990; Romero et al., 1999; Asgari et al., 2007; Mukerji, 2010). Only a few genera
(e.g., Sordaria, Podospora, Delitschia and Sporormiella) inhabit dung obligately, i.e. exclusively (Ahmed and Cain, 1972;
Bell, 1983; Krug et al., 2004). Because of their association with different substrates, the ecological indicator value of most
saprotrophs is thus more complex and ambiguous than suggested by their (non-obligate) affinity with dung. Furthermore,
proper identification of these fungi, particularly when based on the spores only, is strongly impeded by the difficulty
of taxonomic discrimination. For instance, some saprotrophic fungi such as the obligate coprophilous genus Podospora
and the occasionally dung-inhabiting genera Cercophora, Schizothecium and Zopfiella produce morphologically similar
ascospores (Bell, 1983) and are grouped in a single morphotype, which weakens its dung indicator value. Therefore, it
is rather the abundance changes of obligate coprophilous spores (e.g., Sporormiella type) recorded in sediment records
which may indicate changes in population density of herbivores through time (Davis and Shafer, 2006).
Fig. vi. Life cycle of the coprophilous ascomycete Sordaria humicola (from Jennings and Lysek, 1996).