Abstract
Aquatic hyphomycetes occur worldwide on a wide range of plant substrates decomposing in freshwaters, and are known to play a key role in organic matter turnover. The presumed worldwide distribution of many aquatic hyphomycete species has been based on morphology-based taxonomy and identification, which may overlook cryptic species, and mask global-scale biogeographical patterns. This might be circumvented by using DNA sequence data. The internal transcribed spacer (ITS) region from rDNA was recently designated as the most suitable barcode for fungal identification. In this study, we generated ITS barcodes of 130 isolates belonging to 6 aquatic hyphomycete species (Anguillospora filiformis, Flagellospora penicillioides, Geniculospora grandis, Lunulospora curvula, Tetrachaetum elegans and Tricladium chaetocladium), and collected from streams of Southwest Europe (86 isolates) and East Australia (44 isolates). European and Australian populations of 4 species (A. filiformis, F. penicillioides, G. grandis and T. elegans) grouped into different clades, and molecular diversity indices supported significant differentiation. Continents did not share haplotypes, except for T. chaetocladium. Overall results show substantial population diversity for all tested species and suggests that the biogeography of aquatic hyphomycetes may be species-specific.
Highlights
Most large eukaryotic plants and animal species have relatively narrow geographic distributions
Dataset The dataset consists of 130 internal transcribed spacer (ITS) sequences belonging to 6 aquatic hyphomycete species, A. filiformis, F. penicillioides, G. grandis, L. curvula, T. elegans and T. chaetocladium, sampled from streams of Europe (86 isolates) and Australia (44 isolates) between 2009 and 2011 and separated by ca. 18000 km
Isolates of T. elegans showed the highest variation in sequence length, while those of G. grandis (519 bp) and T. chaetocladium did not vary
Summary
Most large eukaryotic plants and animal species have relatively narrow geographic distributions. Fenchel and Finlay [2] and Finlay and Fenchel [3] extended the assumption of global distribution to eukaryotic microorganisms. They postulated a transition from ubiquity to biogeography at a body size between 1 and 10 mm. Molecular genetic evidence has shown that reliance on morphological data inflates the range of geographical distribution of many microorganisms, including prokaryotes, diatoms and protists [4]. Strains of Neurospora discreta were resolved into several distinct phylogenetic species with different geographic distributions [6,7]. Even though the single morphospecies was split into two phylospecies, both exhibited global distribution [10]
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