Dermatocarpon luridum is a subaquatic lichen which is distributed within temperate climatic zones around the world. It colonizes rock substrata along the shoreline of lakes and rivers of watersheds that regularly experience water level fluctuations. The mycobiont produces perithecia with small, simple spores that are thought to be wind dispersed. The photobiont, Diplosphaera chodatii, occurs both free-living and lichenized but little is known about its distribution and dispersal. The goal of this study was to compare the population structure of the photobiont from lakes and rivers in central North America with those of Europe. Specimens were collected in Manitoba, Canada and Austria. Population structure of the algal symbiont was assessed using the internal transcribed spacer (ITS) of ribosomal DNA (rDNA) and actin gene sequences. Results showed that genetic diversity and gene flow was high within local populations, but gene flow was low between continental populations. Low levels of gene flow between the most distant populations support the isolation-by-distance theory. The photobiont on both continents is also reported to be the photobiont for other lichen species contributing to photobiont availability for D. luridum.
Six halophytic plants including Atriplex patula, Glaux maritima, Hordeum jubatum, Puccinellia nuttalliana, Salicornia rubra, and Suaeda depressa were collected at various growth stages throughout the growing season of the summers 1982 and 1983 from an inland salt marsh at Delta, Man. Washed root and shoot pieces of each plant species were plated on culture medium, incubated, and surveyed for cauloplane and rhizoplane fungi. A total of 31 taxa were isolated including 3 asco-mycetes, 2 coelomycetes, 1 zygomycete, and 25 hyphomycetes. Morphological features, plant type, cultures, and taxonomic deposition are presented for each fungal taxon.
Seeds of the H. murinum aggregate were collected from much of the range of the group and soluble protein extracts were subject to gel-electrophoresis analysis. Diploid, tetraploid and hexaploid plants were readily differentiated. Analysis using a similarity matrix and dendrogram revealed further groups within the ploidy levels and indicated inter-group relationships. Evidence obtained supported karyological results, suggesting that tetraploid and hexaploid plants are allopolyploids, and that one of their putative parents is a diploid known from Turkey and adventive in Australia. Within the tetraploids there is little correspondence between groups detected by either gel-electrophoresis or karyology, and the species H. lepovinum (mostly southern) and H. murinum (mostly northern).
Morphological data has been assembled from a large collection of fruiting heads of the Hordeum murinum aggregate. Computer analysis reveals two major taxa, which, using seven characters, can be readily separated. These are recognized as H. murinum L. and H. leporinum Link. The former is primarily north‐western and the latter south‐eastern in distribution. Both plants can occur sympatrically, and there is no evidence of a cline.
Diploid plants from south‐east Europe represent extreme H. leporinum types and these are recognized as a subspecies (H. leporinum Link ssp. glaucum (Steudel) Booth & Richards) stat. et comb. nov. Hexaploid plants of H. leporinum cannot be morphologically differentiated.
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