Vegetative reproduction and clonal diversity in Rhytidium rugosum (Rhytidiaceae, Bryopsida) inferred by morpho-anatomical and molecular analyses

Abstract

Many bryophytes exhibit specific life forms that result in the formation of distinct patches. This is primarily achieved by "consequent vegetative multiplication" through indeterminate growth and vegetative reproduction. Little, however, is known about the underlying mechanisms and genetic patterns. In this study on vegetative multiplication in bryophytes, we apply morpho-anatomical and molecular (AFLP fingerprinting) techniques to analyze the vegetative reproduction system, clonal diversity, and habitat colonization of a pleurocarpous moss, Rhytidium rugosum (Rhytidiaceae). Morpho-anatomically, three types of vegetative diaspores are identified and illustrated: ramets, separated after decay and disintegration of older shoot parts (clonal reproduction); brood branches/branchlets; and caducous shoot apices (both vegetative reproduction s.str.). The AFLP fingerprinting of 35 samples (from two plots in Thuringia, further German populations, and from France, Russia, and Canada) resulted in the identification of three clones from the two plots, each comprising two to 15 samples with identical fingerprints. Samples from one clone occurred in both plots, thus proving dispersal of vegetative diaspores. The AFLP analysis further revealed close relationships of the plot samples, which suggest a clonal rather than generative (sexual) origin of the population.

Genetic diversity of the relict moss Rhytidium rugosum (Hypnales) in Europe inferred from the ITS region (nrDNA)

“…It is already stated that long distance dispersal exsists in other mosses (Sabovljević et al 2005. Pfeiffer et al (2006) suggests tree clonal vegetative diaspors in Rhytidium rugosum and clonal rather than generative (sexual) origin of the genetically variable populations they studed. They also state the mixed genetically distinct populations in the same plot of small area of occupancy in Thuringia (E. Germany).…”

Phylogeography of Alpine populations of Rhytidium rugosum (Bryophyta) in a European context

“…For example, the OEL population is known to have passed through periods with much less available habitat around 6 and 1.5 kA BP (Hedenäs 2015;Königsson 1968). Regional distinctiveness could also be due to restriction to clonal reproduction (Pfeiffer et al 2006) and genetic drift due to low effective population sizes as was suggested for some Scandinavian Rhytidium populations (Hedenäs 2015). Because the southern Scandinavian populations immigrated from south of the LGM ice shield, their haplotype compositions, which differ from those in northern Scandinavia, most likely reflect that of the LGM population of the western European lowlands (Hedenäs 2015).…”

“…The species has separate male and female plants (dioicous) and sporophytes are nowadays rarely seen in Europe except in the Gudbrandsdalen area in southern Norway, where they are common and regularly produced (Hedenäs 2014(Hedenäs , 2015. The moss produces spores, which are 10.5-15.0 lm in diameter and can disperse far by wind, and vegetative fragments that vary from a few mm to a few cm (Pfeiffer et al 2006). The smaller such fragments can disperse relatively far in windy environments.…”

Glacial refugia and post-glacial colonization patterns in European bryophytes

“…Inbreeding depression is expected to be low in plants where selfing is the dominant mating system (Lande and Schemske 1985), as demonstrated in a study using a moss model system (Taylor et al 2007). Also, there are examples of bryophyte populations primarily established and maintained through vegetative diaspores (Pfeiffer et al 2006), implying that bryophyte populations may be stable and expanding despite low levels of sexual reproduction.…”