Genetic variation in the clonal bryophyte Hylocomium splendens at hierarchical geographical scales in Scandinavia

Abstract

The widespread bryophyte Hylocomium splendens was sampled in a hierarchical fashion from populations representing four Scandinavian vegetation zones. Allozyme electrophoresis revealed variation at 11 out of 13 screened loci, allowing accurate identification of genotypes. From a total sample of 298 shoots 79 genotypes could be detected, giving the proportion of distinguishable genotypes (PD) of 0.265. The total allelic diversity (HT) based on polymorphic loci was 0.274. The relative differentiation among populations was low (GST= 0.073), indicating a high level of gene flow. Differences in population structuring occurred between a subarcticalpine site vs. three lowland sites. The subarctic-alpine population had one widespread clone, which appeared to be propagated by dispersal of vegetative fragments. That population also comprised many rare genotypes, often occurring together within 10 x 10 cm patches. The lowland populations had genotypes that were locally common and often dominant within the patches. When identical genotypes were observed in multiple patches within these populations, it was usually statistically highly probable that they had arisen by independent sexual recombinations.

Genetic variation in the moss Homalothecium lutescens in relation to habitat age and structure

“…Mitt. Zielinski and Wachowiak-Zielinska 1995;Cronberg et al 1997;Cronberg 2002), while the overall A at polymorphic loci was moderate (2.04, compared with a range of 1.8 to 4.10).…”

“…A similar relationship was found in a study of the grass B. media in fragmented calcareous grasslands, where genetic variation was best described by the present-day pattern of grassland connectivity rather than by historical landscape patterns (Helm et al 2009). (Wyatt et al 1989;Cronberg et al 1997Cronberg et al , 2005. The low but significant between-deme genetic differentiation (in terms of G ST and Jost's D), and the lack of a significant association between genetic and geographic distances, is in agreement with the fact that the grasslands containing the demes were all more or less connected with each other about 180 years ago, suggesting that the demes shared a common gene pool.…”

“…The heterozygous condition was treated as a separate "allele" at these loci. A heterozygous banding pattern recorded for IDH in Hylocomium splendens has previously been interpreted as representing a duplication of one of the IDH loci (Cronberg et al 1997).…”

“…Electrophoretic procedures followed the methods in Cronberg et al (1997) with minor modifications. Three buffers systems were used: (i) a histidine buffer (Soltis et al 1983 (Soltis et al 1983; No.…”

“…The computer program Fstat (Goudet 2001) was used to calculate gene diversity (H S , unbiased estimate; Nei 1987) and mean number of alleles per locus (A, unbiased estimate; El Mousadik and Petit 1996). H S was calculated for two levels of organization: (1) ramet level (H S R), considering each shoot as a separate entity, and (2) genet level (H S G), considering each haplotype in a deme as a separate entity and assuming that, within a deme, individual shoots with identical allozyme markers belong to the same clone (Cronberg et al 1997). To eliminate errors caused by the sampling not being fully randomized (the shoots were gathered in pairs), the data set was split into two parts when calculating H S R and H S G (the split being between the two shoots in each sampled pair).…”