Bryophytes generally have broad geographic ranges that suggest high dispersal ability. The aim of this study was to test hypotheses about dispersal limitation, as indicated by isolation by distance (IBD), in four spore producing species of the moss genus Sphagnum (S. carolinianum, S. missouricum, S. macrophyllum, S. pylaesii), and to assess whether plants in the southern United States harbor high levels of unique alleles and/or other indicators of exceptional genetic diversity. IBD was detected in all four species, but regional patterns of genetic structure were very species-specific. One species, S. macrophyllum, exhibited differentiation between northern and southern genetic groups that appear to reflect more ancient phylogenetic diversification.

DNA samples were obtained from 203 collections of Sphagnum missouricum, 61 of S. carolinianum, 223 of S. macrophyllum and 110 of S. pylaesii. Microsatellite genotyping varied somewhat among species because the study was conducted over a number of years. Samples of S. missouricum and S. carolinianum were scored for 12 loci (1, 9, 10, 12, 14, 17, 18, 19, 20, 22, 26, 28) numbered as in Shaw et al. (2008). For S. macrophyllum, 165 samples were scored for 16 loci (1, 4, 5a, 5b, 7, 9, 10, 12, 14, 17, 18, 19, 20, 29, 30). For S. pylaesii, 110 samples were scored for 17 loci (1, 4, 5, 6, 6a, 7, 9, 10, 12, 14, 17, 18, 19, 20, 22, 28, and 29. Details of PCR conditions, multiplexing, and fragment-size scoring followed Shaw et al. (2008).

Files labeled as "-noclones" have had samples from a location that have identical or indistinguishable genotypes removed. 

Files are in STRUCTURE format, one line per sample.

S. pylaesii and S. macrophyllum are from haploid gametophytes (one allele per locus). S. carolinianum and S. missouricum are from diploid gametophytes (2 alleles per locus).

Missing data are coded as 0 or -9.