RESUMEN
Genetic diversity and structure are described in the aquatic moss Platyhypnidium riparioides to assess its dispersal ability at a regional scale and to determine whether patterns of genetic differentiation correlate with environmental variation. Variation at six nuclear microsatellite loci from 50 populations in southern Belgium was investigated through Mantel tests, partial Mantel tests and spatial analysis of molecular variance. Overall patterns of genotypic variation showed strong differentiation among populations at a regional scale (F(ST) = 0.57). The high values of F(IS) observed within populations at both the ramet and genet levels, and the higher proportion of ramets with the same genotype than expected by chance, all point to a strongly clonal or selfing mating system. A genetic discontinuity was identified between northern and southern groups of populations. Within each group, F(ST) and geographical distances were significantly correlated. Partial Mantel tests suggest that genetic and ecological distances are significantly correlated in the southern group. The results point to strong dispersal limitation at the landscape scale and suggest that the southern and northern groups experienced different histories. Within the former, the correlation between genetic and ecological variation is suggestive of reproductive isolation among ecotypes.
Asunto(s)
Briófitas/genética , Fenómenos Ecológicos y Ambientales , Variación Genética , Agua , Alelos , Bélgica , Frecuencia de los Genes/genética , Geografía , Heterocigoto , Repeticiones de Microsatélite/genética , Ploidias , Dinámica Poblacional , Análisis de Componente Principal , Tamaño de la MuestraRESUMEN
Eight microsatellite loci from the aquatic moss Platyhypnidium riparioides were identified using the method of microsatellite-enriched libraries. Polymorphism was assessed in a sample of four populations of 20 individuals each from four streams of the Meuse hydrographic basin in southern Belgium. The markers amplified three to seven alleles per locus. Comparison of observed and expected heterozygosities as well as F-statistics (F(ST) = 0.62) reveals a significant genetic differentiation among populations. These markers will be useful for further investigation of population genetic structure and diversity at different nested spatial scales.