DOI: 10.5061/dryad.b8gtht7g5
title: Molecular and quantitative genetic variation within and between populations of the declining grassland species Saxifraga granulata

description: Formerly common plant species are expected to be particularly susceptible
 to recent habitat fragmentation. We studied the population genetics of 19
 recently fragmented Saxifraga granulata populations (max. distance 61 km)
 in Luxembourg and neighbouring Germany using RAPD markers and a common
 garden experiment. We assessed (1) the relationships between plant
 fitness, quantitative genetic variation, molecular genetic variation and
 population size, and (2) the relative importance of genetic drift and
 selection in shaping genetic variation. Molecular genetic diversity was
 high but did not correlate with population size, habitat conditions or
 with plant performance. Genetic differentiation was low (FST = 0.079 ±
 0.135) and there was no isolation by distance. Longevity, clonality and
 the long-lived seed bank of S. granulata may have prevented strong genetic
 erosion and genetic differentiation among populations. However, genetic
 distinctness increased with decreasing genetic diversity indicating that
 random genetic drift occurred in the studied populations. Quantitative and
 molecular genetic variation were correlated and their differentiation (QST
 vs. FST) among S. granulata populations was similar, suggesting that
 mainly random processes have shaped the quantitative genetic
 differentiation among populations. However, pairwise quantitative genetic
 distances increased with geographic and climatic distances, even when
 adjusted for molecular genetic distances, indicating diversifying
 selection. Our results indicate that long-lived clonal species may be
 buffered at least temporarily against the negative effects of
 fragmentation. The relationship between quantitative genetic and
 geographic distance may be a more sensitive indicator of selection than
 QST - FST differences.
description: In 2003, we selected 15 plants
 along a 15 m transect in each of 19 populations in Luxembourg and in the
 neighbouring state of Rheinland-Pfalz in Germany for a study on the
 genetic structure of the populations. We counted the number of flowers in
 the field, took leaf
 samples for a RAPD molecular genetic analysis and collected seeds for the
 cultivation of plants in a common garden and the subsequent measurement of
 quantitative traits. This dataset includes individual genotype data
 based on the presence or absence of reliable bands of RAPD amplification
 products at 52 polymorphic band positions for 247
 <em>Saxifraga</em> <em>granulata</em> samples
 collected in 19 populations, the measurements of quantitative traits on F1
 plants cultivated in a common garden from seeds collected in 19
 populations, data on
 quantitative genetic, molecular genetic, geographic and climatic variables
 of the populations as well as the pairwise climatic, geographic, quantitative
 genetic and molecular genetic distances between the 19 populations. Data
 are stored in separate files which relate to each other via the key
 variable Popno (the number of a population).
description: Excel or other tabular software, notepad