The aim of this study was to assess the genetic variation and population structure of the geophyte Leucojum aestivum L.
across the Po river valley (N-Italy), to inform conservation management actions with the selection of most suitable source
populations for translocation purposes. L. aestivum is self-incompatible and occurs in S-Europe in fragmented wetlands
and lowland forests along rivers. The species is particularly interesting for habitat restoration practices for its simplicity
of ex situ conservation and cultivation. AFLP analyses were carried out on 16 fragmented populations, using four primer
combinations. Correlations between genetic variation and demographic and ecological traits were tested. AFLP produced
a total of 202 bands, 95.5% of which were polymorphic. Our results suggest that L. aestivum holds low to moderate levels
of genetic diversity (mean Nei’s genetic diversity: H = 0.125), mostly within-population. We found a gradient of two main
biogeographic groups along western and eastern populations, while the STRU CTU RE analysis found that the most likely
number of clusters was K = 3, shaping a partially consistent pattern. We explain the unusual negative correlation between
genetic variation and population size with the high rate of vegetative reproduction. The levels of population differentiation
suggest that fragmentation in L. aestivum populations has occurred, but that an active gene flow between fragmented populations
still exists, maintained by flooding events or pollinators. Conservation management actions should improve habitat
connectivity, especially for pollinators that vehicle upstream gene flow. Moreover, the west–east structure due to the lithological
composition of the gravel and sand forming the alluvial plain of the Po river, should be considered when selecting
source populations for translocation purposes.
