Specialist plant species harbour higher reproductive performances in recently restored calcareous grasslands than in reference habitats

peer reviewedBackground and aims_Calcareous grasslands are local biodiversity hotspots in temperate regions that suffered intensive fragmentation. Ecological restoration projects took place all over Europe. Their success has traditionally been assessed using a plant community approach. However, population ecology can also be useful to assess restoration success and to understand underlying mechanisms. Methods_We took advantage of three calcareous grassland sites in Southern Belgium, where reference parcels coexist with parcels restored in the late twentieth century and with more recently restored parcels. We evaluated the colonization stage of three specialist species (Sanguisorba minor, Potentilla neumanniana and Hippocrepis comosa) using occurrence data. We also measured the reproductive traits of 120 individuals per species and compared components of fitness between recent restorations, old restorations and reference habitats. Key results_We found that the occurrence of H. comosa was similar in the different restoration classes, whereas both P. neumanniana and S. minor occurrences decreased from reference grasslands to recent restorations. In contrast, these two latter species exhibited a much higher reproductive output in recent restorations, thanks to an increased production of flowers and seeds. Conclusions_Our results suggest that, during colonization of recently restored calcareous grasslands, favourable environmental conditions, low competition and sufficient genetic mixing may lead to an increased fitness of individuals and a faster population growth than in the reference habitat. These results demonstrate how population processes can increase ecological resilience and highlight the interest of a population-based approach to assess the success of ecological restoration

Genetic Diversity of Andean Tuber Crop Species in the in situ Microcenter of Huanuco, Peru

peer reviewedAndean tuber crop species oca (Oxalis tuberosa Molina), ulluco (Ullucus tuberosus Caldas), and mashua (Tropaeolum tuberosum Ruiz & Pav.) play major roles in Andean communities. These species show high variability but are threatened with genetic erosion. To study the management of genetic resources of neglected vegetatively propagated crop species, we studied genetic diversity and structure of these species in an in situ diversity microcenter (Huanuco, Peru). A sample of 15 varieties of oca, 15 of ulluco, and 26 of mashua was analyzed with the inter simple sequence repeats (ISSR) molecular markers. Mean genetic distances and global genetic diversities were high for the three species, with higher values for mashua than for oca and ulluco. Assignment technique divided both oca and ulluco samples into two genetic clusters; the mashua sample probably belongs to a single genetic cluster. Inter simple sequence repeats (ISSR) technique showed intravarietal genetic variability for most varieties, suggesting an underestimation of the in situ genetic variability. These results are discussed considering how variation in breeding systems and farmers' practice influenced patterns of genetic diversity. Our findings confirm the hypothesis of a considerable amount of variability found in neglected Andean tubers and are essential to deserve adequate conservation strategies and to maintain genetic resources of neglected Andean tuber crop species under a threat of genetic erosion

Strong spatial genetic structure in five tropical Piper species: should the Baker–Fedorov hypothesis be revived for tropical shrubs?

Fifty years ago, Baker and Fedorov proposed that the high species diversity of tropical forests could arise from the combined effects of inbreeding and genetic drift leading to population differentiation and eventually to sympatric speciation. Decades of research, however have failed to support the Baker–Fedorov hypothesis (BFH), and it has now been discarded in favor of a paradigm where most trees are self-incompatible or strongly outcrossing, and where long-distance pollen dispersal prevents population drift. Here, we propose that several hyper-diverse genera of tropical herbs and shrubs, including Piper (>1,000 species), may provide an exception. Species in this genus often have aggregated, high-density populations with self-compatible breeding systems; characteristics which the BFH would predict lead to high local genetic differentiation. We test this prediction for five Piper species on Barro Colorado Island, Panama, using Amplified Fragment Length Polymorphism (AFLP) markers. All species showed strong genetic structure at both fine- and large-spatial scales. Over short distances (200–750 m) populations showed significant genetic differentiation (Fst 0.11–0.46, P < 0.05), with values of spatial genetic structure that exceed those reported for other tropical tree species (Sp = 0.03–0.136). This genetic structure probably results from the combined effects of limited seed and pollen dispersal, clonal spread, and selfing. These processes are likely to have facilitated the diversification of populations in response to local natural selection or genetic drift and may explain the remarkable diversity of this rich genus

Within-Population Genetic Structure And Clonal Diversity Of A Threatened Endemic Metallophyte, Viola Calaminaria (Violaceae)

We studied the within-population genetic structure and the clonality extent of Viola calaminaria, a rare endemic species of calamine soils, by means of RAPD markers in two populations (one recent and one ancient) with expected harsh and heterogeneous heavy-metal stress. At a very local scale (0.2 3 m), clonal propagation was detected in both populations, but the levels of clonal diversity were high (number of genets/number of ramets sampled ¼ 0.9 [recent] and 0.76 [ancient]) and the maximal observed extension of the clones was 0.4 m. This indicated that clonality is not, for the species, an important mode of propagation and that clonal growth cannot be interpreted as a strategy for propagating or perpetuating adapted genotypes under harsh ecological constraints. Spatial autocorrelations revealed a significant (P , 0.001) negative value of correlogram slope in the two populations even when a single individual per clone was considered (i.e., analysis at the genet level). We conclude that spatial genetic structure at a very local scale reflects limited gene flow due to restricted seed dispersal rather than variation in clonal pattern in response to environmental heterogeneity. At a larger scale (2–30 m), spatial autocorrelations revealed a positive (P , < 0.001) correlation at , 3 m and a random pattern at larger distances for the two populations. This suggested a patchy distribution of the genetically linked individuals associated with a disrupted pattern at a longer distance probably due to gene flow by pollen dispersal and a seed bank effect. The implications for the conservation of V. calaminaria are discussed