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Within‐population genetic structure and clonal diversity of a threatened endemic metallophyte, Viola calaminaria (Violaceae)
Author(s) -
Bizoux JeanPhilippe,
Mahy Grégory
Publication year - 2007
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.94.5.887
Subject(s) - biology , biological dispersal , gene flow , genetic structure , population , violaceae , genetic diversity , ecology , seed dispersal , rapd , genetic variation , botany , genetics , gene , demography , sociology
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 = 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.