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Conservatoire botanique national des Pyrénées et de Midi-Pyrénées

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Spatial genetic structure and clonal diversity of Anemone nemorosa in late successional deciduous woodlands of Central Europe / Ivana Stehlik in Journal of ecology, 88 (3) (2000) 

Public Citation [article]  inJournal of ecology > 88 (3) (2000) . - 424-435 Titre : Spatial genetic structure and clonal diversity of Anemone nemorosa in late successional deciduous woodlands of Central Europe Type de document : Imprimé Auteurs : Ivana Stehlik (1971-) ; Rolf Holderegger (1965-) Année de publication : 2000 Article en page(s) : 424-435 Langues : Anglais (eng) Mots-clés : Anemone sp. Note de contenu : 1 We tested whether established populations in similar environmental conditions exhibit similar or varying spatial genetic structures by comparing populations of the long-lived species Anemone nemorosa from a number of late successional deciduous woodlands in Central Europe. We discuss the ways in which genetic structure may have been shaped by clonal growth and sexual reproduction. 2 A standardized sampling strategy was used to collect 30 ramets from each of 20 populations. Genotypes of the samples were determined by allozyme electrophoresis and analysed assuming that A. nemorosa shows tetraploid-tetrasomic inheritance. 3 Genetic variation and clonal diversity were high compared with other clonal species. Most (95%) of the sampled ramets had unique multilocus genotypes with only 22 examples occurring more than once. Differences between observed and expected heterozygosities within populations were generally small to moderate. Fixation indices (mean of over 14 loci) in the populations ranged between 0.08 and 0.56 (grand mean = 0.21) confirming reports that the breeding system in A. nemorosa is predominantly outcrossing or mixed-mating. 4 Limited historic gene flow among populations (Nm = 0.62) was reflected by high population differentiation (GST = 0.29), low genetic identities among populations and a non-significant correlation between these identities and geographical distances. 5 Spatial autocorrelation (Moran’s I) showed no significant differences in genetic structures between populations under similar environmental conditions. Samples taken less than 0.5 m apart were genetically more closely related than to more distant samples, but similarity of genotypes decreased only slightly with further increase in distance. 6 The high levels of genetic variation found in populations of A. nemorosa are probably due to repeated seedling recruitment and the outcrossing or mixed-mating breeding system, whereas vegetative propagation and short-distance seed dispersal may contribute to the positive genetic autocorrelation observed at a small spatial scale. Identifiant : DOI : 10.1046/j.1365-2745.2000.00458.x Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=137830 Stehlik, I., Holderegger, R., 2000 . Spatial genetic structure and clonal diversity of Anemone nemorosa in late successional deciduous woodlands of Central Europe. Journal of ecology, 88(3): 424-435.

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Article (2000) URL

Positive and negative interactions at different life stages of a colonizing species (Quercus humilis) / Olivier Rousset in Journal of ecology, 88 (3) (2000) 

Public Citation [article]  inJournal of ecology > 88 (3) (2000) . - 401-412 Titre : Positive and negative interactions at different life stages of a colonizing species (Quercus humilis) Type de document : Numérique Auteurs : Olivier Rousset (1965-) ; Jacques Lepart (1947-) Année de publication : 2000 Article en page(s) : 401-412 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Climax, succession plantes, dynamique végétation [CBNPMP-Thématique] Interactions interspécifiques Mots-clés : Quercus humilis Miller  Buxus sempervirens L.  Juniperus communis L. Résumé : 1 The downy oak Quercus humilis has recently recolonized the Causse du Larzac plateau in southern France. We studied the influence of the shrubs Buxus sempervirens and Juniperus communis on Q. humilis establishment, and of Buxus on the growth of established Q. humilis individuals. 2 Percentage germination of experimentally planted Q. humilis was higher under shrubs than in nearby open areas and higher on the north than the south side of the canopy. Germination where part of the canopy has been removed was similar to that away from the shrubs, suggesting that the facilitation mechanism is related to changes in microclimate rather than to a soil effect. 3 When exposed to sheep for 1 month, 100% of 326 unprotected oak seedlings were grazed, causing 44% mortality. The presence of Buxus and Juniperus improved seedling survival by protecting them against sheep grazing and summer drought. Predation by rodents was however greater under shrub cover. 4 The highest leaf dry mass of oak seedlings was recorded under Juniperus where light conditions seem more favourable for growth than under Buxus (direct effect) or in grassland (indirect effect). The growth of naturally established individuals of Q. humilis (in terms of total leaf mass per annual branch and width of rings) was lower under Buxus than in grassland but the values became similar once the canopy was overtopped. 5 The balance between positive and negative interactions varied in relation to the life stage of Q. humilis and the two shrub species. Regeneration of Q. humilis in open grassland was prevented by grazing. The protection offered by shrubs continues to offset the negative interference on growth, particularly under Buxus, so that plants could survive to overtop the shrub canopy and reach maturity. The succession pathway therefore depends closely on the distribution of shrubs in the grassland. Identifiant : DOI : 10.1046/j.1365-2745.2000.00457.x Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=156368 Rousset, O., Lepart, J., 2000 . Positive and negative interactions at different life stages of a colonizing species (Quercus humilis). Journal of ecology, 88(3): 401-412.

Documents numériques

Article (2000) URL