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Università degli studi della Tuscia - Viterbo (2015)

An integrated approach to the conservation of the threatened plant Malcolmia littorea (Brassicaceae)

De Vitis, Marcello

Titre : An integrated approach to the conservation of the threatened plant Malcolmia littorea (Brassicaceae)

Un approccio integrato per la conservazione di Malcolmia littorea (Brassicaceae), pianta minacciata di estinzione

Auteur : De Vitis, Marcello

Université de soutenance : Università degli studi della Tuscia - Viterbo

Grade : Dottorato di ricerca in Ecologia e gestione delle risorse biologiche 2015

Résumé
Malcolmia littorea (L.) R. Br. is a plant species occurring on sandy coastal habitats of South-West Europe (Portugal, Spain, France and Italy) and North-West Africa (Algeria and Morocco), which is characterised by a disjointed distribution. The continuous fragmentation and degradation of its natural habitat, mainly due to the anthropogenic impact, are threatening the persistence of this species in several regions of its distribution reducing the populations abundance. This PhD project had the aim of investigating several biological and ecological aspects of the study species in order to provide useful information for its efficient conservation. In 2013, a set of European populations was sampled for leaves and seeds. The leaves were used to conduct a population genetic study, in which five chloroplast and four nuclear microsatellite loci were analysed. The populations genetic structure was investigated and several genetic parameters were estimated and compared. The seeds were used to investigate the germination ability of the species across Europe. They were incubated at eight constant temperatures (0- 27°C) and then seed traits and germination data were compared among populations and tested for correlation with independent variables like the area occupied by the populations, latitude and climatic parameters. Furthermore, several in situ trials were conducted in order to study the ability of the species to form a soil seed bank and to understand the best method to reintroduce the species. From the genetic analysis, it was not detected any significant difference among populations in the within-population genetic diversity, even if they showed significant (P < 0.05) differentiation both for chloroplast and nuclear genome, forming three main genetic clusters. However, a high migration rate underlined the absence of a strong genetic structure across Europe. Based on the allelic composition and richness, three populations were identified as the priority conservation spots. The study on seed ecology confirmed the importance of both the genotypic and phenotypic components in regulating the pattern and the seasonality of seed germination, but also revealed that the population size can affect the germination ability. The smallest populations were found to show the lowest germination percentages. The results of the in situ trials were useful to understand the regeneration requirements of the species and evidenced the important tendency of the species in forming a soil seed bank. Concerning the species reintroduction, direct sowing method is preferred than transplanting but requires many seeds and so it is limited by the seed production of the native populations, while transplanting is always followed by a high transplants mortality and the cultivation method has to be improved.

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Page publiée le 21 novembre 2018