Sicily represents the Italian reservoir of chloroplast DNA diversity of Quercus ilex L. (Fagaceae)

Abstract

-Chloroplast DNA polymorphism was analysed in forty-four Italian holm oak populations. Results obtained with different markers (PCR-RFLP and SSR) were congruent, showing a clear geographic structure of genetic diversity and high value of genetic differentiation (G ST = 0.80). By combining PCR-RFLP and SSR, eight haplotypes were identified in Italy, six of them in Sicily. Most populations were fixed for one haplotype. Some populations from the extreme West Mediterranean (Morocco) and the extreme East Mediterranean areas (Crete) were interpreted as reproductively isolated populations because they had completely different haplotypes. These results strongly support the hypothesis of glacial refugia existing in southern Italy, and underline the high conservation value of natural tree populations in Sicily, in which most diversity was detected. Quercus ilex / PCR-RFLP / SSR / genetic differentiationRésumé -La Sicile, réservoir italien de la diversité de l'ADN chloroplastique de Quercus ilex L. Le polymorphisme de l'ADN chloroplastique a été analysé chez 44 populations italiennes de chêne vert. Les résultats obtenus avec différents marqueurs (PCR-RFLP et SSR) ont été cohérents, montrant clairement une structure géographique de la diversité génétique et une valeur élevée de la différentiation génétique (G ST = 0,80). En combinant PCR-RFLP et SSR, huit haplotypes ont été identifiés en Italie dont six en Sicile. La plupart des populations ont été fixées par un haplotype. Des populations de l'extrême ouest méditerranéen (Maroc) et de l'extrême est (Crète) ont été interprétées comme des reproductions de populations isolées parce qu'elles ont des haplotypes différents. Ces résultats supportent fortement l'hypothèse d'un refuge glaciaire existant dans le Sud de l'Italie et soulignent la grande importance de la conservation des populations d'arbres en Sicile dans lesquelles une grande diversité a été détectée. Quercus ilex / PCR-RFLP/SSR / différentiation génétique

Molecular phylogeny and genetic diversity of Tunisian Quercus species using chloroplast DNA CAPS markers

“…The presence of two chlorotypes of Q. ilex in Kessra (Siliana) can be explained by Two hypotheses: (i) these chlorotypes are different for each other and constituted two different taxonomic genera such as Quercus rotundifolia and Q. ilex species; (ii) One taxonomic genus diverged and gave these two different chlorotypes of Q. ilex which are represented by two infra-specific taxonomic ranks. The number of chlorotypes described in Tunisia is lower than that registered in Italy (Fineschi et al, 2005).…”

Narrow genetic base in forest restoration with holm oak (Quercus ilex L.) in Sicily

“…Ecosystem restoration is an issue of major concern to forest management in Sicily 280 and, regarding Quercus ilex genetic resources, priority has to be given to a 281 conservation forestry to preserve the specific genetic diversity found in Sicilian 282 populations [11,28,31]. Quite the contrary, the results of this study showed an 283 overall significant reduction of genetic diversity and a significant difference in 284 genetic composition of seedling lots in comparison with the natural seed origin stand.…”

Geography and host biogeography matter for understanding the phylogeography of a parasite

“…Although the presence of usual phylogeographic breaks does not exclude co-differentiation between Heligmosomoides and its host, co-differentiation might not be the most likely cause of these interruptions. In contrast, other phylogeographic breaks shared by Heligmosomoides and A. sylvaticus in South Western Europe do not correspond to phylogeographic breaks typically found in many other taxa: i.e., the differentiation of Sicily from continental Italy (even if few studies showed that Sicily is a hotspot of biodiversity in Europe (Randi et al, 2003;Fineschi et al, 2005;Fritz et al, 2005)), and the differentiation of Maghreb populations from Spain. These shared specific phylogeographic breaks are, in contrast to usual phylogeographic fractures, good clues arguing for long-term co-differentiation between the two species (Thompson, 2005).…”