Abstract

Combining coalescence modelling, neutrality tests and environmental correlations,demographic history and non-neutral patterns of evolution in candidate genes relatedto drought stress and secondary compounds were investigated in two closely-relatedMediterranean conifers, Pinus pinaster Ait. and Pinus halepensis Mill. Amplicons coveringcandidate genes were sequenced in a sample from the full range of these two species. Higherlevels of nucleotide diversity in candidate genes for drought response were present inP. pinaster than in P. halepensis, despite its narrower range in the Mediterranean.Differences across species were also reflected in the haplotype distribution for each treespecies, with P. pinaster showing many different haplotypes at similar frequencies andP. halepensis showing fewer haplotypes with only one that is common or even fixed. The lowlevels of nucleotide diversity in Aleppo pine are more noticeable in its western distributionwhere most genes were fixed or almost fixed for particular haplotypes, a probableconsequence of long-range colonization of the Western Mediterranean from ancient Aleppopine populations in the easternmost edge of its current distribution and a more acute impactof the Ice Ages in this range of the species.Molecular analyses also revealed intense and relatively recent bottlenecks in Aleppo pineas well as a time of split between North-African and Iberian populations of the species wellpredating the Last Glacial Maximum albeit not as old as the one estimated for maritime pine.In contrast, maritime pine seems to harbour large amounts of diversity for these genes dueto a more stable demography; in addition, because of its more mesic distribution, higherenvironmental heterogeneity would have resulted in contrasted selective pressures that mayhave increased general levels of diversity at candidate genes.Using a wide range of neutrality tests, we found some of the candidate genes studied to evolve innon-neutral patterns. Interestingly, two of them showed statistical correlation with temperaturevariables, in particular with extremely high or low temperatures, and may constitute valuabletools for monitoring adaptive genetic diversity in these two Mediterranean pines. Our studyshows that the use of complementary approaches can help capturing different aspects ofthe evolutionary processes that govern molecular variation at both intra- and inter-specificlevels

Autore Pugliese

• Vendramin Giovanni Giuseppe

Tutti gli autori

• S. Mutke; B. Fady; A. Ben Mna; A. Khaldi; M.L. Khouja; S.C. Gonzalez-Martinez; J. Climent; F. Sebastiani; S. Torre; G.G. Vendramin

Titolo volume/Rivista

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Anno di pubblicazione

2011

ISSN

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ISBN

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Numero di citazioni Wos

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Numero di citazioni Scopus

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Settori ERC

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Codici ASJC

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