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High Genetic Diversity and Clonal Growth in Relict Populations of Olea europaea subsp. laperrinei (Oleaceae) from Hoggar, Algeria

BAALI-CHERIF, DJAMEL ; BESNARD, GUILLAUME

In: Annals of Botany, 2005, vol. 96, no. 5, p. 823-830

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    Title
    • High Genetic Diversity and Clonal Growth in Relict Populations of Olea europaea subsp. laperrinei (Oleaceae) from Hoggar, Algeria
    Author
    • BAALI-CHERIF, DJAMEL. BP44, Laboratoire de Recherche sur les Zones Arides, USTHB/INA, Alger, Algeria and
    • BESNARD, GUILLAUME. Department of Ecology and Evolution, Biology Building, University of Lausanne, 1015 Lausanne, Switzerland
    Document Type
    • Postprint
    Language
    • English
    Published in
    • Annals of Botany, 2005, vol. 96, no. 5, p. 823-830. Oxford University Press
    Other Version
    OAI-PMH Identifier
    • oai:doc.rero.ch:297723
    Summary
    • Background and Aims The Laperrine's olive (Olea europaea subsp. laperrinei) is an endemic tree from Saharan massifs. Its populations have substantially regressed since the Pleistocene and are presently distributed in a fragmented habitat. Long-term persistence of this taxon is uncertain and programmes of preservation have to be urgently implemented. To define a conservation strategy, the genetic diversity and breeding system of this tree have to be investigated. • Methods One hundred and eleven ramets were prospected in the laperrinei populations from the Tamanrasset region, southern Algeria. Genetic polymorphism was revealed at nuclear and chloroplast DNA (cpDNA) microsatellite loci allowing a comparative assessment of the genetic diversity of laperrinei and Mediterranean populations based on bi-parental and maternal markers. Additionally, nuclear microsatellite markers enabled the genotypes to be identified unambiguously. • Key Results Based on nuclear microsatellite data, the total diversity was high (Ht = 0·61) in laperrinei populations and similar to that observed in western Mediterranean populations. A substantial cpDNA diversity (Ht = 0·19) was also observed. Genetically identical ramets originated from the same stump (which can cover >80 m2) were identified in each population. Sixteen per cent of genets exhibited more than one ramet. In addition, several cases of somatic mutations were unambiguously revealed in distinct ramets stemming from the same stump. • Conclusions These data show that highly isolated and small laperrinei populations are able to maintain a high genetic diversity. This supports the existence of relict trees persisting for a very long time (probably since the last humid transition, 3000 years ago). It is proposed that the very long persistence associated with an asexual multiplication of highly adapted trees could be a strategy of survival in extreme conditions avoiding a mutational meltdown due to reproduction in reduced populations