Contrasting genetic diversity of tree species in Spain: from Tertiary relicts to domestication

U. Lopez de Heredia, J. J. Robledo-Arnuncio, P. Fuentes-Utrilla, M. Valbuena-Carabaña, L. Gil


The diversity of forest ecosystems depends on the species richness, but also on the genetic variability at the intraspecific level. In this work, we investigate the contrasting patterns of genetic diversity among Spanish tree species, illustrated by means of four case studies. Combining molecular, palaeobotanical and historical information, we identify the main factors that explain the observed genetic variability of some representative taxa: (1) isolation of relict tree populations in island ecosystems of Balearic evergreen oaks and Canary Island Pine; (2) existence of glacial refugia for Pinus sylvestris, Quercus petraea and Q. pyrenaica; and (3) domestication and spread of Ulmus minor by Romans throughout Western Europe. These situations represent a gradient in the observed values of genetic diversity: Pinus canariensis and the evergreen oaks show high levels of genetic diversity in the Canary Islands and the Balearics, respectively; P. sylvestris, Q. petraea and Q. pyrenaica have also maintained high levels of genetic diversity, even under intensive, longstanding human management. Finally, U. minor genetic variability has been greatly affected by human activities, Dutch elm disease, and the interaction between the two. Understanding how the genetic diversity is maintained and how it is geographically distributed is basic to develop sound conservation policies and sustainable forest management strategies.

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DOI: 10.5424/srf/2005143-00922