Statistiche spaziali applicate allo studio della biodiversità: Identificazione di breeding zones in specie forestali

We applied geostatistics to previously reported cpSSR haplotype-frequency data from 95 European Norway spruce populations to provide preliminary evidence about the following issues: 1) delineation of genetically homogeneous regions ('genetic zones'); 2) prediction of their haplotype frequencies and definition of related criteria to be applied for provenance identification and certification of seedlots; 3) identification of putative allochthonous stands within the natural range; 4) construction of a continental-scale 'availability map' of the intraspecific biodiversity for Norway spruce. A direct evidence of large-scale geographic structure of cpSSR haplotypes over the European natural range was obtained. The increase of the mean genetic divergence by geographic distance provided a strong hint that geographic distance is a major factor of population differentiation in Norway spruce. Haplotype-frequency surfaces were obtained by applying ordinary kriging to haplotype-frequency sampling data. Cluster analysis carried out on haplotype-frequency surfaces revealed a fair discrimination among 16 breeding zones, with an accuracy of 0.916. Discriminant analysis carried out on the observed haplotype frequencies assigning sampling stands to genetic zones based on their geographic location revealed a fairly high proportion of correctly reassigned stands (0.909), confirming the robustness of the genetic subdivision obtained. Application of geostatistical analysis to genetic marker data, combined with the use of GIS applications, is discussed in relation to breeding activities and to formulation of appropriate conservation strategies for forest tree species.