Coniferous trees form the dominant plant species in many alpine landscapes, which are subject to climate change and other anthropogenic factors. Alpine coniferous tree species in the Italian Alps may be responding to climate change by adapting to the modified environmental conditions or by migrating to more suitable habitats. Our goal is quantify and understand the standing adaptive genetic diversity in alpine conifers so that we may obtain a baseline reference to monitor genetic change in populations. Moreover, this study will provide useful information for forestry management, such as diagnostic tools for assisted migration according to the species potential distribution. We focus on five species: Pinus cembra L., Larix decidua Mill., Pinus mugo Turra, Abies alba Mill and Picea abies (L.) H. Karst.
To begin, we have studied the level of DNA sequence polymorphism in four species (Picea abies was investigated in a prior study). For each species, 12 individuals were sampled from several diverse mountain locations, such as Pyrenees, Massif Central, Alps, Apennines and Carpathian. Nearly 800 candidate genes were resequenced to identify single nucleotide polymorphisms (SNP) in the four species. Because Sanger sequencing primers were derived from loblolly pine (Pinus taeda L.) a higher percentage of amplicons could be resequenced in the pines than fir or larch. In Pinus mugo and Pinus cembra 4500 and 2500 SNPs were discovered, respectively. In Larix decidua and Abies alba 1800 and 1300 SNPs were discovered, respectively. We are currently estimating measures of nucleotide diversity and performing tests of neutrality with these sequence data.
The second aim of the research is to determine the complex patterns of the adaptation to changing environment by performing population genetic analyses in the four species. Genotyping chips for the four species will be designed and genotyping will be conduced for 1000 trees per species in Italian Alps. The sampling sites have been identified to capture the full spectrum of adaptive genetic diversity and to study the possible interaction among species that share the same environment.