Material and methodsUltramafic site, topsoil and fungal ecotype isolate descriptionsA map location of the New Caledonia archipelago including sitesused in the current study is presented in Fig. 1. The ultramafic siteswere located in the south of the main island: Bois du Sud (site1, Fig. 1) and Mont Dore (site 2, Fig. 1), and located in the northof New Caledonia: Pindaï Peninsula (site 3, Fig. 1) and KoniamboMassif (sites 4 and 5, Fig. 1). A full description of the ultramaficsites including climate, geology, geomorphology, vegetation struc-ture, site geographical location, soil sampling and mineral analyseshas been previously described in Jaffré (1992). The ultramafic top-soil geochemical analyses from the different sites were carried outas reported in Perrier et al. (2006b) and data are summarized inESM Table 1. The description of Pisolithus albus isolates used in thisstudy is presented in Table 1, which includes isolate codes, site loca-tion of collection, DNA ITS Genbank accession number, ergosterolcontent of mycelium cultivated in vitro (the method is described inmore detail below) and references.