Genetic analysis and conservation of 31 surviving individuals of a rare New Zealand tree, Metrosideros bartlettii (Myrtaceae)

Metrosideros bartlettii (Myrtaceae) is a distinctive and extremely rare tre e, endemic to New Zealand, first discovered in 1975. Prior to this study, a total of 19 adult individuals of the species had been reported; these are located in three small forest remnants in the far north of the North Island of New Zealand. Here we describe a total of 31 adult M. bartlettii at the three sites, including 12 individuals newly discovered by us. We analyse th e genetic diversity of the species, using microsatellites to examine the ch loroplast genome and amplified fragment length polymorphisms (AFLPs) to mon itor nuclear variation. The results clearly demonstrate that hi. bartlettii is a unique species, distinct from its two closest relatives M. robusta an d M. excelsa. Analysis of genetic diversity within the 31 remaining individ uals of M, bartlettii showed an average heterozygosity (< H >) of 0.18 and a proportion of polymorphic genes (< P >) of 0.44. Population structure, as shown by 286 AFLP loci, varied between the three geographical sites; the s ite with fewest individuals, containing two trees, showed some separation f rom the populations at the other two locations. These two latter sites, by contrast, had highly overlapping AFLP population diversity profiles. The im plications of these results for conservation of the species are discussed.