Do rare pines need different conservation strategies? Evidence from three Mexican species

Mexico is a major center of diversity for the genus Pinus as it has the gre atest number of species in the world. Many species are now restricted to Me xico, and some are represented by very small populations and are in danger of extinction. In this study we examined allozyme variation in three rare s pecies of Mexican pines: Pinus pinceana Gord., Pinus lagunae M.F. Passini, and Pinus muricata D. Don, with the objective of providing conservation gui delines. The three species had relatively high levels of genetic variation with mean expected heterozygosities of 0.373, 0.386, and 0.346 for P. pince ana, P. lagunae, and P. muricata, respectively. We found marked differentia tion among populations and significant inbreeding within populations of the three species. These values are larger than the range reported for most co nifers and suggest that conservation strategies of these rare pines require focusing on the viability of several populations. Given that our knowledge about the demographic status of the three species is scarce, we propose a mixed strategy of conservation. For P. lagunae, we propose an in situ strat egy, whereas for P. pinceana and P. muricata we propose an ex situ strategy of conservation until permanent protection can be provided for several of their populations.