We used isozymes (16 loci in 11 enzymatic systems) from Laelia speciosa, an endemic and endangered epiphytic orchid of Mexico, to assess the genetic diversity and population genetic structure in nine populations distributed along its geographic range, as well as to detect those populations that are genetically unique and therefore deserve high-priority protection. On average, the genetic diversity was high (percentage of polymorphic loci, P(p) = 76%, mean number of alleles per locus, A = 3.34, the average observed heterozygosity H(O) = 0.302, the average expected heterozygosity H(E) = 0.382). Moderate levels of inbreeding ( f = 0.216, 95% confidence interval = 0.029-0.381) were found. Low levels of genetic differentiation were observed among populations ((p) = 0.040); however, there was a significant correlation between geographic and genetic distances among the populations (Mantel test: r(2) = 0.43, P < 0.05). Populations located within the same mountain range were genetically more similar. Private alleles were found, so proper management requires protection and maintenance of genetic diversity throughout its range. In case of reintroduction, we suggest using individuals propagated from seeds from as many capsules as possible, from close populations. An ex situ conservation strategy also is proposed.

Laelia speciosa is an endangered epiphytic orchid. The effects of various media components on germination of L. speciosa were evaluated. Pods were collected at 4, 7, and 9 months following hand-pollination, and seeds were germinated on Murashige and Skoog (MS) media with 30 g l -1 sucrose and five concentrations (0.0, 0.04, 0.22, 0.44, and 2.22 lM) of benzyladenine (BA) under light and dark conditions. Gibberellic acid (GA 3 ; 0.0, 0.29, 1.44, 2.89, 14. 43 and 28.87 lM) with naphthaleneacetic acid (NAA; 0.0, 0.54, 1.34, 2.69, and 5.37 lM) were evaluated for in vitro subcultivation. MS medium with 30 g l -1 sucrose was effective for germination. The effects of BA and light on germination of L. speciosa seeds differed with pod maturity. All mature seeds germinated using 0.44 lM BA and light. The highest frequency of germinated seedlings (60%) was obtained using mature seeds grown on MS medium without BA and under light conditions. For subculture, MS with 30 g l -1 sucrose, 2.69 lM NAA, and 0.29 lM GA 3 was effective. Plantlets of 5 cm in length were transplanted to the greenhouse, and a 77.5% of survival rate was obtained. A successful protocol for micropropagation by seed germination will contribute to the development of a sustainable management program for L. speciosa.

are unimportant in the determination of the species geographic ranges 8-10. However, several studies have demonstrated that the inclusion of biotic interactions in ENMs improves the performance of these models, both at local and regional scales 1,9,11-13. Epiphyte plants are a group that exemplifies the importance of biotic interactions. Such species establish and complete their entire life cycle on the bark of trees, and therefore the distribution of their host tree species strongly influence the distribution of these plants 8,14. However, despite the essential role that biotic interactions play in determining the distribution of some species, very little is known about the functioning of these ecological relationships 5,8,15. Moreover, the importance of the interactions that occur among species at the macro-scale is still subject of debate 8,16. It is expected that climate change will modify the range of an important number of species 17-20 , which may modify the composition of local communities, and may create transient communities that could be dominated by generalists species 21-23. To understand the possible effects of climate change on species distributions and ecosystem relationships, and to promote biodiversity conservation, it is essential to consider all the important drivers of the distribution of species when projecting future changes 24. For species that are highly dependent on biotic interactions, it is necessary to understand the effect of these interactions on their distributions 25,26. For example, currently interacting species may no longer occupy the same areas in the future as a result of climate change, because they could migrate at either different speeds or directions 26-28. Some biotic interactions, such as predation, competition and mutualism, are especially important for the maintenance of biodiversity 29,30 , and they can be decisive in determining the response of interacting species to climate change 11. Biotic interactions are key for evolutionary and ecological processes and mediate the responses of some species to climate 21. Similarly, climate can affect the direction, frequency and intensity of the interactions. Thus, understanding the complexity of the relationship between climate and biotic interactions is essential in order to predict the future habitat distribution of some species, especially those strongly dependent on these interactions. The establishment and abundance of epiphytic plants is largely determined by the microclimatic conditions provided by their host tree, like a protecting shadow and support well above the ground 31,32. This host-guest relationship therefore largely determines the distribution of these epiphyte species 32. Future changes in the distribution of host species due to climate change may thus act to reduce the distribution of epiphytes 11,33. Moreover, these species live in tropical forests, a habitat under particular threat due to changes in both climate and land use 34. Finally, these species are very sensitive to variations in temperature and pr...

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