Genetic diversity of Neckeropsis undulata (Hedw.) Reich populations in old and young forest stands

Deforestation events are rapidly occurring in tropical countries; consequently forest fragments dominate the landscape. Fragmentation in Puerto Rico has shown to negatively affect bryophyte communities in forest remnants. Since bryophytes dispersal abilities are considered limited and fragmentation is expected to reduce genetic diversity of the isolated populations, the genetic diversity of populations of Neckeropsis undulata (Hedw.) Reich. was assessed in old forest stands (impacted by fragmentation) and more recently recovered forest stands (young). Three forest stands impacted by fragmentation were identified from aerial pictures of 1936 Puerto Rico; all stands were located in the Guajataca State Forest. Three forest stands that did not exist in the same location in 1936 were catalogued as young. Five populations were identified in each stand and three individuals collected per population. All samples were carried through the AFLP method for polymorphism identification. Mean within population diversity (Nei's Hs) was 0.257 while the proportion of total genetic diversity among fragments (Fst) was 0.199. When old and young forest stands were compared for within genetic diversity, based on the number of polymorphisms, there was no significant difference (1_O = 43; 2_O = 38; 3_O = 39; 1_Y = 38; 2_Y = 36; 3_Y = 32). The clustering analysis based on genetic distances (Fst) showed that Fragments 1_O, 1_Y, 2_O and 2_Y appear to be more closely related. Fragments 3_O and 3_Y appeared to be more genetically distant to all other sampled fragments.