Abstract

FAVELA LARA, Susana. Population variation in the endemic Pinus culminicola detected by rapd. Polibotánica [online]. 2010, n.30, pp.55-67. ISSN 1405-2768.

Pinus culminicola, the dwarf pinyon, is an endangered species endemic to northeastern Mexico, where it grows at the highest altitude of any of the Cembroides group. In order to determine the degree of genetic isolation between populations of P. culminicola and the amount of gene flow between them, samples were obtained from Cerro El Potosi and Sierra La Viga, two localities within its restricted area of distribution in the Sierra Madre Oriental, and analyzed using random amplified polymorphic DNA (RAPD). The five primers tested for the analysis showed banding patterns with very high reproducibility and clear band resolution. These five primers produced a total of 72 distinct bands, 52 of which were polymorphic across the whole sample. The genetic diversity in the two populations was high with a percentage of polymorphism of 53.7% and degree of diversity measured by the Shannon index of 56%. The total variation found between the two populations was 5.98% (P = 0.0001). Most of the variation was found within populations (94.02%). Contrary to expectations, the level of genetic variation found in the two isolated populations was high but differentiation between them low. This suggests that even though this treeline pine has a restricted and fragmented distribution through the Sierra Madre Oriental, gene flow between populations has been sufficient to prevent a dramatic loss of genetic variation and genetic drift.

Keywords : Pinus culminicola; genetic variation; RAPD.