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Aquesta setmana acaba de publicar-se en línia a Journal of Heredity, que edita la prestigiosa American Genetic Association l'article del nostre company del BioC Jordi López-Pujol amb un grup d'investigadors coreans sobre diversitat genètica d'un parell d'orquídies comuna/rara (Oreorchis patens/Oreorchis coreana), per mitjà d'electroforesi d'al·loenzims.
Mentre que l'espècie comuna presenta nivells de diversitat no preocupants, la variació genètica a O. coreana és nul·la. Des d'una perspectiva de conservació a llarg termini, aquesta manca de diversitat va associada a una raresa extrema i a petites mides poblacionals i l'espècie s'enfronta a un elevat risc d'extinció.
Les orquídies estudiades creixen als sistemes muntanyosos de Corea del Sud i a l'illa de Jeju
MI YOON CHUNG, JORDI LÓPEZ-PUJOL, MASAYUKI MAKI, KI-JOONG KIM, JAE MIN CHUNG, BYUNG-YUN SUN & MYONG GI CHUNG (2012)
Genetic Diversity in the Common Terrestrial Orchid Oreorchis patens and Its Rare Congener Oreorchis coreana: Inference of Species Evolutionary History and Implications for Conservation
Journal of Heredity 2012 doi:10.1093/jhered/ess032
Abstract
We hypothesized that the main Korean mountain ranges provided many refugia for boreal plant species, where they likely found relatively stable habitats and maintained large population sizes. Under this scenario, high levels of genetic variation and low degree of differentiation among populations within these species were anticipated. To test this hypothesis, we examined levels of allozyme diversity (17 loci) in 12 populations of the common terrestrial montane orchid Oreorchis patens from the main ranges in Korea and 4 populations of its rare congener O. coreana, which is restricted to the Korean island of Jeju. As expected, O. patens harbored high levels of genetic variation within populations (%P = 62.8, A = 1.96, Ho = 0.211, and He = 0.237). Allele frequency differences among populations were low (Fst = 0.075), and the species also displayed a significant correlation between pairwise genetic differentiation and geographical distance. All these results suggest that extant populations were founded by multiple genetically diverse individuals and that most of this initial diversity would have been maintained in the stable mountainous conditions during Quaternary climatic oscillations. In contrast, we were unable to detect any genetic diversity in O. coreana, suggesting that contemporary populations likely originated from a single ancestral source population that had lost all genetic variability. From a long-term conservation genetics perspective, extreme rarity and small population sizes, coupled with its apparent genetic uniformity, place O. coreana at a high risk of extinction. Thus, both in situ and ex situ conservation efforts should be of particular importance for this species.
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