Caracterización genética del Ciprés de la Cordillera (Austrocedrus chilensis (D.Don) Pic. Ser. et Bizzarri) en Argentina: información básica para el uso y conservación de la especie

PASTORINO, MARIO JUAN; GALLO, LEONARDO ARIEL

Esquel

Simposio; I Reunión sobre ecología, conservación y uso de los bosques de ciprés de la cordillera; 2005

CIEFAP

The genetic characterization of the natural populations of Ciprés de la Cordillera is crucial to orientate programs dealing with the use and conservation of its genetic resources. In accordance with the natural range of the species in Argentina, two main environmental gradients were identified: a latitudinal gradient of almost 7º and a gradient of precipitation, from 2,650 to 330 mm/year. Seeds were collected from 595 trees corresponding to 22 populations distributed across the mentioned gradients. Genotypes of the trees were determined at 12 previously identified isozyme markers by analysing at least 8 megagametophytes per tree. Allelic and genotypic frequencies, and subsequently several diversity and differentiation parameters were calculated. The mean allelic richness and the differentiation among populations were small, while the expected and the observed heterozygosities turned out to be moderate. That means a general uniformity among the Argentine populations of Ciprés de la Cordillera, and that the highest levels of variation are within them. On the other side, a general trend towards a distribution of genetic variation along a latitudinal gradient could be recognised (the northerly populations being more variable), but, on the contrary, an association between precipitation and diversity could not be found. The isolated forest patches of the steppe were found to be the most variable. This result, together with the probable adaptation to a precipitation regime of only 500 mm/year, highlights these marginal populations as a valuable source of genetic variation for conservation as well as for breeding purposes.