Genetic variation in natural populations of Austrocedrus chilensis, a cypress of the Andean-Patagonian Forest

PASTORINO, MARIO JUAN; GALLO, LEONARDO ARIEL; HATTEMER, HANS H.

BIOCHEMICAL SYSTEMATICS AND ECOLOGY

Elsevier

Año: 2004 vol. 32 p. 993 - 1008

0305-1978

Austrocedrus chilensis (D.Don) Pic. Ser. et Bizzarri is a dioecious member of the Cupressaceae distributed naturally over a narrow strip that runs parallel to the Cordillera de los Andes from 32º 39’ S in Chile to 43º 44’ S in Argentina. This range is markedly fragmentary and therefore considerable genetic differentiation is expected. The genotypes of 387 trees from 15 Argentinean populations were determined at 12 isozyme marker loci, half of which were virtually monomorphic. The number of alleles per locus (A/L = 1.51) and the allelic diversity (v = 1.16) were small, while the expected (He,) and the observed heterozygosities (Ho) resulted in moderate level (0.143 and 0.134 respectively). The differentiation between populations was small (d = 0.043; FST = 0.066), and a trend in the distribution of genetic variation along a latitudinal gradient was shown, the northerly populations being more variable. The marginal populations from the steppe were found to be the most variable. The pattern found matches with several small refuges during the Last Glacial Maximum situated eastward from the Cordillera de los Andes in xeric environments and mostly in northern locations of the present range, followed by a considerable rate of population growth.