Isozyme diversity in large and isolated populations of Luma apiculata, (Myrtaceae) in north-western Patagonia, Argentina

CALDIZ, M.S. & A.C. PREMOLI

AUSTRALIAN JOURNAL OF BOTANY

CSIRO PUBLISHING

Año: 2005 vol. 53 p. 781 - 787

0067-1924

We evaluated the amount and distribution of genetic variation in pure populations together with their regeneration gaps, and isolated populations of Luma apiculata (DC.) Burret (Myrtaceae), in northwestern Patagonia. The hypothesis tested is that genetic characteristics will reflect the effects of restricted pollen and seed dispersal as well as the gap-phase regeneration mode of the species. We analyzed 17 populations including pure and dense populations, their regeneration gaps, and isolated populations. Out of 12 resolved putative isozyme loci 67% were polymorphic in at least one population. Analyzed populations were similar in terms of the levels of genetic variation although reduced heterozygosity and elevated inbreeding was measured in regeneration gaps (HO=0.033; FIS=0.710) compared to those in pure and isolated populations respectively (HO=0.033 and 0.111; FIS=0.507 and 0.085). The among-population component of genetic diversity was greater in isolated and faraway populations FST=0.223, and the least differences were in regeneration gaps within the pure forests FST=0.114. Spatial autocorrelation analysis indicated that grouping of similar genotypes exists in the distance class around 4 m. These results suggest that the combination of restricted pollen and seed dispersal, together with the ability of L. apicualta to propagate vegetatively and to regenerate in gaps results in a marked genetic structure at short spatial scales. Additionally heterogeneous seed recruitment in riparian populations results in highly diverse isolated stands.