Variabilidad genética y morfológica y estructuración poblacional en Alstroemeria hookeri subsp. hookeri (Alstroemeriaceae), endémica de Chile

Abstract

The genus Alstroemeria consists of 82, exclusively South American taxa that are distributed mainly in Chile and Brazil. The great economic relevance, that has acquired the Chilean Alstroemeria species, as ornamentals, has aroused great interest in the morphological variability of their flowers and genetic variability in those species with potential economic value. One of these species is Alstroemeria hookeri which has four subspecies, of which A. hookeri subsp. hookeri, is endemic to the Maule and Biobío Regions. Its geographic distribution consists of two ranges, separated by the Coastal Mountain. Thus, there are populations growing in the coastal range, between 5-20 m high, in the provinces of Arauco, Concepcion, Ñuble, and Cauquenes, and populations of the Central Valley, growing between 100-150 m in the Biobío and Ñuble provinces. Preliminary evidence indicated phenotypic differences between coastal and Central Valley populations, principally in colour and shape of the tepals. For this reason, a comparative morphological study was carried out in the complete geographic distribution of this subspecies and a population genetics study was conducted also, especially to determine the levels of population structure. Thirty three floral characters were analyzed through ordination methods. The morphological study shows a slight tendency to separate the populations into two groups, which coincide with the extremes of morphological variation and both geographic ranges, with characters that contribute to this separation. The genetic variability indices were estimated using 17 allozymic loci. We estimated population structure and also carried out an AMOVA analysis. Nei's genetic distances among all population pairs were estimated to obtain a dendrogram showing the genetic similarity relationships. The results indicate high levels of genetic structure and low values of within population genetic diversity were found. The results of AMOVA indicate that the variability occurs mainly among populations. However, these results varied when populations from both geographic ranges were separately analyzed. The genetic similarities are not congruent with the morphological divergence between both geographic ranges, indicating that some populations from Central Valley are more related genetically to some from coastal populations than populations from their own geographic range.