Flower colour variation and chromosome numbers in the north western distributional area of <i>Turners sidoides</i> (Turneraceae)

Abstract

In the context of the evolutionary studies that are being carried out in Turners sidoides autopolyploid complex (x= 7), a systematic survey was made in the northwestern area (Bolivia) of its distribution. Six populations with salmon flowers and thirty five with yellow ones of the subsp. pinnatifida were found. The distribution of these populations is associated with climatic and spatial variables. The populations with salmon flowers live in the dry forests (Chaco Boreal Biogeographical Province), while yellow flowered populations occur in the inter-andean valleys (Boliviano-Tucumana Biogeographical Province). All the population studied are diploid. The results obtained support the allopatric diversification model of populations with yellow and salmon flowers at the diploid level, probably favoured by the orographic barriers and climatic changes that have arisen during the Andes development and Quaternary glaciations. Moreover, our analysis evidences that the north western area of T. sidoides constitutes an important centre of variation of the subsp. pinnatifida and the major centre of diploids hitherto detected