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Genetic studies in populations of Collinsia parviflora Dougl. ex Lindl. (Scrophulariaceae) Krause, Gerda Rosa

Abstract

The Collinsia populations in southwestern British Columbia and northwestern Washington show considerable variation in leaf and flower characters both within and between populations. One of the purposes of this study was to determine the genetic mechanisms controlling some of these characters. Two leaf polymorphisms were studied. They were the presence or absence of purple anthocyanin spots on the surface of the leaves and the presence or absence of a silvery sheen, also on the surface of the leaves. Each was shown to be controlled by a single gene with two alleles. The spotted leaf character was dominant over the unspotted leaf character and the silvery sheen was dominant over the normal green leaf character. Flower size was also studied and shown to be controlled by polygenic inheritance. Two mutant flower colours, white and magenta, are found in this region of study, in addition to the normal blue colour. The inheritance of flower colour was not conclusively determined but the data indicate that two genes may be involved, one controlling the production of the magenta pigment from the colourless precursor and one controlling the production of the blue pigment from the magenta one. Another purpose of this work wa6 to determine the chromosome number of the Collinsias in this area. Both diploid (n=7) and tetraploid (n=l4) counts have been reported. Six populations were studied and all were found to be tetraploid. Finally, the cytological and genetic data were used in conjunction with morphological data to revise the taxonomy of the Collinsias in this region of study. Most authors divide them into two species, C. grandiflora Dougl. ex Lindl. and parviflora Dougl. ex Lindl. However this study indicates that they are only one highly variable species, C. parviflora.

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