| Summary: | Relations between individual trees hypothesized to be representative of Picea enqelmannii and P. sitchensis and putative hybrids in southwestern British Columbia were examined using several morphological and anatomical variables measured on cones, needles, and twigs. 36 variables were selected that had an inter-individual variation that exceeded intra-individual variation. Such relative variation suggested that the variables selected were more genetically than developmentally variable. These variables were measured on 640 trees.
Patterns of inter- and intra-individual variation of these variables were examined with multivariate analyses. Similar patterns of intra-individual variation with respect to position in the canopy were detected regardless of the age of the tree or the species, suggesting that intra-individual variation in Picea is not necessarily a function of the environment extrinsic to the individual. Further, the two hypothesized taxa were not especially different with respect to the pattern of intra-individual variation. In an inter-individual context, the intra-taxonomic variation was shown to be larger than inter-taxonomic variation. Inter-individual variation attributed to the hypothesized taxa was smaller than intra-population variation. Inter-taxonomic variation was only 25 percent larger than intra-individual variation. Further, the hypothesized taxonomic polarity of the data was not co-incident with the actual polarity of the data. What taxonomic structure emerged was evident only as the extremes of a continuum of variation over a large geographic area reflecting large environmental variation, suggesting that recognition of two taxa of Picea in southwestern British Columbia may not be appropriate or practically feasible. From the evidence available here, it is not possible to attribute the pattern of variation to hybridization followed by introgression or to the differentiation of a single, large polymorphic taxon.
The pattern of inter-individual variation was only partially correlated with regional and local scales of geographic and environmental variation. Local patterns of variation were not co-incident in 16 separate geographic areas. The relation of the pattern of variation in nursery grown trees with respect to regional scales of geographic variation was not co-incident with the patterns of variation in naturally grown trees from the same area of origin. This variability of relations suggests that inter-individual variation is probably attributable to processes operating at an extremely local scale.
Implications from these conclusions are presented and discussed with respect to the systematics of Picea and the utilization of Picea in forestry and tree improvement programmes. === Science, Faculty of === Botany, Department of === Graduate
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