Abstract
ASYMPOSIUM on the "Genetical Structure of Plant Populations" was held at the Brighton meeting of the British Association for the Advancement of Science, on September 13, in Section K (Botany), with Col. F. C. Stern in the chair. Dr. W. B. Turrill (Kew), in an opening paper, denned a population, as the term should be used in biology, as the sum total of individuals of a stated kind, in a stated area, at a stated time. The need of careful determination of ‘kind' and the desirability of preserving proper voucher specimens where there is the slightest possibility of determinations being called in question were emphasized. The extensive and intensive studies now being completed on numerous populations of a limited number of species of seed-bearing plants of the European flora have revealed an unexpected wealth of variation in structure and behaviour. At Kew and Potterne, investigations combining the methods of modern taxonomy, cyto-genetics and ecology are throwing much light upon the make-up of species as population complexes. Attention was directed to the bladder campions (Silene maritima and allied species). In these some variations are common, as degrees of indumentum in S. cucubalus, others are rare, as long cylindrical calyx in S. maritima. Some characters have obvious survival value for definite ecological habitats, such as habit differences between different species or varieties. Spasmodically occurring mutations may be lethal or harmful in various degrees, like ‘poor petal' or ‘split calyx', whereas other variations appear to be neutral at least in some environments. Some variants have a wide geographical range while others are restricted to very local habitats. Hybridization experiments on a very extensive scale have shown genetic differences for most of the variations ; but whereas some characters have a simple genetic basis others can only be explained by the interaction of several genes. Long-isolated populations of relatively small size (as some inland populations ofS. maritima) may show much less variation than is normally found in more widely spread populations. Parallelism between sea-coast and high-mountain populations of different species is very striking.
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Genetical Structure of Plant Populations. Nature 162, 517–518 (1948). https://doi.org/10.1038/162517a0
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DOI: https://doi.org/10.1038/162517a0
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