MODES OF EVOLUTION IN ORNAMENTAL GEOPHYTES

1. Selection applied consciously by the growers (selective breeding) - this for traits of interest to them.
2. Unconscious selection brought about by the fact that the plants concerned were transported from their original wild environments into new (and usually very different) human-made environments. The shift in the ecology leads to shifts in selection pressures. Numerous adaptations vital for survival in the wild, lose their fitness under the new set of conditions. New traits are automatically selected for, in response to the introduction into cultivation, leading to the build-up of characteristic domestication syndromes, each fitting the specific agricultural or gardening system provided by the domesticator.

The role of unconscious selection in the evolution of crop plants has been evaluated by several authors (Darlington, 1963, 1973; Zohary, 1969, 1984; Harlan et al., 1973; Hammer, 1984; Heiser, 1988). It is now widely accepted that this type of selection shaped many of the traits that characterize plants under domestication. Indeed this approach has already considerably assisted crop-plant evolutionists in their reconstruction of the evolution of grain crops and fruit trees (for review see Zohary and Hopf, 1993, pp. 17–18, 87–88, 184–187). In comparison ornamental bulbs and corms have not yet been critically evaluated. This paper aims to close this gap. It takes note of the adaptations of the Mediterranean and Near Eastern geophytes in their wild environments, and it traces the main ‘ecological shifts’ introduced by the transfer of these ornamental plants into cultivation. It outlines the evolutionary consequences expected to be brought about in response to these changes.

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