Seed Color Adaptation

In a report (Brayton and Capon 1980) on variations in seed morpology among 19 populations of the annual Salvia columbariae Benth., it was noted that a high frequency of colour matching occurs between seeds and soil at individual population and sites. Seed and soil colours ranged from grey to light brown and red-brown. During an intervening 8-year period, the constancy of seed colour in 26 populations was verified. Seed colour was most uniform in relatively small populations (25-50 plants) that occupied sites with a single soil colour. In large populations (> 500 plants) that cover patchy areas of mixed soil types, seed colour was variable with no localized patterns of seed-soil colour matching. Close correspondence between seed and soil colour in small populations suggested that natural selection in favour of seeds least easily seen by granivores was operative. The results of field and laboratory experiments supported the selection hypothesis.

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