FRUIT CONSPICUOUSNESS IN SOME NEW-ZEALAND COPROSMA (RUBIACEAE) SPECIES

Fruit conspicuousness, defined as the magnitude of the colour differen ce between a fruit and its background, is one feature of fleshy fruits that may influence frugivory and hence seed dispersal. Quantitative c olour determinations using CIE [1976] L() a(*) b(*) (CIELAB) values b ased on human colour vision were obtained by the use of reflectance sp ectroscopy for ripe fleshy fruits, leaves and bark of 33 species of Co prosma in New Zealand. Amongst the three plant parts assessed, colour differences were greatest between fruits and foliage. Fruits with redd ish or black hues were significantly more contrasted with their foliag e than other fruit colour groups (white, bluish, polymorphic). Fruit c olour contrasts against leaf were significantly and positively correla ted with those of fruit against bark. Overall colour differences betwe en fruit and leaf were significantly greater in species with larger le aves. There was no trend for fruits to be more conspicuous against the ir own leaves, as compared with leaves of other species, and fruit/fol iage colour differences were unrelated to ecological factors such as a ltitude, latitude, and habitat. Extrapolation of these results, based on human colour characteristics, to natural dispersers of Coprosma fru its (birds and small lizards) will depend on the as yet unknown degree of similarity amongst these vertebrates and humans in spectral sensit ivities and the ability to discriminate between colours.