Fruit Colour in Relation to the Ecology and Habit of Coprosma (Rubiaceae) Species in New Zealand

Publisher Website
Google Scholar
Abstract
Analysis of fruit colours for the 58 Coprosma taxa in the New Zealand biogengraphic region shows that 55% have fruits of varying shades of red. The remainder are either bluish (17%), whitish/cream (14%), dark purple to black (7%) or polymorphic (7%). New Zealand Coprosma species exhibit a greater colour range and a lower proportion of red coloured fruits than those of other countries where the genus occurs. Fruit colour was examined in relation to morphological features such as fruit size, leaf size and life form, and with respect to ecological features such as geographic distribution and habitat. Fruit colour is significantly correlated with leaf size, with larger leaved species characteristically having reddish fruits. It is suggested that where green foliage forms the predominant background, reddish fruits provide the greatest colour contrast and therefore maximum conspicuousness, particularly to diurnal avian dispersers. A similar explanation, together with the limited range of dispersers and the brief period available for fruit removal before winter snow, may account for the predominance of reddish fruits over other fruit colours at higher altitudes. Nonred fruit colours are significantly more frequent in small-leaved Coprosma species at low altitudes, where there is a greater diversity of dispersers, particularly small lizards, and strongly nectarivorous birds. Moas, the now extinct New Zealand ratites, are also suggested as possible previous dispersers of non-red fruits.