Inter-relationships between type, size and colour of fruits and dispersal in southern African trees

Abstract

The indigenous angiosperm tree flora (1,340 species) of southern Africa was analysed for type, size and colour of fruits and class of biotic dispersal agent (consumer). Species producing fleshy (drupes and berries) and dry (pods, capsules and nuts) fruits account for 52% and 47%, respectively, of the flora. The flora contains about 2.5 times as many berry-producing as drupe-producing species. Based on a log-linear model, fruit type, consumer and fruit size are dependent statistically on each other, whereas fruit colour depends on both fruit size and consumer type acting independently of each other. Drupes and berries are consumed by birds and mammals, with berries being favoured by both birds and mammals. At least 23% (307 species) of the flora apparently depends predominantly on birds for seed dispersal. Drupes and berries favoured by birds tend to be small and brightly coloured (red or black), whereas those eaten mainly by mammals tend to be large and dull (yellow or green). Relatively few fleshy fruits are brown. Pods, capsules and nuts tend to be brown or green. Birds apparently tend to avoid eating green fruits. The notion that green coloration has evolved to enhance crypsis and/or to signal unpalatability in unripe fruit to reduce premature exploitation is questioned. Green as a cryptic colour is incompatible with the demonstrated mammalian selection of this colour, while to function aposematically a stronger contrast colour may be required.

Reproductive traits of tropical rain-forest trees in New Caledonia

“…The proportions of fruit colours appear to be similar to data from elsewhere in Australasia (Willson et al 1989), but distinct from areas such as southern Africa, where there are higher proportions of green and brown fruits, a factor attributable to the importance of large mammals (Gautier-Hion et al 1985, Knight & Siegfried 1983. The proportion of functionally fleshy fruits we recorded is similar to that observed in other tropical regions, and elsewhere in Australasia.…”

Diversity of functional traits of fleshy fruits in a species-rich Atlantic rain forest

“…This study revealed many similar trends and subtle differences with other studies (Knight & Siegfried 1983, Wheelwright & Janson 1985, Herrera 1987, Dowsett-Lemaire 1988, Willson et al 1989, Corlett 1996, Nakanishi 1996. As reported for other floras (Herrera 1987, Corlett 1996, the frequency distributions of seed number, fruit and seed sizes are highly skewed to the right.…”

“…As reported for other floras (Herrera 1987, Corlett 1996, the frequency distributions of seed number, fruit and seed sizes are highly skewed to the right. Similarly, the fruit color spectrum found at Saibadela parallels those found in other communities, with black and red being the most common colors (Knight & Siegfried 1983, Willson et al 1989, Corlett 1996. The predominance of black over red in bird fruits seems to be a characteristic feature of most plant communities (Wheelwright & Janson 1985, Knight & Siegfried 1983, Nakanishi 1996, but it is different from savanna communities (Donatti et al 2007).…”

“…Similarly, the fruit color spectrum found at Saibadela parallels those found in other communities, with black and red being the most common colors (Knight & Siegfried 1983, Willson et al 1989, Corlett 1996. The predominance of black over red in bird fruits seems to be a characteristic feature of most plant communities (Wheelwright & Janson 1985, Knight & Siegfried 1983, Nakanishi 1996, but it is different from savanna communities (Donatti et al 2007). Worth mentioning is the greater proportion of green color among bird fruits in Saibadela when compared to other tropical (Wheelwright & Janson 1985), subtropical (Long 1971), and temperate communities (Nakanishi 1996) (7.1% vs. 0-4.8%).…”

Padrões morfológicos de diásporos de árvores e arvoretas zoocóricas no Parque Estadual de Itapuã, RS, Brasil

“…Este padrão é também comum em outras regiões subtropicais como em Hong Kong (Corlett 1996) e em localidades na Austrália (Willson et al 1989), em que as aves representam importante papel como dispersoras. Fogem a este padrão as regiões de cerrado (Galetti 2001) e de savana africana (Knighth & Siegfried 1983), nas quais se verifica maior freqüência de frutos mamaliocóricos, associados à presença de mamíferos de grande porte.…”