Fruit-frugivore interactions in a Malagasy littoral forest - Universiteit ...

Intersite comparison
Comparison of fruit characteristics between sites
Morphology
Five out of eleven morphological parameters differed significantly between both study
sites (Table 4). In STL, berries are the dominating type of fruit followed closely by drupes.
In KIR drupes are most abundant followed by berries and capsules. Fruit pulp in STL is
mostly soft and juicy. In KIR the majority of fruits has a rather dry and fibrous pulp.
Remarkable is the large number of odoriferous fruits in STL while in KIR only one third of
the fruits was classified as odoriferous. KIR has more dehiscent fruits and thick-husked
indehiscent fruits than STL where 75% of fruits are indehiscent and thin-husked.
Concerning dispersal type, zoochorous fruits prevail both in KIR and STL, but KIR has
more non-zoochorous fruits than STL. However this difference was no longer significant
after sequential Bonferroni adjustment. There is no significant difference between study
sites for colour, number of seeds, fruit length, fruit mass, seed length and seed
protection.
Chemistry
The chemical composition of mature fruits differed between sites in most chemical
variables except for extractable proteins and sugars. Lipid concentrations were
significantly higher in STL while NDF, ADF, total nitrogen, and procyanidin tannins were
higher in KIR (Table 5). After rigorous adjustment for Type I errors (Rice 1989), there was
only a significant difference for NDF, ADF and tannins.
Comparison of diets of Eulemur and Cheirogaleus between sites
Morphology
Fruits eaten by both lemur species at both sites did not differ significantly in growth form,
number of seeds, fruit length, fruit mass, seed length or seed protection (Table 4).
However significant differences were found with respect to pulp type and the protection of
fruits consumed by Eulemur and Cheirogaleus at both sites. The observed difference
corresponds to the differential availability of fruits with different types of pulp and
protection at both sites.
Even though significantly fewer berries but more capsules were available in KIR than
in STL (Table 4), this difference was not apparent when comparing diets of both lemurs
between sites. Both species seemed to prefer berries and drupes even when these are
less common and harder to find. In contrast, proportions of fruit colours did not differ
significantly between samples eaten by C. medius, although E. fulvus did eat significantly
more brown and green fruits in KIR and more yellow, orange and red fruits in STL. The
proportion of odoriferous fruits eaten by both lemur species was higher in STL than in
KIR, though the difference is not significant in the case of C. medius. KIR also had
significantly more non-zoochorous fruits than STL, but still zoochorous fruits dominate the
fruit diet of both lemur species at both sites.
Chemistry
Except for higher tannin concentrations in fruits consumed in KIR, none of the
concentrations of the plant chemicals differed between fruits eaten by C. medius in STL
and KIR (Table 6). Fruits consumed by E. fulvus contained higher concentrations of fibre
and tannins in KIR than in STL. These results correspond with the biochemical
differences in overall fruit availability between sites. Only the difference between fibre
content remains significant after sequential Bonferroni.
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