clear preference to ripe over unripe fruits, were attracted to experimental devices that
emitted the scent of ripe fruits, and rejected dry-frozen fruits that retained the
morphological features of ripe fruits but did not emit scent [82]. In contrast, it should
be noted that in some bat-plant interactions (Phyllostomus hastatus feeding on
Gurania spinulosa), fruit scent does not seem to play a role [95].
Experiments with Old World frugivorous bats have been rarer. Some tried but
could not record reliance on olfaction in fruit foraging [72, 103]. However, these
experiments focused primarily on ethanol and methanol, which are not typical
plant secondary metabolites. In another study short-nosed fruit bats (Cynopterus
brachyotis) were shown to prefer ripe fruits over unripe fruits of two fig species
and to rely primarily on scent to find and identify ripe fruits in an experimental
setting [37]. A follow-up study tested the response of the same Old World bat
species and New World Jamaican fruit bats (Artibeus jamaicensis) to the scent of
fig species from both habitats [38]. Both species were attracted to scent of figs
from their respective habitats, but only the Neotropical species were attracted to
the scent of unknown Paleotropical figs [38]. Since Old World frugivorous bats are
older [89], show similar patterns of olfactory receptor evolution [96], and in most
cases cannot echolocate [91], it is very likely that their ability and tendency to use
their sense of smell for food detection and selection are comparable to that of New
World bats.
All studies which tested the attraction of bats to fruit scent used intact fruits, fruit
extracts, or synthetic mixtures. It is thus unknown whether any individual compound
is particularly attractive to them. While bat-pollinated flowers tend to emit uncommon sulfur-containing compounds [32], bat-consumed fruits tend to emit common
VOCs [37, 38, 40]. Monoterpenes are particularly common in the scent of both
Paleotropical and Neotropical bat-consumed figs and have been proposed to play
an important role in attracting them [38].
3.1.2 Primates
Along with bats and birds, primates are one of the biggest groups of seed dispersers
in tropical systems [104]. Primate seed dispersal plays a pivotal role in a complex
web of interactions between plants, primary and secondary seed dispersers [105,
106]. The fact that most sympatric frugivorous primates overlap in their diets but
vary in their body size, movement patterns, and group size renders them, as a group,
highly effective seed dispersers [107]. For example, since many primate species are
large and arboreal, many species are unlikely to visit early-phase secondary forests in
which trees are still too small to support them. But small-bodied primates like
tamarins (Saguinus spp.) do venture into regenerating forests and thus fulfill
a function similar to that of birds and bats by effectively dispersing seeds into
secondary forests [108].
As opposed to bats, most primates are diurnal and, relative to other mammals,
possess excellent color vision [109, 110]. As a result, visual cues play a role in the
process of ripe fruit detection and selection [111–113], and primate color vision is
likely to have exerted non-negligible selection pressures on the evolution of fruit
color [114, 115].
17 Fruit Scent: Biochemistry, Ecological Function, and Evolution
411
emitted the scent of ripe fruits, and rejected dry-frozen fruits that retained the
morphological features of ripe fruits but did not emit scent [82]. In contrast, it should
be noted that in some bat-plant interactions (Phyllostomus hastatus feeding on
Gurania spinulosa), fruit scent does not seem to play a role [95].
Experiments with Old World frugivorous bats have been rarer. Some tried but
could not record reliance on olfaction in fruit foraging [72, 103]. However, these
experiments focused primarily on ethanol and methanol, which are not typical
plant secondary metabolites. In another study short-nosed fruit bats (Cynopterus
brachyotis) were shown to prefer ripe fruits over unripe fruits of two fig species
and to rely primarily on scent to find and identify ripe fruits in an experimental
setting [37]. A follow-up study tested the response of the same Old World bat
species and New World Jamaican fruit bats (Artibeus jamaicensis) to the scent of
fig species from both habitats [38]. Both species were attracted to scent of figs
from their respective habitats, but only the Neotropical species were attracted to
the scent of unknown Paleotropical figs [38]. Since Old World frugivorous bats are
older [89], show similar patterns of olfactory receptor evolution [96], and in most
cases cannot echolocate [91], it is very likely that their ability and tendency to use
their sense of smell for food detection and selection are comparable to that of New
World bats.
All studies which tested the attraction of bats to fruit scent used intact fruits, fruit
extracts, or synthetic mixtures. It is thus unknown whether any individual compound
is particularly attractive to them. While bat-pollinated flowers tend to emit uncommon sulfur-containing compounds [32], bat-consumed fruits tend to emit common
VOCs [37, 38, 40]. Monoterpenes are particularly common in the scent of both
Paleotropical and Neotropical bat-consumed figs and have been proposed to play
an important role in attracting them [38].
3.1.2 Primates
Along with bats and birds, primates are one of the biggest groups of seed dispersers
in tropical systems [104]. Primate seed dispersal plays a pivotal role in a complex
web of interactions between plants, primary and secondary seed dispersers [105,
106]. The fact that most sympatric frugivorous primates overlap in their diets but
vary in their body size, movement patterns, and group size renders them, as a group,
highly effective seed dispersers [107]. For example, since many primate species are
large and arboreal, many species are unlikely to visit early-phase secondary forests in
which trees are still too small to support them. But small-bodied primates like
tamarins (Saguinus spp.) do venture into regenerating forests and thus fulfill
a function similar to that of birds and bats by effectively dispersing seeds into
secondary forests [108].
As opposed to bats, most primates are diurnal and, relative to other mammals,
possess excellent color vision [109, 110]. As a result, visual cues play a role in the
process of ripe fruit detection and selection [111–113], and primate color vision is
likely to have exerted non-negligible selection pressures on the evolution of fruit
color [114, 115].
17 Fruit Scent: Biochemistry, Ecological Function, and Evolution
411