Nocturnal scent in a ‘bird-fig’: A cue to attract bats as additional dispersers?

Abstract

The plant genus Ficus is a keystone resource in tropical ecoystems. One of the unique features of figs is the diversity of fruit traits, which in many cases match their various dispersers, the so-called fruit syndromes. The classic example of this is the strong phenotypic differences found between figs with bat and bird dispersers (color, size, presentation, and scent). The ‘bird-fig’ Ficus colubrinae represents an exception to this trend since it attracts the small frugivorous bat species Ectophylla alba at night, but during the day it attracts bird visitors. Here we investigate day to night changes in fruit scent as a possible mechanism by which this ‘bird-fig’ could attract bats despite its fruit traits, which should appeal solely to birds. Analyses of odor bouquets from the bat- and bird-dispersal phases (i.e. day and night) differed significantly in their composition of volatiles. We observed a significant increase in relative amounts of sesquiterpene and aromatic compounds at night while relative amounts of two compounds of the fatty acid pathway were significantly higher during day. This finding raises the question whether Ficus colubrinae , a phenotypically classic ‘bird-fig’, might be able to attract bat dispersers by an olfactory signal at night. Preliminary observations from feeding experiments which indicate that Ectophylla alba is capable of finding ripe figs by scent alone point in this direction. However, additional behavioral experiments on whether bats prefer the ‘night-bouquet’ over the ‘day-bouquet’ will be needed to unequivocally answer this question.

Multiscale variability in nutrients and secondary metabolites in a bat‐dispersed neotropical fruit

“…For instance, birds are less deterred by alkenylphenols than bats (Maynard et al, 2020 ). Birds typically defecate seeds while being perched, while bats defecate during flight, offering different, and perhaps complementary, seed dispersal patterns across a range of microclimates and dispersal distances (Mello et al, 2011 ; Ripperger et al, 2019 ).…”

Social behaviour and vocalizations of the tent-roosting Honduran white bat

“…La Tirimbina Biological Reserve contains fragments of secondary tropical wet forest and has been the centre of detailed investigations on the natural history of E . alba in the last decade [ 8 , 10 , 12 , 14 , 16 – 18 ]. The first E .…”

“…We monitored two groups of E. alba in La Tirimbina Biological Reserve, Heredia Province, in the North-East of Costa Rica (10˚26´N, 83˚59´W) from May to June 2010. La Tirimbina Biological Reserve contains fragments of secondary tropical wet forest and has been the centre of detailed investigations on the natural history of E. alba in the last decade [8,10,12,14,[16][17][18].…”

Aeroscapes and the Sensory Ecology of Olfaction in a Tropical Dry Forest

“…The upshot is that daytime canopy conditions are suboptimal for anemotaxis in the service of frugivory and seed dispersal, which may explain why so-called "bird-fruits" in the upper canopy emit little scent (Gautier-Hion et al, 1985;Howe, 1986;Lomáscolo et al, 2010;Valenta et al, 2018;Valenta and Nevo, 2020). Some angiosperm plants, including Ficus and Nicotiana, exhibit diurnal rhythms in fruit and flower chemistry (Raguso et al, 2003;Borges et al, 2011;Burdon et al, 2015;Ripperger et al, 2019;Balducci et al, 2020) timed to maximize their availability and attractiveness for pollinators and seed dispersers. These diurnal rhythms may have evolved in response to diurnal patterns in air movement, such that compounds produced during the day may be heavier and more robust against turbulent conditions than those produced at night, which may be lighter and more easily propagated under calmer conditions (Alberts, 1992;Muller-Schwarze, 2006).…”