The chemical ecology of seed dispersal in monoecious and dioecious figs

Abstract

Summary 1.In the nursery pollination system of figs ( Ficus , Moraceae), flower-bearing receptacles called syconia breed pollinating wasps and are units of both pollination and seed dispersal. Pollinators and mammalian seed dispersers are attracted to syconia by volatile organic compounds (VOCs). In monoecious figs, syconia produce both wasps and seeds, while in (gyno)dioecious figs, male (gall) fig trees produce wasps and female (seed) fig trees produce seeds. 2. VOCs were collected using dynamic headspace adsorption methods on freshly collected figs from different trees using Super Q® collection traps. VOC profiles were determined using gas chromatography-mass spectrometry (GC-MS). 3. The VOC profile of receptive and dispersal phase figs were clearly different only in the dioecious mammal-dispersed Ficus hispida but not in dioecious bird-dispersed F. exasperata and monoecious bird-dispersed F. tsjahela . 4. The VOC profile of dispersal phase female figs was clearly different from that of male figs only in F. hispida but not in F. exasperata , as predicted from the phenology of syconium production which only in F. hispida overlaps between male and female trees. Greater difference in VOC profile in F. hispida might ensure preferential removal of seed figs by dispersal agents when gall figs are simultaneously available. 5. The VOC profile of only mammal-dispersed female figs of F. hispida had high levels of fatty acid derivatives such as amyl-acetates and 2-heptanone, while monoterpenes, sesquiterpenes and shikimic acid derivatives were predominant in the other syconial types. A bird-and mammal-repellent compound methyl anthranilate occurred only in gall figs of both dioecious species, as expected, since gall figs containing wasp pollinators should not be consumed by dispersal agents.

The draft genome of tropical fruit durian (Durio zibethinus)

“…It is possible that linking odor and ripening may provide an evolutionary advantage for durian in facilitating fruit dispersal. Certain plants whose primary dispersal vectors are primates with more advanced olfactory systems show a shift in odor at ripening [50][51][52] . Similarly, durian-by emanating an extremely pungent odor at ripening-appears to have the characteristic of a plant whose main dispersal vectors are odorenticed primates rather than visually enticed animals.…”

NON-SMOKY GLYCOSYLTRANSFERASE1 Prevents the Release of Smoky Aroma from Tomato Fruit

“…We can only speculate which natural factor could mediate the selection for 'non-smokiness' of tomato fruit and what physiological or ecological role this could play. For example, the volatile composition of fruits may attract or repel seed dispersing animals (Borges et al, 2008), and in this respect, one can hypothesize that production of "smoky" volatiles in immature fruits, when seeds are unripe, may repel seed dispersers and prevent the fruits from being prematurely eaten. Arresting release of these volatiles in ripe fruits may then, in turn, stimulate their consumption and hence facilitate seed dispersal.…”

Evolutionary Ecology of Figs and Their Associates: Recent Progress and Outstanding Puzzles

“…However, in both cases there are nonzero intercepts on the axis of the wasps, consistent with the interpretation that wasp speciation generally precedes the genetic differentiation and speciation events in the associated figs (Ronsted et al 2005, Weiblen 1999; but see Silvieus et al 2007). It would also appear that even after "speciation," there is a considerable lag in the fig genes sorting (Borges et al 2008;Grison-Pige et al 2002a,b;van Noort et al 1989;Ware et al 1993). We can expect an evolutionary positive feedback involving wasp choice and the chemistry of the attractant volatiles produced by the host (Kiester et al 1984.…”

“…Some ecological circumstances have been suggested to favor different aspects of these tradeoffs, and thereby favor either monoecy or dioecy (Borges et al 2008; …”

“…The basis of host recognition in all fig pollinating wasps is due in large part to chemical attractants that the figs release when receptive (Borges et al 2008, Grison-Pige et al 2002a,b, van Noortetal. 1989, Ware etal.…”