Fruit odor may have evolved to advertise ripeness to seed-dispersing primates
Fruits are a highly valuable source of food. They are packed with tasty and healthy nutrients and are often characterized by alluring colorful displays and an attractive aroma. Yet it is still unclear which evolutionary forces drove fruits to acquire such a diverse range of different attractive traits.
Moustached tamarins feeding on fruits of Leonia cymosa at the DPZ field station in Peru. Tamarins are among the primates dispersing the seeds of Leonia.
Photo: Adrian Reinehr
In two new studies, scientists from the German Primate Center and their international collaboration partners show that the aroma of ripe fruits may be an adaptation whose function is to attract primates to consume the fruits and consequently disperse their seeds (Scientific Reports, 2015; Journal of Chemical Ecology, 2016).
Immobile plants rely on vertebrates such as primates, birds and bats, which disperse their seeds over large ranges. Fleshy fruits are long known to have evolved to be attractive to these vertebrates. In return to seed-dispersal services, they provide fleshy pulps rich in nutrients such as sugars, fat, protein, vitamins and minerals.
In addition, many fruits acquired traits such as colorful displays, which increase their detectability and attractiveness to vertebrate seed dispersers. Fruit aroma, just like color, may advertise ripeness and quality to seed dispersers who rely strongly on their sense of smell. Yet until recently, this idea has received very little attention.
Primates as seed dispersers
Primates are among the most important seed dispersers in tropical ecosystems. Until recently, they have been considered to be primarily visual animals whose reliance on the sense of smell is limited. Yet several studies from the past years indicate that primates in fact possess a well-developed sense of smell. Thus, fruits that rely on primates’ seed dispersal services may have also evolved to advertise their ripeness and quality through ripe fruit aroma.
Fruit aroma advertises ripeness
Two recent studies, led by scientists from the German Primate Center in collaboration with scientists from Germany, Sweden and Mexico, have tested this hypothesis and provide the first evidence that fruit aroma may be an adaptation whose function is to advertise ripeness to seed-dispersing primates. In one study, the group examined patterns of odor emission from ripe and unripe fruits. Fruit odor samples were collected at the DPZ field station in the heart of the Peruvian Amazonian rainforest.
The results showed that fruits dispersed by primates tend to change their odor profiles upon ripening, thus providing a unique and reliable aroma signature that can allow primates to identify ripe fruits. In contrast, fruits dispersed by birds, which tend to rely on vision rather than the sense of smell, do not change their odor profiles upon ripening. As a result, the odors of bird-dispersed ripe fruits are very similar to those of unripe fruits and fruit aroma is not a reliable ripeness cue in these species. The fact that a substantial change of odor is apparent only in fruits dispersed by primates indicates that it is not a byproduct of fruit maturation that characterizes all fleshy fruits, but rather a trait which is present only in fruits whose main seed disperser is likely to use the odor to identify ripe fruits.
Monkeys identify ripe fruits by their odor
Consequently, a second study attempted to examine how well primates can “work” with the odor signals provided by these fruits. The scientists created several synthetic odor mixtures that mimicked the odors of ripe and unripe fruits, as well as fruits of varying degrees of ripeness. They then conducted experiments with spider monkeys, a species which specializes on ripe fruits and provides seed-dispersal services to many plant species.
The experiments tested whether spider monkeys can discriminate between the odors of ripe fruits and either unripe or partially unripe fruits. The results were clear: spider monkeys excelled in the task. They easily discriminated between the odors and were repeatedly able to use this ability to successfully locate rewards. These results confirm that spider monkeys are capable of relying on the odors emitted by fruits to identify that they are ripe. Furthermore, they can do so even when the odor of unripe fruits becomes increasingly similar to the odor of ripe fruits. Thus, fruit odor is a reliable signal, which allows spider monkeys to identify ripe fruits.
“Taken together, our studies demonstrate for the first time that the pleasant aroma that characterizes many ripe fruits may have an important ecological function of mediating the communication between plants and primates that disperse their seeds”, says Omer Nevo, lead author of both publications. “Primates benefit from the ability to easily and reliably identifying ripe fruits. In return, plants are selected to provide odorous fruits that attract primates and promote seed dispersal.”
Nevo O, Heymann EW, Schulz S & Ayasse M. 2016. Fruit odor as a ripeness signal to seed-dispersing primates? A case study on four Neotropical plant species. Journal of Chemical Ecology. DOI: 10.1007/s10886-016-0687-x.
Nevo O, Orts Garri R, Hernandez Salalzar LT, Schulz S, Heymann EW, Ayasse M & Laska M. 2015. Chemical recognition of fruit ripeness in spider monkeys (Ateles geoffroyi). Scientific Reports 5: 14895. DOI: 10.1038/srep14895.
Dr. Omer Nevo
Behavioral Ecology & Sociobiology Unit, German Primate Center and
Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm
Dr. Susanne Diederich
Communication, German Primate Center
Tel: +49 551 3851-359
The German Primate Center (DPZ) in Göttingen, Germany, conducts basic research on and with primates in the areas of infectious diseases, neurosciences and organismic biology. In addition, it operates four field stations abroad and is a competence and reference center for primate research. The DPZ is one of the 88 research and infrastructure institutions of the Leibniz Association in Germany. www.dpz.eu
Dr. Susanne Diederich | idw - Informationsdienst Wissenschaft
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences