Lemur study suggests why some fruits smell so fruity

It's a nice idea, but hard to prove. However, lemurs sniffing wild fruits in Madagascar reinforce the idea that animal noses have contributed to the evolution of fruity maturity aromas.

The idea sounds simple, says evolutionist ecologist Omer Nevo of Ulm University in Germany. Plants can use tantalizing odors to encourage animals to eat fruit, and so spread around the seeds. But are these smells really advertising or are they just the way fruits feel mature?

For some wild figs and a whole range of fruits in eastern Madagascar, a powerful scent of maturity seems to have evolved to the benefit of the pace, said Nevo and his colleagues on Oct. 3. Progress of science. Many fruits and chemistry of odors suggest that the fruits scattered by the lemurs, with their sensitive noses, change more fragrance than the fruits that depend more on birds having an acute color vision.

Previous studies had detected several species, such as figs. But for a broader look, Nevo and his colleagues analyzed the odors of 25 other types of fruit as well as five types of figs. All grew up in a "truly magnificent" mountainous rainforest conserved as a park in eastern Madagascar, says Nevo.

The researchers ranked 19 plants largely dependent on red-bellied lemurs and other local lemurs for seed dispersal. All these lemurs are red-green daltoniens, which is not ideal for observing ripe fruits among foliage. But researchers who followed lemurs in search of daylight noticed that sniffing fruit was very important for primates.

Nevo does not think lemurs need scents to locate a promising tree. Instead, animals climbing around a tree often snorted fruit before biting into some of them, possibly using the scent as a clue to what to eat now.

Nevo and his colleagues also picked fruits – 434 immature and 428 ripe – and analyzed their odors. The odors proved to be complex, with mixtures totaling 389 compounds. Some ingredients floated in the air in traces, others in strong puffs.

By comparing the odors of mature and immature individual tree fruits, the researchers concluded that the lemur-dependent species for seed dispersal had smells of maturation more than twice as strong as other fruits. An animal with a nose for the fruit should be able to say what is ripe.

On the other hand, plants that depended entirely or partially on birds had fruits whose odor strength had not changed much. In the same way, the chemical composition of their perfumes did not change so much during the maturation, according to an index making it possible to make such comparisons. These fruits have matured; birds and other animals ate them brilliantly. But a radically different perfume was not an important index of maturity. Nevo concludes that the nose of fruit-eating animals, including perhaps the ancestors of human primates, seems to have played a role in the evolution of fruitiness.

According to primatologist Giuseppe Donati of Oxford Brookes University, England, the lemur noses could also play a role in the evolution of the fragrance of the leaves of the Malagasy plant. "On the whole, the plants do not really want their leaves to be eaten, that's the opposite perspective." One of his students analyzes leaf odors emanating from plants in the woolly lemur's territory to determine there is some indication of "do not eat me". fruity "eat that now."