March 4, 2014
Study Of Olfaction In Fruit-Eating Bats Could Shed Light On Our Own Sense Of Smell
Brett Smith for redOrbit.com - Your Universe Online
While scientists know that a superfamily of genes inside olfactory receptors is responsible for our sense of smell – we still don’t know the mechanism behind the interpretation of odor molecules into a particular smell.
The study authors said their work emphasizes the importance of looking at diversity in nature to determine genome functions and evolutionary history in mammals.
"We knew that animals that live in various ecological environments--whales, bats, cows--have evolved different suites of olfactory receptors," explained study author Liliana Davalos, an evolutionary biologist at Stony Brook University in New York. "That suggests that the ability to smell different odors is important for survival."
"This study provides new insights into the mechanisms that have allowed bats to diversify their diets so extensively," said study author Simon Malcomber, a program director in the National Science Foundation's Division of Environmental Biology.
The researchers said they wanted to know if the development of other sensory systems, transformations in diet, or the random accumulation of transformations through time drove the progression of olfaction in mammals.
"Bats offer a prime opportunity to answer this question," Davalos said. "They've evolved new sensory systems such as echolocation, and various bat species eat very different foods, including insects, nectar, fruit, frogs, lizards and even blood."
After a genetic analysis of thousands of olfactory receptors from various bat species and analyzing an evolutionary tree including every one of the species, the scientists found distinctive patterns of olfactory receptors among bats that have fruit as a major part of their diet.
The researchers discovered that the genetic patterns for olfaction have arisen two times, once amongst New World leaf-nosed bats that mostly eat figs and another time amongst Old World fruit bats. These bats feed on a wide variety of fruits, including figs, guavas, bananas and mangoes.
The study team also found that the olfactory receptors in these two different groups of bats are similar, however distinction repertoires have arisen in different ways in New World and Old World bats.
Davalos said this means that independent mechanisms must have affected this part of the bat genome in response to the challenge of finding fruit at night.
In a related study published in February, Duke University researchers revealed that Madagascar sucker-footed bats are primitive members of a group of bats that evolved in Africa and ultimately went on to flourish in South America. The study showed that the sucker-footed bat family is at least 36 million years older than previously known.
Today, the sucker-footed bats consist of two species, Myzopoda aurita and M. schliemanni, which live in Madagascar. Unlike other bats, sucker-footed bats don’t cling upside-down to cave ceilings or branches. Instead, they roost head-up, often in the furled leaves of the traveler’s palm, a plant in the bird-of-paradise family. Scientists previously thought the pads held the bats up by suction, but recent research has shown the bats instead rely on wet adhesion to stay upright.