The mystery of the Alpine long-eared bat

                              An Alpine long-eared bat fully airborne , UPV/EHU

The alpine long-eared bat was discovered in the Austrian Alps in 2003; hence its name. Yet later on specimens were found in other milder environments as well, in Croatia, Greece and Crete, and what is more, often close to sea level. Members of the Behavioural Ecology and Evolution Group of the UPV/EHU’s Faculty of Science and Technology studied the distribution and way of life of this species, and found that it forages and reproduces in mostly alpine environments (above the treeline), a unique case among bats. As the biologist Antton Alberdi explained, “the common name of the species not only refers to the place where it came from but describes its nature, too.” Indeed, the researcher concluded that the resources used by the Alpine long-eared bat are the same as the ones used by alpine birds and rodents: in the Pyrenees, for example, it lives at an altitude of between 1,500 and 2,500 metres and hides under rocks, in crevices and on ledges.

Nevertheless, how is it possible that an animal that only lives above 1,500 metres in the Pyrenees can be found at sea level in Croatia? Alberdi was involved in seeking the answer to this question in his PhD thesis. Alberdi identified and quantified the environmental conditions that determine the distribution of the Alpine long-eared bat (Plecotus macrobullaris) to try to understand why this species is restricted to mountain environments and why it can appear at sea level at the same time. After that, in order to see whether the results obtained could be extrapolated to other species, he compared the distributions of 503 vertebrates with those of the bats, and found five vertebrates that have similar geographical distributions to that of the bat: the white-winged snowfinch, the Alpine chough or yellow-billed chough, the wallcreeper, the Alpine accentor and the European snow vole. The distribution of all of them is very broad, from Western Europe all the way to Asia, but they are restricted to the main mountainous areas. He studied their ecological features to see whether they were all following a common biogeographical pattern in order to work out whether they were following a common distribution model.

They need rugged places

The basic ecological features of these vertebrates and those of the Alpine long-eared bat are very similar: they all use rocks (crevices, ledges or crushed stones) as places to hide, and they need open spaces to forage. They have also seen that they can be found in cold mountain environments (in the Alps) as well as in hot ones (in the mountains of Iran and Syria, etc.) and that suggests that the reasons that restrict these species to mountainous areas are not climatic ones: they are linked to topography. In other words, they are not in mountainous areas because they cannot withstand a hot environment, but because high mountain habitats offer them the characteristics they need. In some cases, in Croatia, for example, these conditions can be found at lower altitudes, and that explains why the species can be found at sea level. Furthermore, as they have the capacity to withstand the cold, they can use the alpine habitats that other species cannot exploit and thus avoid competition. In any case, “it cannot be said that the climate does not exert any influence,” said the researcher. “In fact, the climate determines the altitude ranges that each species can live in.”

According to the researcher, to preserve the species it is essential to know everything about them: how they live, why they are present in the places where they are present, etc. In the case of these species, therefore, climate change will not exert such an effect in the future; “more attention will need to be devoted to other factors: human exploitation, pasture use, etc.,” he explained. The researcher believes that the rise in treelines taking place as a result of the decline in the pressure of livestock will affect these species most. Indeed, as the treelines recede, the surface area suited to the habitats of these species will be reduced, because other species will also recede and that way the pressure will increase. They are now working to quantify that effect.

Source: Elhuyar Fundazioa

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Mapping bats could help stop Ebola's spread

Fruit bats (Pteropodidae) are considered the likely host of the Ebola virus. Credit: Satit Srihin

In the fight against Ebola, mapping fruit bat habitats could be one important step, says a geoinformatics researcher at Sweden's Royal Institute of Technology.

Like the Black Death that ravaged medieval Europe, the Ebola virus' progress through remote areas of West Africa is enabled by lack of understanding about the disease, including its causes and transmission.

Mapping technology however will give responders to the crisis in Africa the upper hand in stopping the spread of the deadly disease, says Skog, a researcher in geoinformatics at Sweden's KTH Royal Institute of Technology.

Skog's research has produced a method that medical professionals can use to visualise the geographical distribution of a disease over time. In his research, Skog has explored the relationship between geography and disease distribution in major epidemics of the past, including the Black Death, the Russian Flu pandemic of 1889, the Asiatic Influenza of 1957 and the swine flu. He says the historical data provides a basis for predicting the course of future epidemics and pandemics.

"My research and method can also be used to report the current state of a pandemic, or predict how extensive the spread will be. And where the disease will strike next," Skog says.

In fact, the way in which Black Death spread during the mid 14th, century bears a no small resemblance to today's Ebola epidemic, he says. Both diseases were hosted by small mammals -- black rats and fruit bats, respectively. But ultimately it was humans that enabled its spread.

"The Black Death was very much depending on total lack of knowledge regarding the etiology of the disease and how to avoid further transmission," Skog says. "That is also the case for the mainly remote locations where Ebola now is spread."

Fruit bats are believed to be the natural hosts of Ebola. These bats are among the creatures that residents of rural West Africa hunt for "bush meat." The disease is also spread by the droppings of the bat, and it is believed to have spread to other types of bush meat, as well as monkeys and pigs that are raised for slaughter.

"The local population is getting part of their nourishment from bush hunting, leading to contact with the virus that is transmitted via body fluids," Skog says, suggesting that closer study of the fruit bat could provide vital answers.

"A guess of mine is that the number of infected fruit bats is a determining factor for an Ebola outbreak," he says. "Are there any known factors that may have changed the ecosystem in favor of the bats? Are the bats affected by the virus too? Do fruit bats always carry the Ebola virus or is the virus fatal to them as well? If so the percentage of infected bats will vary over the years also depending on the immunology of the species."

There are a number of geoinformation technology options available to public health organizations that have sent field crews to respond to the crisis. These, Skog says, including equipping field workers with hand-held GPS devices that feed a central database with data and findings regarding locations of bodies, possible infections and diagnosed cases personnel.

"The data can easily be centrally monitored and used for decisions and policies to mitigate the spread," he says. "Using satellite imagery, population centers can be localized. Collected disease data can also be compared and analysed with environmental and climatologic data to support other efforts to control the spread."

For instance, assuming that fruit bats are the reservoir for the ebola virus, Skog says it would be of interest to find out if the first detected cases in an outbreak are located in or close to a fruit bat habitat. "If the environmental and climatologic parameters for fruit bat habitats can be defined, there is a chance these habitats could be mapped using existing map data and satellite or airborne imagery," he says.

"Then risk areas could be monitored and preventive measures could be performed by health authorities. If the natural reservoir is in fact some other animal, positioning the first cases in each outbreak would still give a clue about what to look for."

Source: KTH The Royal Institute of Technology

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'Non-echolocating' fruit bats actually do echolocate, with wing clicks

In a discovery that overturns conventional wisdom about bats, researchers reporting in the Cell Press journal Current Biology on Dec. 4 have found that Old World fruit bats -- long classified as "non-echolocating" -- actually do use a rudimentary form of echolocation. Perhaps most surprisingly, the clicks they emit to produce the echoes that guide them through the darkness aren't vocalizations at all. They are instead produced by the bats' wings, although scientists don't yet know exactly how the bats do it.

In a discovery that overturns conventional wisdom about bats, researchers reporting in the Cell Press journal Current Biology on December 4 have found that Old World fruit bats--long classified as "non-echolocating"--actually do use a rudimentary form of echolocation. Perhaps most surprisingly, the clicks they emit to produce the echoes that guide them through the darkness aren't vocalizations at all. They are instead produced by the bats' wings, although scientists don't yet know exactly how the bats do it.

"I was surprised by the fact that all of the fruit bats we recorded clicked and by the fact that clicks are produced by the wings," says Yossi Yovel of Tel Aviv University in Israel. "Arjan and I still find that hard to believe."

Yovel and postdoctoral fellow Arjan Boonman got their first hint about the fruit bats from a friendly man on a bus in Indonesia who told them about a species of bat that clicked with its wings. As further confirmation, Boonman found a single old paper about a fruit bat with wings that clicked, but it wasn't clear whether those clicks were good for anything.

Rather than look for that one earlier-described species in particular, Yovel suggested something else: "Why not check other fruit bats?"

They selected a total of 19 wild individuals representing three species of fruit bat and different parts of the evolutionary family tree to find that all of them did produce audible clicks with their wings.

"We did all we could to prove it wrong, including sealing the bats' mouths and anesthetizing their tongues, but nothing stopped them from clicking, except for when we interfered with their wing flaps," Yovel says.

Further study showed that two of the three species increased their clicking rate by a factor of three to five or even more when placed in a dark tunnel, implying that the clicks are a natural behavior for the bats.

Tests of the animals' ability to find their way in the dark showed that the fruit bats do have echolocation abilities, although they are poorer than those of other echolocating species. The fruit bats constantly crashed into thick cables, but they could readily learn to discriminate between larger objects: an acoustically reflective black board versus a similar-looking sheet of cloth. Even with large objects, however, the fruit bats didn't exactly come in for a smooth landing, suggesting that their ability is rather rudimentary in comparison to that of bats that rely on clicks produced from their larynxes.

The findings are interesting in light of earlier suggestions that echolocation may have evolved initially for bats to identify and avoid crashing into large objects such as cave walls, Boonman and Yovel say. The new discovery in fruit bats offers insight into how this sophisticated ability in other bats may have evolved over time, although it is unlikely that the laryngeal clicks of those other bats evolved directly from fruit bats' wing clicks. In fact, Yovel says, it's possible that echolocation in bats has independently evolved many times.

"When we study extant species of echolocating bats, we see a developed sensory system that has been adapted and improved over millions of years of evolution," Yovel says. "The rudimentary echolocation of the fruit bat is one example of how the first types of echolocation may have evolved."

Source: Cell Press

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