But what drives montane biodiversity? The diversity of plants and animals in tropical mountain ranges may have something to do with the stable seasonal temperatures found in the tropics relative to higher latitudes, says a new study by scientists working at the US National Evolutionary Synthesis Center.
The study, based on nearly 200 species of bats, birds, frogs, lizards and snakes, also suggests that tropical montane species may be less flexible than their temperate counterparts in the face of climate change, the authors say. The results appeared last week in Proceedings of the Royal Society B.
Montane regions are home to many species found only there and nowhere else, said lead author Daniel Cadena of the Universidad de los Andes. Steep gradients in elevation and vegetation in montane zones bolster biodiversity by offering many habitats within a small geographical area, Cadena added. "Whereas a lowland area like a rainforest offers the same habitat over a large distance, mountain areas can go from lowland tropical forest, to cloud forest, to pine forest to paramo over a very short distance," said co-author Ken Kozak of the University of Minnesota-Twin Cities.
This environmental heterogeneity makes montane regions especially rich in a pattern of biodiversity called beta diversity, in which the species composition changes as you move from one area to the next. "As you go up a mountain, two elevations may each have ten species but only share five in common," Kozak said.
The researchers wanted to know why montane biodiversity is especially high in the tropics compared to temperate latitudes. To find out, they compiled location and climate data for nearly 200 species of bats, birds, frogs, lizards and snakes living in montane regions in North, South, and Central America.
When they compared mountain ecosystems in tropical and temperate zones, they found that species living in tropical mountains experienced much milder seasonal temperature swings than their temperate counterparts. A frog living at 2000m in the Andes, for example, might experience temperature fluctuations of only 10 degrees between summer and winter, whereas a frog at the same elevation in the Rockies might experience seasonal temperature swings of 40 degrees or more.
Temperatures naturally change as you move up or down a mountain, the researchers explained. But as one moves southward on the globe from the poles toward the equator, seasonal temperature swings begin to stabilize. "Tolerance to extreme temperatures is much narrower for tropical montane species relative to temperate species," Cadena explained.
The researchers also looked at pairs of species that had recently diverged, and found that tropical species stayed more constant in their temperature preferences as one species split into two. "The thermal niches of tropical species tend to be more evolutionarily conserved over long periods of time relative to temperate zone species," Cadena added.
"The inability of many tropical species to adapt to climate conditions at other elevations forces them to stay in the particular zone that they're in, and is a key ingredient that drives the formation of new species" Kozak said. Given the inevitable climatic differences between mountain peaks and valleys, this inability to budge may prevent tropical montane species from dispersing to other elevations. Over time, the isolation leads to populations diverging to form new species, the authors explained.
"In contrast, in temperate mountains, seasonal temperature swings mean that at some point during the year the species at the bottom of a mountain experience the same cold temperatures found at the top of the mountain. So mountain peaks and valleys don't create the same barriers to dispersal which would normally cause the formation of new species," Kozak said.
The same narrow temperature tolerance that seems to boost biodiversity in tropical mountains may also make tropical montane species more vulnerable to global warming, the authors said. "Our results suggest that maybe tropical species are less flexible, and they might be more affected by climate change," Cadena said.
CITATION: Cadena, C., K. Kozak, et al. (2011). "Latitude, elevational climatic zonation, and speciation in New World vertebrates." Proceedings of the Royal Society B. doi: 10.1098/rspb.2011.0720.
The National Evolutionary Synthesis Center (NESCent) is a nonprofit science center dedicated to cross-disciplinary research in evolution. Funded by the National Science Foundation, NESCent is jointly operated by Duke University, The University of North Carolina at Chapel Hill, and North Carolina State University. For more information about research and training opportunities at NESCent, visit www.nescent.org.
Robin Ann Smith | EurekAlert!
Scientists team up on study to save endangered African penguins
16.11.2017 | Florida Atlantic University
Climate change: Urban trees are growing faster worldwide
13.11.2017 | Technische Universität München
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
21.11.2017 | Physics and Astronomy
21.11.2017 | Materials Sciences
21.11.2017 | Health and Medicine