This innovative work by Graduate Student Ruscena Wiederholt and Associate Professor of Biology Eric Post examined how El Niño warming affected the abundance of four New World monkeys over decades. The research will be published on 28 October 2009 in the Royal Society journal Biology Letters, a fast-track journal of the Royal Society of London.
Wiederholt and Post decided to concentrate on the way the oscillating weather patterns directly and indirectly influence plants and animals in the tropics. Until the research by Wiederholt and Post, this intricate network of interacting factors had rarely been analyzed as a single system. "We know very little about how climate change and global warming are affecting primate species," explains Wiederholt. "Up to one third of primates species are threatened with extinction, so it is really crucial to understand how these changes in climate may be affecting their populations."
The scientists focused on the large-bodied monkeys of South America, which are highly threatened. Choosing one species from each of the four genera of Atelines, Wiederholt and Post examined abundance trends and dynamics in populations of the muriqui (Brachyteles hypoxanthus, formerly B. arachnoides) of Brazil, the woolly monkey (Lagothrix lagotricha) in Colombia, Geoffroy's spider monkey (Ateles geoffroyi), which was studied on Barro Colorado Island in Panama, and the red howler monkey (Alouatta seniculus) in Venezuela.
Detailed ecological information was not available on each of the forests in which the target species live, so the team used information from Barro Colorado Island -- a lowland, moist, tropical forest where Geoffroy's spider monkey was studied -- as a general indicator of what happened over time in each of the habitats. From Barro Colorado, the scientists knew the number of tree species that were fruiting and flowering each month during the years between 1987 and 2004. They also looked at the annual values of flower and seed production for 44 specific tree species with seeds that are spread by mammals.
To examine these factors on a regional and local scale, Wiederholt and Post used information on mean annual temperature, rainfall, and the length of the wet and dry seasons for the years between 1960 and 1990 in Venezuela, Brazil, Barro Colorado Island, and Colombiaavailable. They obtained these data from the Smithsonian Tropical Research Institute and from the Center for Climatic Research at the University of Delaware. "We expected to find a strong relationship between the large-scale climate and the population dynamics of these species," explains Wiederholt. "We also wanted to tease out which measures of vegetation-response to climatic conditions were most influential."
Some ecologists have speculated that high production of fruit during El Niño events may have been triggered by the increase in solar radiation, despite lower-than-usual rainfall. However, high productivity during an El Niño event might also use up the stored reserves of the trees, which would have difficulty recovering during the subsequent La Niña events, when weather was wet, cloudy, and cool. This mechanism would explain why the fruit-eating monkeys showed a delayed response to the El Niño events after a lag of one or two years.
Howler monkeys also showed declines with warm and dry El Niño events, but their population fall was out of sync with that of the fruit-eating species. The mechanism is not yet clear, but Wiederholt has some ideas. She notes, "Primate researchers have seen elevated adult female mortality and lowered birthrates among red howlers in drought years. Since leaf flush often occurs at the start of the wet season, a prolonged dry season might delay the availability of this resource for the howlers and perhaps cause them nutritional stress."
Warmer temperatures also may cause leaves -- the howlers' primary food -- to mature faster, which would accelerate the leaves' acquisition of toxins and other chemical defenses against monkeys. The factor that the scientists found was most influenced by changes in climate was the monthly maximum number of tree species that were fruiting. Climate changes also were highly correlated with the monthly maximum number of species that were flowering and with annual seed production. The length of the dry season also was highly correlated with annual flower production. Thus, vegetation responses to climatic conditions substantially altered the food resources available to primates, which in turn influenced the decline or rise in monkey abundance.
Global warming already has produced a rise of 0.74 degrees over the last century, and an additional increase of 1.8 to 4 degrees Celsius is anticipated over the next century. "El Niño events are expected to increase in frequency with global warming," explains Post. "This study suggests that the consequences of such intensification of ENSO could be devastating for several species of New World monkeys."
The researchers say that now, more than ever, quantitative studies that delineate the complex ecological links between climate, vegetation, and animal survival are urgently needed.
This study was funded by Penn State's Graduate Fellowship Program in a grant to Ruscena Wiederholt.CONTACTS:
Barbara K. Kennedy | EurekAlert!
Complete skin regeneration system of fish unraveled
24.04.2018 | Tokyo Institute of Technology
Scientists generate an atlas of the human genome using stem cells
24.04.2018 | The Hebrew University of Jerusalem
At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.
Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
24.04.2018 | Information Technology
24.04.2018 | Earth Sciences
24.04.2018 | Life Sciences