Posts tagged trees
The Flower Bin
Apr 24th
The Flower Bin is proud to have been serving local gardeners for 43 years. They grow most of their own plants! The ‘Bin has been helping gardeners of all ages and experience levels fill their gardens and homes with locally-grown options for any occasion.
1805 Nelson Road
Longmont, CO 80501
Phone: (303) 772-3454
Monday to Saturday: 8 a.m. to 6 p.m.
Sunday: 9 a.m. to 6 p.m.
News from The Flower Bin
Asian migrants stuck on land bridge for milleniums
Feb 27th
likely a long-term refuge for early Americans
A new study led by the University of Colorado Boulder bolsters the theory that the first Americans, who are believed to have come over from northeast Asia during the last ice age, may have been isolated on the Bering Land Bridge for thousands of years before spreading throughout the Americas.
The theory, now known as the “Beringia Standstill,” was first proposed in 1997 by two Latin American geneticists and refined in 2007 by a team led by the University of Tartu in Estonia that sampled mitrochondrial DNA from more than 600 Native Americans. The researchers found that mutations in the DNA indicated a group of their direct ancestors from Siberia was likely isolated for at least several thousand years in the region of the Bering Land Bridge, the now-submerged plain that lies between northeast Asia and Alaska once exposed by a significantly lower sea level.
CU-Boulder researcher John Hoffecker, lead author of a short paper article appearing in the Feb. 28 issue of Science magazine, said the Beringia Standstill model gained little traction outside of the genetics community after it was proposed and has been seen by some scientists outside of the field as far-fetched. But the new paper by Hoffecker and co-authors Scott Elias of Royal Holloway, University of London, and Dennis O’Rourke of the University of Utah adds credence to the Beringia Standstill idea by further linking the genetics to the paleoecological evidence.
“A number of supporting pieces have fallen in place during the last decade, including new evidence that central Beringia supported a shrub tundra region with some trees during the last glacial maximum and was characterized by surprisingly mild temperatures, given the high latitude,” said Hoffecker of CU-Boulder’s Institute of Arctic and Alpine Research. The last glacial maximum peaked roughly 21,000 years ago and was marked by the growth of vast ice sheets in North America and Europe.
While a debate rages on about when early humans first migrated into the New World, many archaeologists now believe it was sometime around 15,000 years ago after retreating glaciers opened access to coastal and interior routes into North America.
The relatively mild summer climate in Beringia at the time was caused by North Pacific circulation patterns that brought moist and relatively warm air to the region during the last glacial maximum. Geologists believe the Beringia gateway between Siberia and Alaska was more than 600 miles wide at the time.
Hoffecker and others are now theorizing that a population of hundreds or thousands of people parked itself in central Beringia for 5,000 years or more. One key to the extended occupation may have been the presence of wood in some places to use as a fuel to supplement bone, which burns hot and fast. Experiments have shown that at least some wood is necessary to make bone practical as a fuel.
Elias, a paleoecologist and also an INSTAAR affiliate, said research using fossil pollen, plant and insect material from sediment cores from the now submerged landscape show that the Bering Land Bridge tundra environment contained enough woody plants and trees like birch, willow and alder to provide a supplement to bone.
Work by Elias and others included the analysis of certain beetle species that live in very specific temperature zones, allowing them to be used as tiny thermometers. The insects indicated that temperatures there were relatively mild during last glacial maximum that ran from about 27,000 years to 20,000 years ago, only slightly cooler than temperatures in the region today.
“The climate on the land bridge and adjacent parts of Siberia and Alaska was a bit wetter than the interior regions like central Alaska and the Yukon, but not a lot warmer,” said Elias. “Our data show that woody shrubs were available on the land bridge, which would have facilitated the making of fires by the people there.”
Evidence from the 2007 study indicated a set of genetic mutations in mitochondrial DNA, which is passed down from mother to offspring, clearly accumulated after the divergence of people from their Asian parent groups in Siberia but before their dispersal throughout the Western Hemisphere, said O’Rourke. In addition, ancient DNA from human skeletal remains found at a 24,000-year-old archaeological site in southern Siberia also appears consistent with the divergence of Native American groups from their Asian forbearers by that time window, he said.
“The genetic record has been very clear for several years that the Native American genome must have arisen in an isolated population at least by 25,000 years ago, and the bulk of the migrants to the Americas really didn’t arrive south of the ice sheets until nearly 15,000 years ago,” O’Rourke said. “The paleoecological data, which I think most geneticists have not been familiar with, indicate that Beringia was not a uniform environment, and there was a shrub tundra region, or refugium, that likely provided habitats conducive to continuous human habitation.”
“From my view the genetics and paleoecology data come together nicely,” said Hoffecker, who co-authored a 2007 book with Elias titled “The Human Ecology of Beringia.” While the weakest link to the Out of Beringia theory is the lack of archaeological evidence, Hoffecker believes future research on now submerged parts of Beringia as well as lowlands in western Alaska and eastern Siberia that still remain above water may hold clues to ancient habitation by Beringia residents, who eventually moved on to be the first group to inhabit the Americas.
Hoffecker also believes that the Beringia inhabitants during the last glacial maximum could have made successful hunting forays into the uninhabited steppe-tundra region to both the east and west, where drier conditions and more grass supported a plentiful array of large grazing animals, including steppe bison, horse and mammoth.
There is now solid evidence for humans in Beringia before the last glacial maximum, as geneticists first predicted in 1997, said Hoffecker. After the maximum, there are two sets of archaeological remains dating to less than 15,000 years ago. “One represents a late migration from Asia into Alaska at that time,” he said. “The other has no obvious source outside Beringia and may represent the people who are thought to have sheltered on the land bridge during the glacial maximum.
“If we are looking for a place to put all of these people during the last glacial maximum, Beringia may be the only realistic option,” said Hoffecker.
A video news story on the research is available at http://www.colorado.edu/news.
-CU-
CU study: Some primates sleep in caves for safety
Dec 4th
The ring-tailed lemurs may be opting to sleep in caves for several reasons, said University of Colorado Boulder anthropology Associate Professor Michelle Sauther, who led the study. While the cave-sleeping behavior is likely important because it provides safety from potential predators, it also can provide the primates with access to water and nutrients, help to regulate their body temperatures during cold or hot weather and provide refuge from encroaching human activities like deforestation, she said.
“The remarkable thing about our study was that over a six-year period, the same troops of ring-tailed lemurs used the same sleeping caves on a regular, daily basis,” she said. “What we are seeing is a consistent, habitual use of caves as sleeping sites by these primates, a wonderful behavioral adaptation we had not known about before.”
A paper on the subject appeared in the November issue of the journal Madagascar Conservation and Development. Funding for the project came from Primate Conservation Inc., the International Primate Society, the American Society of Primatologists, the National Geographic Society, CU-Boulder, the University of North Dakota, Colorado College and the National Science Foundation.
Although sleeping in caves by ring-tailed lemurs — which are found only in Madagascar — has likely been going on for millennia, it is only now being recognized as a regular behavior, said Sauther. The endangered Fusui langurs, slender, long-tailed Asian monkeys roughly 2 feet tall, also have been documented sleeping in caves but as a direct result of extreme deforestation, moving from cave to cave every few days. There also have been isolated reports of South African baboons sleeping in caves.
Ring-tailed lemurs are easily identified by their characteristic, black and white ringed tails, which can be twice as long as their bodies. They weigh roughly 5 pounds with a head-body length of up to 18 inches and are highly social, congregating in groups of up to 30 individuals. Sporting fox-like snouts and slender frames, they are unusual among lemurs, spending a considerable amount of time on the ground feeding on leaves and fruit and socializing, said Sauther.
In “gallery forests” near rivers, ring-tailed lemurs regularly sleep high in the canopies of tall trees. But in “spiny forests,” most of the trees with woody stems are covered in rows of spines, making them uncomfortable as well as dangerous sleeping sites because predators can easily climb them, Sauther said. The new study documents their cave sleeping behavior in the dry spiny forest habitat adjacent to limestone cliffs.
The lemur observations were made at the 104,000-acre Tsimanampesotse National Park and the Tsinjoriake Protected Area in southwestern Madagascar between 2006 and this year. The research team used field observations and motion-detector camera traps to chart the behavior and movements of 11 different troops of ring-tailed lemurs.
One of the early clues to the cave sleeping by the lemurs was their presence on limestone cliffs adjacent to spiny forest trees or on the ground when Sauther’s research team arrived at the study sites early in the morning. “They seemed to come out of nowhere, and it was not from the trees,” she said. “We were baffled. But when we began arriving at the study sites earlier and earlier in the mornings, we observed them climbing out of the limestone caves.”
The primary predator of the lemurs is a cat-like, carnivorous mammal called a fossa native only to Madagascar that is closely related to the mongoose and may weigh up to 20 pounds. Fossil evidence shows a cougar-sized relative of the fossa that only became extinct several thousand years ago likely preyed on lemurs as well, she said.
There is evidence that some early ancestors of humans in South Africa may have used caves to protect themselves from predators, said Sauther. The remains of hominids going back several million years have been found inside or near limestone caves there, and some fossil bones have evidence of damage consistent with the bite of saber-toothed cats.
“We think cave-sleeping is something ring-tailed lemurs have been doing for a long time,” she said. “The behavior may be characteristic of a deep primate heritage that goes back millions of years.”
Co-authors of the new study included Associate Professor Frank Cuozzo of the University of North Dakota, Ibrahim Antho Youssouf Jacky, Lova Ravelohasindrazana and Jean Ravoavy of the University of Toliara in Madagascar, Krista Fish of Colorado College in Colorado Springs, Colo., and Marni LaFleur of the University of Veterinary Medicine in Vienna. Fish and LaFleur are former CU-Boulder students of Sauther.
Sauther co-directs the Beza Mahafalay Lemur Biology Project in southwestern Madagascar with Cuozzo, a former CU-Boulder doctoral student. Centered at the roughly 1,500-acre Beza Mahafalay Special Reserve, the research focuses on how climate- and human-induced change affects lemur biology, behavior and survival.
Sauther and her team were aided by field observations made by students and faculty from the University of Toliara in Madagascar. In addition, undergraduate and graduate students from CU-Boulder regularly travel to Madagascar to conduct research under Sauther, including students from CU’s Undergraduate Research Opportunities Program, which provides hands-on research and fosters student-faculty relationships.
“I never thought I would have a chance as a CU undergraduate to conduct research in an exotic place like Madagascar,” said former UROP student Anthony Massaro, who was part of a team that trapped ring-tailed lemurs, measured their physical characteristics including dentition, and released them back into the wild. “Dr. Sauther and Dr. Cuozzo mentored and guided me through the process of creating and conducting a unique research project.”
Unfortunately, habitat destruction, including deforestation, is increasing in many parts of Madagascar. In southwestern Madagascar, trees are being harvested for cattle forage, construction materials and firewood, and the mining of limestone there — used for the production of cement, fertilizer and other products — is increasing. Ring-tailed lemurs are now listed as an endangered species by the International Union for the Conservation of Nature’s Species Survival Commission.
Sauther has been conducting research on Madagascar for 25 years, beginning as a University of Washington graduate student. Today she has several CU-Boulder doctoral students working with her, including James Millette, who is studying how the tooth wear of lemurs relates to their foraging behaviors.
“Madagascar is a challenging place to conduct research,” Millette said. “Part of our job is to work with local communities, because without the support of these people there would be no lemur conservation. We consider Beza, where we have been working with the community for several decades, to be a real success story.”
A video of ring-tailed lemurs climbing into a cave is available at https://www.youtube.com/watch?v=vjWF3_SmYS0&feature=youtu.be.
-CU-