Tag: History

Despite reported differences in appearance and behavior, DNA evidence finds that Namibian desert elephants share the same DNA as African savanna elephants. However, Namibian desert-dwelling elephants should be protected so they can continue to pass on their unique knowledge and survival skills to future generations.

“The ability of species such as elephants to learn and change their behavior means that genetic changes are not critical for them to adapt to a new environment,” said lead author Alfred Roca, a professor of animal sciences and member of the Carl R. Woese Institute for Genomic Biology at the University of Illinois. “The behavioral changes can allow species to expand their range to novel marginal habitats that differ sharply from the core habitat.”

Namibian desert-dwelling elephants have figured out how to prevent overheating in triple-digit temperatures by covering their bodies with sand wetted by their urine or regurgitated water from a specialized pouch beneath their tongue that holds many gallons of water. They also remember the location of scarce water and food resources across their home ranges, which are unusually large compared to those of other elephants. They play a critical role in this arid ecosystem by creating paths and digging watering holes.

Published in Ecology and Evolution, this study evaluated the nuclear DNA and mitochondrial DNA (mtDNA) of both desert-dwelling and non-desert-dwelling elephant populations throughout Namibia. Researchers found the desert-dwelling elephant DNA was not significantly different from the DNA of other savanna elephant populations in Namibia, except from those of the Caprivi Strip.

Female elephants live in tight-knit matrilineal family groups so mutations in mtDNA, which is passed from mothers to offspring, are closely tied to geographic populations. Not surprisingly, mitochondrial DNA from savanna elephants in Namibia’s Caprivi Strip — a small region analogous to Oklahoma’s panhandle — was more similar to mitochondrial DNA of elephants in Botswana and Zimbabwe, which border the Caprivi Strip.

“Our results and the historical record suggest that a high learning capacity and long distance migrations enabled Namibian elephants to shift their ranges to survive against high variability in climate and in hunting pressure,” said first author Yasuko Ishida, a research scientist in animal sciences at Illinois.

The lack of genetic differentiation (aside from the Caprivi Strip) is consistent with historical evidence of elephant movements during the Namibian War of Independence, which increased hunting pressures. Using mtDNA, the researchers identified other Namibian elephant migration patterns; for example, elephants from the Ugab River catchment shared mtDNA with elephants from the Huab River catchment, from where they are said to have migrated.

The lack of genetic differences in Namibian elephants could also be attributed to their long distance migrations; large home ranges; recent increases in population size and range; or gene flow provided by male elephants breeding with different groups of female elephants.

“Regardless, these elephants should be conserved,” said Roca. “Their knowledge of how to live in the desert is crucial to the survival of future generations of elephants in the arid habitat, and pressure from hunting and climate change may only increase in the coming decades.

“The desert elephants are also rumored to be larger, which may put them at greater risk for trophy game hunting,” he added. “Animals that live in these marginal environments are vulnerable, and their numbers do not bounce back very quickly. ”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/08/160803161607.htm  Original web page at Science Daily

Thirty years ago, the Chernobyl Nuclear Power Plant in Pripyat, Ukraine, became the site of the world’s largest nuclear accident. While humans are now scarce in the Chernobyl Exclusion Zone, continued studies–including a just-published camera study conducted by researchers from the University of Georgia’s Savannah River Ecology Laboratory–validate findings that wildlife populations are abundant at the site.

The camera study, published in the journal Frontiers in Ecology and the Environment and led by UGA’s James Beasley, is the first remote-camera scent-station survey conducted within the Chernobyl Exclusion Zone, or CEZ. The study’s results document species prevalent in the zone and support earlier findings that animal distribution is not influenced by radiation levels.

The restricted CEZ encompasses the bordering lands of Ukraine and Belarus impacted by radiation fallout from the accident, which occurred April 26, 1986.

Within the southern portion of Belarus is the Polessye, or Polesie State Radiation Ecological Reserve, with over 834 square miles of diverse landscape including forests and deserted developed lands. The levels of radiation vary significantly across this landscape.

The previous study, published in fall 2015, determined populations were thriving in the CEZ by counting animal tracks. Beasley and his research team used a more contemporary research method–remote camera stations–to substantiate previous findings.

“The earlier study shed light on the status of wildlife populations in the CEZ, but we still needed to back that up,” said Beasley, an assistant professor with UGA’s Savannah River Ecology Laboratory and the Warnell School of Forestry and Natural Resources and the senior author on the study. “For this study we deployed cameras in a systematic way across the entire Belarus section of the CEZ and captured photographic evidence–strong evidence–because these are pictures that everyone can see.”

The study was conducted over a five-week period at 94 sites using 30 cameras. A remote camera was set up on a tree or tree-like structure for seven days at each location. Each station was equipped with a fatty acid scent to attract the animals.

Sarah Webster, a graduate student at SREL and Warnell working with Beasley, set up the stations approximately 2 miles apart to prevent animals from visiting more than one station during a 24-hour period.

The team documented every species captured on the cameras and the frequency of their visits, specifically focusing on carnivores, Webster said, because of their hierarchy on the food chain.

At the top of the food chain, carnivores have an increased opportunity to receive contamination. In addition to ingesting it from prey that have foraged on the landscape, they receive it directly from the environment–through the soil, water and air.

“Carnivores are often in higher trophic levels of ecosystem food webs, so they are susceptible to bioaccumulation of contaminants,” Webster said. “Few studies in Chernobyl have investigated effects of contamination level on populations of species in high trophic levels.”

Beasley and his research team saw 14 species of mammals on the camera footage. The most frequently seen were the gray wolf, wild or Eurasian boar, red fox and raccoon dog, a canid species found in East Asia and Europe. Beasley said all of these species were sighted at stations close to or within the most highly contaminated areas.

“We didn’t find any evidence to support the idea that populations are suppressed in highly contaminated areas,” Beasley said. “What we did find was these animals were more likely to be found in areas of preferred habitat that have the things they need–food and water.”

Webster said locations were chosen to ensure habitat variance and to incorporate the diverse levels of radiation in the zone.

The study provides much needed verification, Beasley said, but further studies are needed “to determine the density of wildlife and provide quantitative survival rates.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/04/160418161400.htm  Original web page at Science Daily

A University of Queensland (UQ)-led study has discovered a new genus and two new species of extinct kangaroos which couldn’t hop, but may have been ancestral to all kangaroos and wallabies living today.

Lead author Kaylene Butler of UQ’s School of Earth Sciences said the new kangaroo species were discovered in ancient fossil deposits at the Riversleigh World Heritage Area in north-western Queensland, Australia.

“They lived around 15-23 million years ago and were the size of very small wallabies or pademelons,” she said.

“They moved on all fours, scurrying across a densely forested landscape quite different from the dry outback we see in western Queensland today.

“It also appears that our new species were direct competitors with a second group of kangaroos at Riversleigh, the even weirder ‘balbarid’ or fanged kangaroos.

“It seems likely that the fanged cousins were out-competed by our new species and their descendants.”

The new species may have been better adapted than their fanged cousins to the environmental change from rainforest to more open forest and woodland environments. They are described in the Journal of Vertebrate Paleontology.

Ms Butler worked on fossil material as part of her PhD research supervised by study co-authors former UQ Robert Day Fellow, Dr Kenny Travouillon, now of Western Australian Museum, and Dr Gilbert Price of UQ.

Riversleigh research leaders Professors Michael Archer and Suzanne Hand, of the University of New South Wales, are also study authors.

She said that by taking measurements and comparing skulls and teeth with known species, it was discovered that they were looking at both a new genus (taxonomic rank) and two new species within the genus.

She said the new genus was named Cookeroo, in honour of Dr Bernard Cooke, a distinguished Queensland Museum researcher who led much of the research program focused on the evolution of Riversleigh’s ancient kangaroos.

The two new species within the genus are Cookeroo bulwidarri, which lived about 23 million years ago, and Cookeroo hortusensis which lived 20 million to 18 million years ago.

Bulwidarri means “white” in the Aboriginal Waanyi language, and is named for White Hunter Site at the Riversleigh World Heritage Area where specimens of this species were obtained. Hortusensis is Latin for “belonging to the garden,” in reference to Neville’s Garden Site at Riversleigh where specimens of this species were found.

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/02/160222111230.htm  Original web page at Science Daily

By poring over the fossilized skulls of ancient wildebeest-like animals (Rusingoryx atopocranion) unearthed on Kenya’s Rusinga Island, researchers have discovered that the little-known hoofed mammals had a very unusual, trumpet-like nasal passage similar only to the nasal crests of lambeosaurine hadrosaur dinosaurs. The findings reported in the Cell Press journal Current Biology on February 4 offer “a spectacular example” of convergent evolution between two very distantly related taxa and across tens of millions of years, the researchers say.

“The nasal dome is a completely new structure for mammals– it doesn’t look like anything you could see in an animal that’s alive today,” says Haley O’Brien of Ohio University, Athens. “The closest example would be hadrosaur dinosaurs with half-circle shaped crests that enclose the nasal passages themselves.”

This evolutionary convergence may be explained by similarities in the way Rusingoryx and hadrosaurs lived. In fact, hadrosaurs are sometimes referred to as the “cows of the Cretaceous.”

For Tyler Faith of the University of Queensland, one of the study’s corresponding authors, it all started in 2009. He and his colleagues were working on a field program in the Lake Victoria region when other scientists directed them to a site they called Bovid Hill. The hill had been so named because of an abundance of fossil Bovidae, the group including antelopes and buffaloes, eroding from its surface.

“After several years of collecting fossils from Bovid Hill, it became very clear that most of the fossils belonged to the poorly known species Rusingoryx atopocranion, described from the same site in 1983, and that we may be dealing with an entire herd that was somehow wiped out and buried at the site,” Faith says.

The researchers also uncovered stone tools and butchered bone, raising the possibility that early modern humans had something to do with the peculiar concentration of Rusingoryx skeletons. In 2011, study co-author Kirsten Jenkins of the University of Minnesota took charge of excavations, hoping to find more complete fossils and to establish why so many skeletons had ended up in that spot. Along the way, she found several intact skulls.

“I was astonished to see that the skulls looked unlike any antelope that I had ever seen–the only thing more surprising would have been fossil zebras with horns growing from their heads!” Faith says. “The anatomy was clearly remarkable.”

Faith and O’Brien later decided to explore the anatomy further in six skulls representing Rusingoryx juveniles and adults. The similarity to hadrosaurs was immediately clear to the researchers when they opened CT scan files revealing the inner structures of those bones.

“We were expecting the inside of the dome to have something closer to normal mammalian anatomy, but once we took a look at the CT scans, we were pretty shocked,” O’Brien says.

At first, the researchers thought the hollow nasal dome might have had something to do with thermoregulation. Now, based on their anatomical investigations together with acoustical modeling, they think the trumpet-like nasal tube may have allowed Rusingoryx to deepen its normal vocal calls. In fact, their calculations suggest that the animals might have been able to call at levels very close to infrasound, such that other animals may not have been able to hear individuals in the herd calling back and forth to each other.

Both Rusingoryx and hadrosaur dinosaurs are thought to have been highly social, O’Brien explains. They might have communicated with each other across fairly large distances.

“Vocalizations can alert predators, and moving their calls into a new frequency could have made communication safer,” she says. “On top of this, we know that both Rusingoryx and hadrosaurs were consummate herbivores, each having their own highly specialized teeth. Their respective, remarkable dental specializations may have initiated changes in the lower jaw and cheek bones that ultimately led to the type of modification we see in the derived, crest-bearing forms.”

The researchers say they will continue to explore the developmental shifts required to produce the animals’ bizarre morphology. They’d also like to understand what ultimately led the once-thriving Rusingoryx to disappear.

http://www.sciencedaily.com/   Science Daily

http://www.sciencedaily.com/releases/2016/02/160204150559.htm  Original web page at Science Daily

The cheetah (Acinonyx jubatus) is now at home on the African plains, but it started a migration 100, 000 years ago from North America towards its current habitat. The research, published in the open access journal Genome Biology, found that the migration from North America was costly for the species, triggering the first major reduction in their gene pool.

The modern African cheetah is found across eastern and southern Africa, but it is highly endangered because of their small free ranging population and inbreeding. Researchers from St. Petersburg State University, Russia, in collaboration with BGI, China and CCF, Namibia, sequenced the genome from a male Namibian cheetah, called ‘Chewbaaka’, and six other wild cheetahs from Tanzania and Namibia. This gave further insight into the species evolutionary history and the breadth of genome impoverishment, which elevates juvenile mortality, causes extreme abnormalities in sperm development and increases vulnerability to infectious disease outbreaks.

A total of 18 cheetah genes showed damaging mutations and one gene in particular, AKAP4, showed a large number of mutations, which could harm sperm development and may explain why cheetah have a large proportion of defective sperm, and hence their low reproductive success.

The cheetah is descended from a relative of American pumas and their fossil record extends across the Americas, Europe and Asia. The species has suffered two population bottlenecks — an event whereby the population is rapidly reduced due to environmental factors.

The first of these took place 100, 000 years ago, around the late Pleistocene — a geological period shaped by repeated glaciations, when cheetahs started to move towards Asia across the Beringian landbridge and then travelled south to Africa. This migration was punctuated with dwindling populations and limited gene flow due to the individuals’ own vast territory boundaries, measuring 300-800 square miles, thereby increasing incestuous mating.

The second bottleneck around 10- 12, 000 years ago, further reduced numbers, leading to further loss of endemic variability observed in modern cheetahs. This is because cheetahs disappeared from North America, when the last glacial retreat caused an abrupt extinction resulting in the loss of many large mammals, including cheetahs and pumas, from North America.

Cheetahs accept skin grafts from unrelated cheetahs as if they were clones. The genome analysis suggests that this is partly due to the loss of a few immune related genes and dramatic loss of diversity in the cheetahs’ flagella genes. The variation is so limited that it is far below that observed in inbred dogs and cats. Tests carried out by the researchers show that the cheetah has lost 90-99% of the genetic variation typically seen in outbred mammals.

The researchers conclude that this latest insight into the history and adaptation of the endangered cheetah should be useful in efforts to sustain and increase cheetah population numbers in their present and former range habitats.

http://www.sciencedaily.com/ Science Daily

http://www.sciencedaily.com/releases/2015/12/151208204222.htm  Original web page at Science Daily

A distant relative of today’s giraffes was a bit of an odd creature: It was about the size of a bull moose, but it had a long neck that could stretch both up to eat tree leaves and down to eat grass. That’s the conclusion of the first comprehensive analysis of a complete set of fossilized neck bones from the animal, known as Samotherium major. Samotherium, which lived in the open woodlands of Eurasia about 7 million years ago, had a neck about 1 meter long—about half the length of that of today’s giraffes. (And like the vast majority of mammals, from tiny mice to towering giraffes, it had seven neck vertebrae.) Some scientists have long presumed today’s giraffe (Giraffa camelopardalis), which includes a handful of subspecies scattered throughout sub-Saharan Africa, evolved from an animal that looked like its close cousin the okapi (Okapia johnstoni), which lives in the tropical forests of central Africa. The team’s analyses of bones from all three animals bolster that notion—and not just because the neck bones are of a length between the giraffe’s and the okapi’s. For example, ridges and other features that are prominent on the okapi’s neck bones and missing entirely on the giraffe’s are typically present but smaller on Samotherium’s, the researchers report online today in Royal Society Open Science.

Science| DOI: 10.1126/science.aad7483

http://www.sciencemag.org/  Science Magazine

http://news.sciencemag.org/evolution/2015/11/odd-creature-was-ancient-ancestor-today-s-giraffes  Original web page at Science Magazine

During upheaval in Libya in 2013, a window of opportunity opened for scientists from the University of Kansas to perform research at the Zallah Oasis, a promising site for unearthing fossils from the Oligocene period, roughly 30 million years ago.

From that work, the KU-led team last week published a description of a previously unknown anthropoid primate — a forerunner of today’s monkeys, apes and humans — in the Journal of Human Evolution. They’ve dubbed their new find Apidium zuetina. Significantly, it’s the first example of Apidium to be found outside of Egypt.

“Apidium is interesting because it was the first early anthropoid primate ever to be found and described, in 1908,” said K. Christopher Beard, Distinguished Foundation Professor of Ecology and Evolutionary Biology and senior curator with KU’s Biodiversity Institute, who headed the research. “The oldest known Apidium fossils are about 31 million years old, while the youngest are 29 million. Before our discovery in Libya, only three species of Apidium were ever recovered in Egypt. People had come up with the idea that these primates had evolved locally in Egypt.

Beard said evidence that Apidium had dispersed across North Africa was the key facet of the find. He believes shifting climatic and environmental conditions shaped the distribution of species of Apidium, which affected their evolution.

“We’ve found evidence that climate change — not warming, but cooling and drying — across the Eocene-Oligocene boundary probably is the root cause in kicking anthropoid evolution into overdrive,” he said. “All of these anthropoids, which were our distant relatives, were living up in the trees — none of them were coming down. When the world became cooler and dryer in this period, what was previously a continuous belt of forest became more fragmented. This created barriers to gene flow and movement of animals from one part of forest to what used to be adjacent forest.” With a forest broken up, there was an inhibition of gene flow that through time resulted in speciation, or the creation of new species, according to the KU researcher.

“Animals that are sequestered become different species over millions of years,” Beard said. “As the climate oscillates again, you’ve got different species of Apidium. As forests expand and contract, now you’ve got competition between species of Apidium that have never seen each other before. One species outcompetes the other, the other goes extinct, and we think that’s what we’re picking up with this Libyan Apidium, which is related to the youngest and largest species of Apidium known from Egypt.”

Beard said that Apidium zuetina would have been physically similar to modern-day squirrel monkeys from South America, but with smaller brains, and would have dined on fruits, nuts and seeds.

“We know that Apidium was a very active arboreal monkey, a really good leaper,” he said. We know they actually had fused lower-leg bones just above the ankle joint. That’s really unusual for anthropoid primates, and the only reason for it to happen is because you like to jump a lot, as it stabilized the join between those bones and the ankle.” The team identified Apidium zuetina through detailed analysis of its teeth.

“All of the fossils we have so far are just teeth, not even jaw bones — but fortunately, the teeth of these anthropoids are so distinct and diagnostic that they function like fingerprints at a crime scene,” Beard said. “Studying details of cusps and crests on teeth, we can determine evolutionary relationships. It might sound like thin evidence, but I suspect even with whole skeletons we’d still be focused on teeth to determine relationships. This is because teeth evolve rapidly in response to shifting diets, while an animal’s skull and skeleton typically evolves more slowly. Fortunately for paleontologists, teeth are well-documented in the fossil record because tooth enamel is the hardest part of a mammal body, durable and easy to fossilize.” Yet, the researchers chose to name Apidium zuetina not after any of its physical characteristics, but after the Zuetina Oil Company that made the dangerous Libyan fieldwork possible.

http://www.sciencedaily.com/  Science Daily

http://www.sciencedaily.com/releases/2015/11/151123203116.htm  Original web page at Science Daily

As grasses grew more common in Africa, most major mammal groups tried grazing on them at times during the past 4 million years, but some of the animals went extinct or switched back to browsing on trees and shrubs, according to a study led by the University of Utah

“It’s as if in a city, there was a whole new genre of restaurant to try,” says geochemist Thure Cerling, first and senior author of the study published by the journal Proceedings of the National Academy of Sciences. “This is a record of how different mammals responded. And almost all of the mammals did an experiment in eating this new resource: grass.”

The experiment peaked about 2 million years ago, says Cerling, a distinguished professor of geology and geophysics. The only major group that still mostly grazes grass is the bovids: cattle, buffalo, sheep, wildebeest, hartebeest and some antelopes such as oryx and waterbucks.

The study also revealed that the present isn’t necessarily the key to the past in terms of what animals eat. Today, elephants and spiral-horned antelope (elands, kudus and bushbuck) browse on trees and shrubs, but the study showed that 2 million years ago, African elephants grazed on grass and the antelopes had mixed diets with a lot of grass. Asian elephants, which ate grass and were abundant in Africa 2 million years ago, went extinct in Africa but survive in Asia, where they graze but also browse trees and shrubs.

“That the diet of some of these animals is different from that of the present was a surprise, and shows the importance of challenging one’s assumptions when making ecological reconstructions,” says study co-author and geologist Frank Brown, dean of the University of Utah’s College of Mines and Earth Sciences.

Overall, Cerling and colleagues wrote that the assemblages of grazing, browsing and mixed-diet animals during the past 4 million years “are different from any modern ecosystem in East or Central Africa.”

They found the Turkana Basin of Kenya and Ethiopia had a much greater diversity of mixed feeders — they browsed and grazed — from 4.1 million to 2.35 million years ago. From 2.35 million to 1 million years ago, there were many more grazers than there are today. In the past 1 million years, many grass grazers either switched to browsing trees and shrubs or went extinct, leaving mostly bovids as grazers today.

In a study spanning 30 years of field work by Cerling into how grasses and the animals that eat them evolved together, he and other scientists analyzed:

— Hair keratin, tooth enamel or bone collagen from 1,800 animals of more than 50 modern herbivore species in East and Central Africa. Samples came from museum collections or from animals killed previously in 30 national parks and reserves.

— Tooth enamel from more than 900 fossil herbivores that lived 4.1 million to 1 million years ago in the Turkana Basin.

They measured the samples’ ratios of uncommon carbon-13 to common carbon-12. The ratios reveal if the animals browsed primarily on plants that use C3 photosynthesis (trees, shrubs, forbs and herbs), grazed mainly on C4 photosynthesis plants (dry-season or tropical grasses and sedges) or ate a mixed diet.

Low carbon dioxide levels in the atmosphere are believed responsible for a global expansion of tropical grasslands between 10 million and 5 million years ago. C4 photosynthesis used by tropical grasses is more efficient in hot climates, giving them an advantage over trees and shrubs.

“Over the past 10 million years, grasses went from perhaps 1 percent of productivity of the tropical landscape to 50 percent today,” Cerling says. “All the large mammal groups tried experiments in eating grasses, and a lot of those experiments didn’t work in the long run,” he says. “Animals became extinct or they switched to other diets. There was even a grazing giraffe, but that became extinct. There were three major lineages of pigs that were grazers, and only one has survived: the warthog.”

Other grazers that became extinct included a three-toed horse and the Asian elephant, which survives in Asia but went extinct in Africa 1 million years ago. Grazers that switched to browsing included forest hogs and African elephants. Browsers in the past that still browse at least 75 percent trees and shrubs today include most giraffes, black rhinos, tiny antelope and forest antelope. One-toed horses, warthogs, zebras, white rhinos and bovids — cattle, buffalo, goats, wildebeest, hartebeest and antelopes like waterbuck and oryx — stuck with grass.

“The successful grazers appear to be the bovids,” Cerling says, although even some bovids — gazelles and elands — once were mixed grazers-browsers, but today have returned to mostly browsing on trees and shrubs. Impalas, which also are bovids, shifted from mostly grazing in the past to both grazing and browsing today.

Modern herbivores with mixed browsing-grazing diets include hippos and impalas. Why did the grass craze fade? Why did some animals keep eating grass while others stopped or went extinct? “Perhaps they were much more efficient at eating grass and outcompeted some of the other animals,” Cerling says. For example, perhaps African elephants switched to browsing when they could no longer grab grass cut too short by grazers.

“It looks like there is as much grass available now as anytime in the past,” Cerling says. “It could be that the quality of grass varies enormously between the dry season and the wet season.” He also notes that during the past 1 million years, “we have been going through strong cycles with and without glaciers, and much bigger changes in atmospheric carbon dioxide.” Grasses using C4 photosynthesis not only have an advantage in hot weather, but also during glacial periods when carbon dioxide levels were low.

But there are no fossils of grasses for the past 10 million years, which makes it difficult to unveil the evolution of grasses, and whether they changed in digestibility, palatability, toxin levels and nutrient content, Cerling says.

In a 2013 study, Cerling found that early human relatives who turned to grazing, such as Paranthropus boisei, went extinct. Modern humans eat more grass than ever before — but not by grazing. Instead, we eat the meat of animals fed grass and C4 grains, as well as cultivated C4 plants such as corn and sorghum.

http://www.sciencedaily.com/  Science Daily

http://www.sciencedaily.com/releases/2015/08/150803154848.htm  Original web page at Science Daily