Bat faeces and biodiversity in Indonesia


This 2015 video says about itself:

Bat Man of Borneo | Expedition Raw

Braving guano, urine, and infectious diseases is all in a day’s work for bat ecologist Donald McFarlane, who descends into the depths of Borneo’s Gomantong Caves [in Malaysia] to study the bats that live there.

From James Cook University in Australia:

Holy Pleistocene Batman, the answer’s in the cave

Let’s say you wanted to solve a 20,000-year-old mystery, where would you start?

April 25, 2019

Summary: Examining a 3-meter stack of bat feces has shed light on the landscape of the ancient continent of Sundaland. The research could help explain the biodiversity of present-day Borneo, Sumatra, and Java. It could also add to our understanding of how people moved through the region.

Let’s say you wanted to solve a 20,000-year-old mystery, where would you start? Perhaps archaeology and geology come to mind. Or, you could sift through a 3-metre pile of bat faeces.

Researchers from James Cook University in Cairns, Australia, chose the bat poo in their quest to answer to a long-standing question: why is there some much biodiversity on the islands of Sumatra, Borneo and Java, when not so long ago (geologically speaking) they were all part of one vast continent?

One theory has been that the former continent (Sundaland) was dissected by a savanna corridor. “That might explain why Sumatra and Borneo each have their own species of orang-utan, even though they were linked by land for millions of years,” Dr Chris Wurster said. “The corridor would have divided the two separate rainforest refuges, as the sea does now.”

The corridor theory has been boosted by millions of insect-eating bats, which have gathered evidence about the landscape over millennia and deposited it in layers in their caves.

“Bat poo is highly informative, and especially so in the tropics, where the climate can make some of the more traditional modes of investigation less available,” Dr Wurster said.

A three-metre pile of bat faeces at Salah Cave in Borneo gave the researchers a 40,000-year-old record composed of insect skeletons.

“We can’t tell what insects the bats were eating throughout that time, because they’re in tiny fragments, but we can read the chemistry,” Dr Wurster said.

“Eating insects that have been feeding on tropical grasses results in faeces with a characteristic chemical imprint. It’s quite different from the result you’d get from eating insects that fed on tropical trees.”

According to the bat record the landscape around Saleh Cave (now featuring lush rainforest) was once dominated by tropical grasses.

“Combined with other cave studies in the region, this leads us to support the corridor theory, and also gives us some confidence as to the extent of the corridor,” Dr Wurster said.

The corridor could also shed light on human pre-history.

“A savanna corridor, which would be much more easily traversed than rainforest, might help to explain how people moved relatively quickly through this region and on to Australia and New Guinea.”

‘Savanna in equatorial Borneo during the late Pleistocene’ is published in the latest edition of Scientific Reports.

Dr Chris Wurster is a Senior Research Associate at James Cook University, specialising in stable isotope geochemistry.

Advertisements

Brazilian river dolphins communication, new study


This 2014 video says about itself:

A new species of river dolphin has been discovered by scientists working in Brazil. This is the fifth known species of its kind, and there are an estimated one thousand of the dolphins living in the Araguaia river basin.

Researchers from the Federal University of Amazonas ran genetic testing on some of the dolphins to be certain that a new species had been found. The last time a new species of river dolphin was discovered was back in 1918.

Doctor Tomas Hrbek, lead author of the study, is quoted as saying: “It is very similar to the other ones. It was something that was very unexpected, it is an area where people see them all the time, they are a large mammal, the thing is nobody really looked.” The Araguaia dolphins are smaller and reportedly have fewer teeth than the Amazon river dolphins, also called boto or pink dolphins, which are believed to be the most intelligent of the river dolphins.

From the University of Vermont in the USA:

Mysterious river dolphin helps crack the code of marine mammal communication

April 19, 2019

The Araguaian river dolphin of Brazil is something of a mystery. It was thought to be quite solitary, with little social structure that would require communication. But Laura May Collado, a biologist at the University of Vermont, and her colleagues have discovered that the dolphins can actually make hundreds of different sounds to communicate, a finding that could help uncover how communication evolved in marine mammals.

“We found that they do interact socially and are making more sounds than previously thought,” she says. “Their vocal repertoire is very diverse.”

The findings of May Collado are her colleagues were published in the journal PeerJ on April 18.

The Araguaian dolphins, also called botos, are a difficult animal to study. They are hard to find in the first place, and while the waters of the Araguaia and Tocatins rivers are clear, it is challenging to identify individuals because the dolphins are skittish and hard to approach.

Luckily, Gabriel Melo-Santos, a biologist from the University of St Andrews in Scotland and leader of the project, found a fish market in the Brazilian town of Mocajuba where the botos regularly visit to be fed by people shopping there. The clear water and regular dolphin visits provided a unique opportunity to get a close look at how the animals behave and interact, and to identify and keep track of various individuals.

The team used underwater cameras and microphones to record sounds and interactions between the dolphins at the market, and took some genetic samples. They identified 237 different types of sounds the dolphins make, but even with 20 hours of recordings the researchers don’t believe they captured the animals’ entire acoustic repertoire. The most common sounds were short, two-part calls that baby dolphins made when they were approaching their mothers.

“It’s exciting; marine dolphins like the bottlenose use signature whistles for contact, and here we have a different sound used by river dolphins for the same purpose,” says May Collado. The river dolphins also made longer calls and whistles, but these were much rarer, and the reasons for them are not yet clear. But there is some indication that whistles serve the opposite purpose than in bottlenose dolphins, with the botos using them to maintain distance rather than for group cohesion.

The acoustic characteristics of the calls are also interesting; they fall somewhere between the low-frequency calls used by baleen whales to communicate over long distances, and the high-frequency ones used by marine dolphins for short distances. May Collado speculates that the river environment may have shaped those characteristics.

“There are a lot of obstacles like flooded forests and vegetation in their habitat, so this signal could have evolved to avoid echoes from vegetation and improve the communication range of mothers and their calves,” she says.

May Collado and her colleagues next want to study whether the same diversity of communication is seen in other populations of Araguaian river dolphins that are less accustomed to humans, and compare them to their relatives elsewhere in South America. The Araguaian dolphins are closely related to two other species, the Bolivian river dolphin and Amazon river dolphin; the Araguaian dolphins were only described as a separate species in 2014, and that classification is still under debate. But there seems to be a large amount of variation in the repertoire of sounds each species makes.

The Amazon dolphins in Ecuador, studied by May Collado in 2005, are generally very quiet. “We need more information on these other species and more populations,” she says. “Why is one population chattier than others and how do these differences shape their social structure?”

May Collado says the work could help researchers gain clearer understanding of how communication evolved in marine mammals. Similar calls have been reported in pilot whales and killer whales, for example, and the similarities and differences between different species could help tease out which signals evolved first, and why.

The river dolphins are evolutionary relics, represented by just a few species around the world, and they diverged from other cetaceans much earlier than other dolphins. So these calls may have arisen first in river dolphins, then later evolved in marine dolphins into whistles and calls but in a different social context. Or was there a change in the function of the calls, with this kind of sound being used for group identity in killer whales, and individual identity in river dolphins? The calls may also have other functions in addition to identity, perhaps indicating group identity, or providing information on emotional state.

“We can’t say what the evolutionary story is yet until we get to know what sounds are produced by other river dolphins in the Amazon area, and how that relates to what we found,” she says. “We now have all these new questions to explore.”

Big prehistoric carnivore discovered in Kenyan museum


This 18 April 2019 video is called Newly Discovered Ancient Carnivore Was Bigger Than a Polar Bear.

From Ohio University in the USA:

Fossils found in museum drawer in Kenya belong to gigantic carnivore

Paleontologists say mammal was larger than a polar bear

April 18, 2019

Paleontologists at Ohio University have discovered a new species of meat-eating mammal larger than any big cat stalking the world today. Larger than a polar bear, with a skull as large as that of a rhinoceros and enormous piercing canine teeth, this massive carnivore would have been an intimidating part of the eastern African ecosystems occupied by early apes and monkeys.

In a new study published in the Journal of Vertebrate Paleontology, the researchers name Simbakubwa kutokaafrika, a gigantic carnivore known from most of its jaw, portions of its skull, and parts of its skeleton. The 22-million-year-old fossils were unearthed in Kenya decades ago as researchers canvassed the region searching for evidence of ancient apes. Specimens were placed in a drawer at the National Museums of Kenya and not given a great deal of attention until Ohio University researchers Dr. Nancy Stevens and Dr. Matthew Borths rediscovered them, recognizing their significance.

“Opening a museum drawer, we saw a row of gigantic meat-eating teeth, clearly belonging to a species new to science,” says study lead author Borths. Borths was a National Science Foundation Postdoctoral Research Fellow with Stevens in the Department of Biomedical Sciences at Ohio University when the research was conducted, and is now Curator of the Division of Fossil Primates at the Duke Lemur Center at Duke University.

Simbakubwa is Swahili for “big lion” because the animal was likely at the top of the food chain in Africa, as lions are in modern African ecosystems. Yet Simbakubwa was not closely related to big cats or any other mammalian carnivore alive today. Instead, the creature belonged to an extinct group of mammals called hyaenodonts.

Hyaenodonts were the first mammalian carnivores in Africa. For about 45 million years after the extinction of the non-avian dinosaurs, hyaenodonts were the apex predators in Africa. Then, after millions of years of near-isolation, tectonic movements of the Earth’s plates connected Africa with the northern continents, allowing floral and faunal exchange between landmasses. Around the time of Simbakubwa, the relatives of cats, hyenas, and dogs began to arrive in Africa from Eurasia.

As the relatives of cats and dogs were going south, the relatives of Simbakubwa were going north. “It’s a fascinating time in biological history,” Borths says. “Lineages that had never encountered each other begin to appear together in the fossil record.”

The species name, kutokaafrika, is Swahili for “coming from Africa” because Simbakubwa is the oldest of the gigantic hyaenodonts, suggesting this lineage of giant carnivores likely originated on the African continent and moved northward to flourish for millions of years.

Ultimately, hyaenodonts worldwide went extinct. Global ecosystems were changing between 18 and 15 million years ago as grasslands replaced forests and new mammalian lineages diversified. “We don’t know exactly what drove hyaenodonts to extinction, but ecosystems were changing quickly as the global climate became drier. The gigantic relatives of Simbakubwa were among the last hyaenodonts on the planet,” remarks Borths.

“This is a pivotal fossil, demonstrating the significance of museum collections for understanding evolutionary history,” notes Stevens, Professor in the Heritage College of Osteopathic Medicine at Ohio University and co-author of the study. “Simbakubwa is a window into a bygone era. As ecosystems shifted, a key predator disappeared, heralding Cenozoic faunal transitions that eventually led to the evolution of the modern African fauna.”

This study was funded by grants from the National Science Foundation (EAR/IF-0933619; BCS-1127164; BCS-1313679; EAR-1349825; BCS-1638796; DBI-1612062), The Leakey Foundation, National Geographic Society (CRE), Ohio University Research Council, Ohio University Heritage College of Osteopathic Medicine, SICB and The Explorers Club.

This discovery underscores both the importance of supporting innovative uses of fossil collections, as well as the importance of supporting the research and professional development of talented young postdoctoral scientists like Dr. Borths,” said Daniel Marenda, a program director at the National Science Foundation, which funded this research. “This work has the potential to help us understand how species adapt — or fail to adapt in this case — to a rapidly changing global climate.”

Horses hooves’ evolution, new research


This video is a 2017 National Geographic documentary about horse evolution.

From the University of Bristol in England:

Is one toe really better than three? How horse’ legs evolved for travel rather than speed

April 17, 2019

Palaeobiologists from the University of Bristol and Howard University (USA) have uncovered new evidence that suggests that horses’ legs have adapted over time to be optimised for endurance travel, rather than speed.

The ancestors of horses (including asses and zebras) had three toes on each foot. Because only single-toed (monodactyl) forms survive today this anatomy has been perceived as a superior evolutionary outcome, enabling horses to outrun predators.

But our interpretation of equine evolution may be biased by our own history with horses: performance at the racetrack has been less important for human history than the endurance of horses at slower speeds, and such endurance may have been the critical factor in horse evolution.

The research team combined evidence from the fossil record with existing studies on horse locomotion and propose that the adaptive significance of single-toed limbs was for trotting during roaming for food and water, rather than for galloping to avoid carnivores.

The real evolutionary ‘step forward’ in horse foot anatomy was not the loss of additional toes, but the evolution of the ‘spring foot’.

This pogo-stick type of foot anatomy evolved in the three-toed distant ancestors of modern horses, which sported an enlarged central toe but retained small ‘side toes’, which likely prevented the foot from over-extending during extreme locomotor performance.

The ‘spring foot’ enables the storage of elastic energy in the limb tendons during locomotion, and its evolution coincided with the spread of grasslands around 20 million years ago in North America (the original home of horse evolution).

The spring-footed horses radiated extensively and were as diverse during their time as antelopes in Africa today.

By around 11-million-years ago they also spread into Eurasia and Africa, where they eventually included forms larger than a modern horse. But only the lineage leading to modern horses, one amongst many, showed any tendency to reduce the number of toes.

If being single-toed was evolutionary advantageous, why did the majority of horses retain the three-toed condition for most of their evolutionary history?

Professor Christine Janis, lead author from the University of Bristol’s School of Earth Sciences (and also affiliated with Brown University, USA) said: “Early members of the single-toed horse lineage were not only losing their side toes, but the bones of the remaining central toe showed evidence of the boosting-up of the ‘spring foot’ apparatus, implying that these horses were becoming more reliant on energy-efficient locomotion.

“But at the same time these horses’ backs were becoming shorter and stiffer, contraindicative of adaptation for the back-flexing fast galloping gait. Rather, the preferred locomotion was more likely the medium-speed trot.”

The authors propose that the early single-toed horses were changing their daily foraging behaviour to roam more widely in search of food, promoting energy-saving adaptations in their feet.

The loss of the side toes may simply have been a consequence of upgrading the anatomy of the main, central toe, and with the boosted-up ligament system their original function was no longer necessary.

Single-toed horses appeared in North America around 12-million-years ago. Over the next few million years they radiated alongside three-toed horses but remained pony-sized and were neither diverse nor numerous.

But at this time the climate in northern latitudes was becoming cooler and drier. An increase in roaming behaviour would promote selection for the energy-efficient single-toed foot.

At the time, the foraging behaviour of the single-toed horses would have been one adaptive strategy among an equine diversity, much as different kinds of antelope have different modes of foraging today.

But by around five million years ago the cooling and drying trend became more intense worldwide; the former great diversity of three-toed horses had dwindled, and the direct ancestor of modern horses (early species of the genus Equus) appeared. By a million years ago all lineages of three-toed horses were extinct.

Why were single-toed horses the only equine lineage to survive to the present day? It is unlikely that competition was involved between the differently-adapted equines, as the Old World three-toed horses started their decline several million years before Equus emigrated from North America to join them 2.5 million years ago. More likely, the climatic changes of the late Cenozoic favoured the evolutionary strategy of the single-toed horses.

Professor Ray Bernor, the co-author of the paper, from Howard University’s College of Medicine, notes that the single-toed horses really just got a lucky break due to changing climates.

He added: “The three-toed horses, especially the Old World hipparions, were an incredibly successful radiation, and their skeletons showed adaptations for leaping and springing as well as running. But they evolved for a world that was warmer and wetter than that of today, and like many other large mammals did not survive to the present day.”

Single-toed horses became the dominant equines across the world in the past couple of million years, and only went extinct in the Americas at the end of the Pleistocene, around 12,000 years ago.

Professor Janis added: “However, nobody could have foreseen this eventual success ten million years ago, when single-toed horses were merely a minor lineage among equines, confined to North America.

“Their foot anatomy was ultimately important for finding food, rather than for avoiding becoming food themselves.”

Snow leopards, video


This 5 April 2019 video says about itself:

Snow Leopards 101 | Nat Geo Wild

Snow leopards are one of the world’s most elusive cats. Learn how these “mountain ghosts” are perfectly equipped to thrive in extreme, high-elevation habitats, and how they expertly hunt agile prey.

Great white sharks scared of killer whales


This video says about itself:

This Is The Biggest Great White Shark Ever Caught On Camera

Great white sharks are… big. Obviously. But a few years ago, divers met up with Deep Blue, probably the biggest great white shark ever caught on camera. So what do we know about the massive great white?

From the Monterey Bay Aquarium in the USA:

White sharks flee feeding areas when orcas present

Electronic tag data reveals white sharks do not return until following season; elephant seals benefit

April 16, 2019

Summary: New research challenges the notion that great white sharks are the most formidable predators in the ocean. The research team documented encounters between white sharks and orcas at Southeast Farallon Island off California. In every case examined by the researchers, white sharks fled the island when orcas arrived and didn’t return there until the following season. Elephant seal colonies in the Farallones also indirectly benefited from the interactions.

New research from Monterey Bay Aquarium and partner institutions published today in Nature Scientific Reports challenges the notion that great white sharks are the most formidable predators in the ocean. The study “Killer Whales Redistribute White Shark Foraging Pressure On Seals” shows how the great white hunter becomes the hunted, and the elephant seal, the common prey of sharks and orcas, emerges as the winner.

“When confronted by orcas, white sharks will immediately vacate their preferred hunting ground and will not return for up to a year, even though the orcas are only passing through,” said Dr. Salvador Jorgensen, senior research scientist at Monterey Bay Aquarium and lead author of the study.

The research team — which included Jorgensen and Monterey Bay Aquarium scientist Scot Anderson, and research partners from Stanford University, Point Blue Conservation Science and Montana State University — documented four encounters between the top predators at Southeast Farallon Island in the Greater Farallones National Marine Sanctuary, off San Francisco, California. The scientists analyzed the interactions using data from 165 white sharks tagged between 2006 and 2013, and compiled 27 years of seal, orca and shark surveys at the Farallones.

“The research in this paper combines two really robust data sources,” said Jim Tietz, co-author of the study and Farallon Program Biologist at Point Blue Conservation Science. “By supplementing the Aquarium’s new shark tagging data with Point Blue’s long-term monitoring of wildlife at the Farallon Islands National Wildlife Refuge, we were able to conclusively show how white sharks clear out of the area when the orcas show up.”

In every case examined by the researchers, white sharks fled the island when orcas arrived and didn’t return there until the following season.

Elephant seal colonies in the Farallones also indirectly benefited from the interactions. The data revealed four to seven times fewer predation events on elephant seals in the years white sharks left.

“On average we document around 40 elephant seal predation events by white sharks at Southeast Farallon Island each season,” Anderson said. “After orcas show up, we don’t see a single shark and there are no more kills.”

Each fall between September and December white sharks gather at the Farallones to hunt for young elephant seals, typically spending more than a month circling Southeast Farallon Island. Transient orcas also feed on elephant seals, but only show up occasionally at the island.

To determine when orcas and sharks co-occurred in the area, researchers compared data from the electronic shark tags with field observations of orca sightings. This made it possible to demonstrate the outcome on the rare instances when the predators encountered each other.

Electronic tags showed all white sharks began vacating the area within minutes following brief visits from orcas. Sometimes the orcas were only present for less than an hour. The tags then found the white sharks either crowded together at other elephant seal colonies farther along the coast or headed offshore.

“These are huge white sharks. Some are over 18 feet long (5.5 meters), and they usually rule the roost here,” Anderson said. “We’ve been observing some of these sharks for the past 15 to 20 years — and a few of them even longer than that.”

The study’s findings highlight the importance of interactions between top predators, which aren’t well-documented in the ocean.

“We don’t typically think about how fear and risk aversion might play a role in shaping where large predators hunt and how that influences ocean ecosystems,” Jorgensen said. “It turns out these risk effects are very strong even for large predators like white sharks — strong enough to redirect their hunting activity to less preferred but safer areas.”

The researchers drew no conclusions about whether orcas are targeting white sharks as prey or are bullying the competition for the calorie-rich elephant seals.

“I think this demonstrates how food chains are not always linear,” Jorgensen said. “So-called lateral interactions between top predators are fairly well known on land but are much harder to document in the ocean. And because this one happens so infrequently, it may take us a while longer to fully understand the dynamics.”