Indian red-wattled lapwings and monitor lizard


This 4 October 2019 video from India says about itself:

Asian Lapwings Attempt to Scare Off a Lizard

A group of red-wattled lapwings are confronting an Indian monitor lizard that has stumbled on their nest. With little regard for their safety, they puff themselves up in the hope of scaring the predator away.

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Komodo dragons’ armour to defend themselves


This video says about itself:

The Last Kingdom of Dragons – film about Komodo by Living Zoology film studio

Komodo national park is the last place on Earth ruled by dragons. Matej and Zuzana Dolinay, authors of an unusual natural documentary, will present an insight into the life of amazing creatures living on small and remote islands in Indonesia.

From the University of Texas at Austin in the USA:

Elaborate Komodo dragon armor defends against other dragons

September 12, 2019

Just beneath their scales, Komodo dragons wear a suit of armor made of tiny bones. These bones cover the dragons from head to tail, creating a “chain mail” that protects the giant predators. However, the armor raises a question: What does the world’s largest lizard — the dominant predator in its natural habitat — need protection from?

After scanning Komodo dragon specimens with high-powered X-rays, researchers at The University of Texas at Austin think they have an answer: other Komodo dragons.

Jessica Maisano, a scientist in the UT Jackson School of Geosciences, led the research, which was published Sept.10 in the journal The Anatomical Record. Her co-authors are Christopher Bell, a professor in the Jackson School; Travis Laduc, an assistant professor in the UT College of Natural Sciences; and Diane Barber, the curator of cold-blooded animals at the Fort Worth Zoo.

The scientists came to their conclusion by using computed tomography (CT) technology to look inside and digitally reconstruct the skeletons of two deceased dragon specimens — one adult and one baby. The adult was well-equipped with armor, but it was completely absent in the baby. It’s a finding that suggests that the bony plates don’t appear until adulthood. And the only thing adult dragons need protection from is other dragons.

“Young komodo dragons spend quite a bit of time in trees, and when they’re large enough to come out of the trees, that’s when they start getting in arguments with members of their own species,” Bell said. “That would be a time when extra armor would help.”

Many groups of lizards have bones embedded in their skin called osteoderms. Scientists have known about osteoderms in Komodo dragons since at least the 1920s, when naturalist William D. Burden noted their presence as an impediment to the mass production of dragon leather. But since the skin is the first organ removed when making a skeleton, scientists do not have much information about how they are shaped or arranged inside the skin.

The researchers were able to overcome this issue by examining the dragons at UT’s High-Resolution X-ray Computed Tomography Facility, which is managed by Maisano. The lab’s CT scanners are similar to a clinical CT scanner but use higher-energy X-rays and finer detectors to reveal the interiors of specimens in great detail.

Due to size constraints of the scanner, the researchers only scanned the head of the nearly 9-foot-long adult Komodo dragon, which was donated by the Fort Worth Zoo when it passed away at 19½ years old. The San Antonio Zoo donated the 2-day-old baby specimen.

The CT scans revealed that the osteoderms in the adult Komodo dragon were unique among lizards in both their diversity of shapes and sheer coverage. Whereas the heads of other lizards examined by the researchers for comparison usually had one or two shapes of osteoderms, and sometimes large areas free of them, the Komodo had four distinct shapes and a head almost entirely encased in armor. The only areas lacking osteoderms on the head of the adult Komodo dragon were around the eyes, nostrils, mouth margins and pineal eye, a light-sensing organ on the top of the head.

“We were really blown away when we saw it,” Maisano said. “Most monitor lizards just have these vermiform (worm-shaped) osteoderms, but this guy has four very distinct morphologies, which is very unusual across lizards.”

The adult dragon that the researchers examined was among the oldest known Komodo dragons living in captivity when it died. Maisano said that the advanced age may partially explain its extreme armor; as lizards age, their bones may continue to ossify, adding more and more layers of material, until death. She said that more research on Komodo dragons of different ages can help reveal how their armor develops over time — and may help pinpoint when Komodos first start to prepare for battle with other dragons.

The National Science Foundation funded the research.

Indian lizard’s mating season video


This 3 September 2019 video says about itself:

Lizard Wows Potential Mate with Daring Feats

For the male peninsular rock agama, attracting a mate is all about demonstrating fearlessness. What better way than to perch up high on a rock, in bright-colored skin, risking being spotted by a predator?

Galápagos lava lizards, new research


This 2018 video says about itself:

Lava Lizards are the most abundant reptile in the Galápagos, and they’re among the many species native only to the region.

Video by David Pickar aboard the National Geographic Endeavour II in San Cristobal Island, Galápagos.

From ScienceDaily:

Realistic robots get under Galápagos lizards’ skin

September 4, 2019

Male lava lizards are sensitive to the timing of their opponents’ responses during contest displays, with quicker responses being perceived as more aggressive, a study in Behavioural Ecology and Sociobiology suggests.

To avoid injury from male-to-male contests, some animal species display behaviours such as color changes or sequences of movements that showcase body size and fighting ability. In lizards, one of the most recognised behaviours is the bobbing or pushup display.

Dr David Clark at Alma College, US and colleagues investigated whether lizards would react more quickly and strongly to their opponent’s bobbing display, if that display occurred immediately or with a delay following an initial challenge. The authors used remote-controlled realistic lizard robots made from hand-carved wood, high-resolution photos and latex limbs to simulate an opponent’s reaction to a wild lizards’ display.

The authors positioned lizard robots approximately 1-3m from 20 wild Galápagos Lava Lizards (Microlophus bivitattus) found on the island of San Cristóbal. After provoking an initial response by the native lizard, the researchers remotely activated the lizard robot to respond with a pre-set counter movement either immediately, or after a 30-second delay.

Dr David Clark, the corresponding author of the study said: “We had hypothesized that our Lava Lizard subjects would respond differently if the robot responded immediately to their bobbing display than if the response from the robot was delayed. The results suggest that our hypothesis was correct. We found that an immediate response by the robot stimulated the wild lizard to respond more quickly and significantly more often than when the robot’s response was delayed by 30 seconds.”

The authors suggest that the live lizards may have perceived a rapid response from their robotic contestant as more aggressive than a delayed response. This ability to assess their contestant’s level of aggression may help the lizard size up their competitor and may influence their decision to retreat or instigate a contest, helping them avoid disadvantageous injury.

Dr Clark said: “Ours is the first study to use a lizard robot that interacts with wild subjects in real-time. Previous research in this area has used either pre-recorded video playback or robots with movements set on a “loop”. The findings confirm that realistic robotic stimuli can be used to interact with animals, to communicate with them and even manipulate their behaviour. Our results further our understanding of how lava lizards communicate with each other in their natural habitat.”

The authors say that bobbing display communication in lizards could now be explored further by altering display speeds, bobbing height and the distance between the robot and subject.

Komodo dragon lizards, new research


This 11 May 2019 video says about itself:

The Raw Nature crew observe Komodo dragons hunting in the wild during a visit to Rincah Island in Indonesia. They then demonstrate the effect of the powerful Komodo venom on a piece of raw meat.

From the Gladstone Institutes in the USA:

Komodo dragon genome reveals clues about its evolution

July 29, 2019

Summary: A new study provides the first high-resolution sequence of the Komodo dragon, as well as insight into how it evolved.

The Komodo dragons are the largest lizards in the world. These predators weighing up to 200 pounds can detect their prey from up to 7.5 miles away. And although they are cold-blooded, they can ramp up their metabolism to near mammalian levels, which gives them great speed and endurance. However, scientists have understood little about how the DNA of these remarkable lizards encodes such astounding characteristics.

Now, a new study from researchers at the Gladstone Institutes, in a close collaboration with scientists at UC San Francisco (UCSF) and Zoo Atlanta, provides the first high-resolution sequence of the Komodo dragon, as well as insight into how it evolved.

“We started the project 9 years ago to look at how genomes evolve, but to do so, we needed the genome sequences first,” said Gladstone Senior Investigator Benoit Bruneau, PhD, a senior author of the study. “At the time, other groups had sequenced the turtle genome, snake and bird genomes, and the crocodile genome was in process, but the missing branch was the varanid lizards — the family to which Komodo dragons belong.”

“I went to Komodo Island years ago as a tourist, and I saw Komodo dragons in the wild there,” said Katherine Pollard, PhD, a senior investigator and the director of the Gladstone Institute of Data Science and Biotechnology, who is the other senior author of the study. “I never would have guessed then that I would one day work on their genome. We didn’t even have a human genome at that time!”

The team studied the DNA of two Komodo dragons from Zoo Atlanta named Slasher and Rinca, whose blood samples were obtained as part of their scheduled annual check-ups.

“This project was a great opportunity for us to learn more about Komodo dragons using the newest and best technologies, and then be able to contribute our findings toward the general knowledge of lizard biology,” said Joseph R. Mendelson III, PhD, a herpetologist and evolutionary vertebrate biologist, and the director of research at Zoo Atlanta.

The study, which was published in the journal Nature Ecology & Evolution and released on BioRxiv as a preprint with a data repository, provides an extremely high-quality sequence of the Komodo dragon genome, which can now be used as a reference in efforts to sequence other vertebrate genomes.

“Vertebrate genomes are big, and they contain many repetitive sequences,” explained Pollard, who is also a professor at UCSF and a Chan Zuckerberg Biohub investigator. “Most sequencing technologies only produce short stretches of sequence at a time. When those short stretches include repetitive elements, it’s impossible to know where they belong and what they connect to, making it hard to string them together.”

To get around this problem, the team took a multi-pronged approach.

“We used multiple technologies, including long-range sequencing and a physical mapping technique to do the assembly,” said Bruneau, who is also the director of the Gladstone Institute of Cardiovascular Disease and a professor in the Department of Pediatrics at UCSF. “As a result, we have a super deep, very high-quality sequence for the Komodo.”

Once the scientists had the sequence, they used computational tools to compare it to that of other reptiles and see what makes the Komodo dragon genome unique.

Specifically, they were looking for changes in the genome that helped the Komodo dragon adapt to its environment, which have undergone an evolutionary process called positive selection. A remarkable finding was that positive selection has shaped several genes involved in the function of mitochondria, the energy powerhouses of the cell that control how well heart and other muscles function.

“Our analysis showed that in Komodo dragons, many of the genes involved in how cells make and use energy had changed rapidly in ways that increase the lizard’s aerobic capacity,” said Abigail Lind, PhD, a postdoctoral researcher in Pollard’s lab and first author of the study. “These changes are likely key to the Komodo’s ability to achieve near-mammalian metabolism.”

Lizards are generally not known for their high aerobic capacity. In other words, they become exhausted quickly after physical exertions.

“However, we know from working with Komodo dragons that they’re capable of sustained aerobic activity, which could be swimming, running, or walking extremely long distances,” explained Mendelson, who is also an adjunct associate professor at the Georgia Institute of Technology. “Our study showed us that the secret is in these mitochondrial adaptations to increase their cardiac output. This gives us an understanding of how these animals are able to do what we had been observing.”

In addition, the researchers discovered that Komodo dragons, along with some other lizards, have an unexpectedly large number of genes that encode chemical sensors known as vomeronasal receptors. These receptors are part of a sophisticated sensory system that allows animals to detect hormones and pheromones.

This type of sensing is involved in a variety of activities, including kin recognition, mate choice, predator avoidance, and hunting. In the Komodo genome, the team found over 150 copies of one class of vomeronasal receptor genes. The team also found that many of these genes are unique to each individual lizard species, raising the possibility that the Komodo dragon’s vomeronasal receptors may function in Komodo-specific ways.

“It will be interesting to determine whether this explains Komodo dragons’ ability to detect prey over such large distances,” said Bruneau. “One of the exciting things about this project is that we didn’t know what to expect. This was an opportunity to look at a genome and say, ‘Tell me the story of your organism.'”

Next, Bruneau and his team are looking forward to using their findings to investigate how genes that control the formation of the vertebrate heart have changed over the course of evolution, as most reptiles have only a three-chambered heart, while mammals have four chambers.

The completed genome sequence also represents an invaluable resource for conservation biologists interested in tracking Komodo dragons to study their ecology, and for the many scientists across the world investigating vertebrate evolution.

“The significance of this study far exceeds Komodo dragons,” said Mendelson. “It gives us a framework to compare other sequenced animals and understand the genetic basis for how all their characteristics have evolved. This project also brings to the forefront the importance of preserving biodiversity, and the important role zoos can play in broad-scale research without being injurious to the animals in our care.”