Ocellated lizards, new research


This 24 April 2017 video is called Watch how scales change color on real vs. simulated [ocellated] lizard skin.

It says about itself:

The scales on an ocellated lizard change color as the animal ages (more than three years of growth shown in first clip). Circles highlight four instances of color-flipping scales. Blue circles indicate a scale that switches from green to black, the green circle indicates a black to green transformation, and the light blue circle marks a scale that flip-flops from green to black to green. Researchers used a cellular automaton to simulate the adult lizard’s color-swapping scales (second clip), and re-create the labyrinthine patterns that develop on its skin.

From Science News:

The scales of the ocellated lizard are surprisingly coordinated

Lizard grows into its flashy skin using a computer-like process

By Emily Conover

6:00am, April 27, 2017

A lizard’s intricately patterned skin follows rules like those used by a simple type of computer program.

As the ocellated lizard (Timon lepidus) grows, it transforms from a drab, polka-dotted youngster to an emerald-flecked adult. Its scales first morph from white and brown to green and black. Then, as the animal ages, individual scales flip from black to green, or vice versa.

Biophysicist Michel Milinkovitch of the University of Geneva realized that the scales weren’t changing their colors by chance. “You have chains of green and chains of black, and they form this labyrinthine pattern that very clearly is not random,” he says. That intricate ornamentation, he and colleagues report April 13 in Nature, can be explained by a cellular automaton, a concept developed by mathematicians in the 1940s and ’50s to simulate diverse complex systems.

A cellular automaton is composed of a grid of colored pixels. Using a set of rules, each pixel has a chance of switching its shade, based on the colors of surrounding pixels. By comparing photos of T. lepidus at different ages, the scientists showed that its scales obey such rules.

In the adult lizard, if a black scale is surrounded by other black scales, it is more likely to switch than a black one bounded by green, the researchers found. Eventually, the lizards’ scales settle down into a mostly stable state. Black scales wind up with around three green neighbors, and green scales have around four black ones. The researchers propose that interacting pigment cells could explain the color flips.

Computer scientists use cellular automata to simulate the real world, re-creating the turbulent motions of fluids or nerve cell activity in the brain, for example. But the new study is the first time the process has been seen with the naked eye in a real-life animal.

Cuba, lizards and world’s smallest hummingbird


This video is called Cuba Playa Larga 2016.

On 13 March 2017 we went from Cayo Coco, where we had been on 12 March, to Playa Larga on the south coast of Cuba.

On Cayo Coco: white ibis (after which the island is named). Black-necked stilts. Short-billed dowitchers. Tricoloured heron. Snowy egret. Flamingos flying.

White pelicans.

At a restaurant in central Cuba: Cape May warbler.

Anolis lizard, on 13 March 2017

There were anolis lizards on the inside of the thatched roof of the restaurant.

Anolis lizard, Cuba on 13 March 2017

Cuban emerald hummingbirds were present as well. So were Cuban grassquits: they live only in Cuba and in the Bahamas.

At 17:30, we stopped at a place not far from the Zapata peninsula.

Bee hummingbird, 13 March 2017

The smallest bird in the world, the bee hummingbird, lives there. The photo shows a male.

Bee hummingbird and flowers, 13 March 2017

The bee hummingbird drank from white flowers. On the branch above it sat a Cuban pewee.

Cuban emerald hummingbird, 13 March 2017

There were also bigger relatives of the bee hummingbird: Cuban emerald hummingbirds, both males and females.

Still bigger: a Cuban oriole.

Stay tuned for more entries about Cuba on this blog!

Wall lizards get used to humans


This video from France shows a common wall lizard.

From FECYT – Spanish Foundation for Science and Technology:

Wall lizard becomes accustomed to humans and stops hiding

March 27, 2017

Summary: Habituating to predators or fleeing and hiding are tactics that vary between species. Scientists have observed that adult male common wall lizards sharing their living spaces with humans become accustomed to them and hide less when humans approach them. Yellow lizards were the most ‘daring.’

Habituating to predators or fleeing and hiding are tactics that vary between species. Scientists from two research centres in Italy and Spain have observed that adult male common wall lizards sharing their living spaces with humans become accustomed to them and hide less when humans approach them. Yellow lizards were the most “daring.”

Humans have an increasing presence in different species’ natural habitats. For this reason, scientists are investing much time in studying wild animals’ capacity to tolerate these disturbances. Lizards are an appropriate model for research into this subject, as they can be found in high densities in many environments and are relatively easy to observe in the field and handle in laboratories.

Scientists from the Eco-Ethology group of the University of Pavia (Italy) and the National Museum of Natural History (CSIC) in Spain used the lizards to analyse their reactions to attacks by human predators and the strategies they adopt, depending on the local risk level. To do this, they simulated human attacks on two populations in completely different settings: rural and urban habitats.

“The species we used in the study was the common wall lizard (Podarcis muralis). The main aim was to detect the possible influence of urbanisation on their antipredator response in terms of activity, time spent hidden in refuges after attacks and habituation to predators after repeated attacks,” Sinc was told by Jose Martín of the Spanish National Museum of Natural History and co-author of the paper, published in the journal Animal Behaviour.

The findings show that urban lizards spend less time in their refuges following simulations of predator attacks and that the[y] become habituated, as their successive hiding times decreased faster than those of the rural lizards. This detail suggests different levels of caution against potential predators. “The study has important implications for our understanding of humans’ effect on animal populations and animals’ resp[onses to them].

The explanation for this is that for prey, the majority of humans they come across represent “ineffective, dangerous predators” that rarely attack and are easily escaped from with low-intensity, low-cost antipredator responses. In this way, they save themselves always having to respond with high-intensity antipredator strategies, which can be very costly in terms of lost time and energy.

Red lizards cower when threatened

As this species displays polychromatism (there are individuals with yellow, red and white bellies), which has an important role for the species, the researchers also took individual colouration into consideration in the study.

“Independently of whether the population was rural or urban, yellow lizards gradually decreased the time they spent in their refuges compared to the other two morphs,” Martín explained. “On the other hand, red lizards progressively spent longer periods before emerging from their refuges after successive tests, suggesting growing sensitisation to potential attacks by predators.”

Previous studies had found differences between differently coloured lizards in terms of stress and haematological profiles, for instance, as well as in immune response, female reproductive strategies and males’ chemical signals.

“By using a lizard species as a model, we shed light on two key points of evolutionary ecology, concerning both antipredator response optimisation and factors enabling polymorphism to be maintained,” the researcher concluded.

A team of researchers in Italy set up two experiments for 27 ruin lizards (Podarcis sicula) collected from walls on the University of Ferrara’s campus. In the first test, the team served up two house fly larvae of varying sizes. Lizards consistently chose to scarf down bigger maggots: here.

New unique Madagascar lizard discovery


This video says about itself:

7 February 2017

In Ankarana National Park, Antsiranana Province, north Madagascar, researchers discovered a new species of fish-scale gecko: Geckolepis megalepis. To escape from predators, the gecko can lose its scales at the slightest touch. The scales grow back, scar-free, in a matter of weeks.

From Science News:

Detachable scales turn this gecko into an escape artist

Newly discovered lizard leaves predators with a mouth full of the largest scales yet

By Elizabeth Eaton

7:00am, March 17, 2017

Large, detachable scales make a newly discovered species of gecko a tough catch. When a predator grabs hold, Madagascar’s Geckolepis megalepis strips down and slips away, looking more like slimy pink Silly Putty than a rugged lizard.

All species of Geckolepis geckos have tear-off scales that regrow within a few weeks, but G. megalepis boasts the largest. Some of its scales reach nearly 6 millimeters long. Mark Scherz, a herpetologist and taxonomist at Ludwig Maximilian University of Munich, and colleagues describe the new species February 7 in PeerJ.

The hardness and density of the oversized scales may help the gecko to escape being dinner, Scherz says. Attacking animals probably get their claws or teeth stuck on the scales while G. megalepis contracts its muscles, loosening the connection between the scales and the translucent tissue underneath. The predator is left with a mouthful of armor, but no meat. “It’s almost ridiculous,” Scherz says, “how easy it is for these geckos to lose their scales.”

From BirdLife:

Some places are so rich in natural wonders, so extraordinary, so important for people, and yet so threatened, that we must pull out all the stops to save them. Madagascar, the “island continent”, with its flora and fauna so unlike any other, is one such place. Tsitongambarika, then, is even more special: forest unique even within Madagascar, with bizarre-looking Ground-rollers, local species of lemur, and species known only from this site. It is no wonder that this highly-threatened Important Bird & Biodiversity Area (IBA) – the only remaining area in the south of the country that supports significant areas of lowland rainforest, but with unprecedented rates of deforestation – has inspired a magnificent donation from Birdfair.

Birdfair, the annual British celebration of birdwatching, raised an incredible £350,000 last year at its 2016 event, and now this special funding is now going to the protection of IBAs in danger in Africa. This money will not only go towards the immediate protection of Tsitongambarika, through supporting national BirdLife Partner, Asity Madagascar, and local communities; but the future of other threatened sites in Africa will be bettered thanks to capacity building of other BirdLife Partners to advocate their protection, and to a new awards scheme.

Dinosaur age lizard discovery


This video from the USA says about itself:

3 June 2013

A team of U.S. paleontologists, led by Jason Head of the University of Nebraska-Lincoln, describes fossils of the giant lizard from Myanmar in the scientific journal Proceedings of the Royal Society B. Their analysis shows that it is one of the biggest known lizards ever to have lived on land.

At almost six feet long and weighing upwards of 60 pounds, the lizard provides new and important clues on the evolution of plant-eating reptiles and their relationship to global climate and competition with mammals.

From the University of Washington in the USA:

24 January 2017

Prized fossil find illuminates the lives of lizards in the Age of Dinosaurs

Paleontologists picking through a bounty of fossils from Montana have discovered something unexpected — a new species of lizard from the late dinosaur era, whose closest relatives roamed in faraway Asia.

This ancient lizard, which lived 75 million years ago in a dinosaur nesting site, is described from stem to stern in a paper published Jan. 25 in the Proceedings of the Royal Society B. Christened Magnuviator ovimonsensis, the new species fills in significant gaps in our understanding of how lizards evolved and spread during the dinosaur era, according to paleontologists at the University of Washington and the Burke Museum of Natural History & Culture who led the study.

“It is incredibly rare to find one complete fossil skeleton from a relatively small creature like this lizard,” said David DeMar, lead author and postdoctoral research associate in the UW biology department and the Burke Museum. “But, in fact, we had two specimens, both from the same site at Egg Mountain in Montana.”

Right out of the gate, Magnuviator is reshaping how scientists view lizards, their biodiversity and their role in complex ecosystems during this reptile’s carefree days in the Cretaceous Period 75 million years ago.

Based on analyses of the nearly complete fossil skeletons, Magnuviator was an ancient offshoot of iguanian lizards — and they’re actually the oldest, most complete iguanian fossils from the Americas. Today, iguanians include chameleons of the Old World, iguanas and anoles in the American tropics and even the infamous water-walking basilisk — or “Jesus Christ” — lizards. But based on its anatomy, Magnuviator was at best a distant relative of these modern lizard families, most of which did not arise until after the non-avian dinosaurs — and quite a few lizards and other creatures — went extinct 66 million years ago.

The team came to these conclusions after meticulous study of both Egg Mountain specimens over four years. This included a round of CT scans at Seattle Children’s Hospital to narrow down the fossil’s location within a larger section of rock and a second round at the American Museum of Natural History to digitally reconstruct the skull anatomy. The fact that both skeletons were nearly complete allowed them to determine not only that Magnuviator represented an entirely new species, but also that its closest kin weren’t other fossil lizards from the Americas. Instead, it showed striking similarities to other Cretaceous Period iguanians from Mongolia.

“These ancient lineages are not the iguanian lizards which dominate parts of the Americas today, such as anoles and horned lizards,” said DeMar. “So discoveries like Magnuviator give us a rare glimpse into the types of ‘stem’ lizards that were present before the extinction of the dinosaurs.”

But Magnuviator’s surprises don’t end with the Mongolian connection. The site of its discovery is also eye-popping.

Egg Mountain is already famous among fossil hunters. Over 30 years ago, paleontologists discovered the first fossil remains of dinosaur babies there, and it is also one of the first sites in North America where dinosaur eggs were discovered.

“We now recognize Egg Mountain as a unique site for understanding Cretaceous Period ecosystems in North America,” said senior author Greg Wilson, UW associate professor of biology and curator of paleontology at the Burke Museum. “We believe both carnivorous and herbivorous dinosaurs came to this site repeatedly to nest, and in the process of excavating this site we are learning more and more about other creatures who lived and died there.”

The team even named their new find as homage to its famous home and its close lizard relatives in Asia. Magnuviator ovimonsensis means “mighty traveler from Egg Mountain.”

Through excavations at Egg Mountain led by co-author David Varricchio at Montana State University and meticulous analysis of fossils at partner institutions like the UW and the Burke Museum, scientists are piecing together the Egg Mountain ecosystem of 75 million years ago. In those days, Egg Mountain was a semi-arid environment, with little or no water at the surface. Dinosaurs like the duck-billed hadrosaurs and the birdlike, carnivorous Troodon nested there.

Researchers have also unearthed fossilized mammals at Egg Mountain, which are being studied by Wilson’s group, as well as wasp pupae cases and pollen grains from plants adapted for dry environments. Based on the structure of Magnuviator’s teeth, as well as the eating habits of some lizards today, the researchers believe that it could have feasted on wasps at the Egg Mountain site. Though based on its relatively large size for a lizard — about 14 inches in length — Magnuviator could have also eaten something entirely different.

“Due to the significant metabolic requirements to digest plant material, only lizards above a certain body size can eat plants, and Magnuviator definitely falls within that size range,” said DeMar.

Whatever its diet, Magnuviator and its relatives in Mongolia did not make it into the modern era. DeMar and co-authors hypothesize that these stem lineages of lizards may have gone extinct along with the non-avian dinosaurs. But given the spotty record for lizards in the fossil record, it will take more Magnuviator-level discoveries to resolve this debate. And, unfortunately, part of the excitement surrounding Magnuviator is that it is a rare find.

Other co-authors are the late Jack Conrad of the New York Institute of Technology and the American Museum of Natural History and Jason Head of the University of Cambridge. The research was funded by the National Science Foundation and the American Museum of Natural History.

Draco lizards ‘flying’, video


This BBC video says about itself:

16 November 2016

Draco lizards have the amazing ability to be able to fly from tree to tree in search of food, a mate and to avoid predators.

This clip was taken from the third episode of Planet Earth II which focuses on jungles.

Green iguana feeds in Florida


This video from the USA says about itself:

Green Iguana Feeding in Florida

7 November 2016

Large wild male Green Iguana Lizard feeding on plants. They are quite stunning multicolored lizards – this one really has more blue than green on its head. Descendants of escaped or released pets – iguanas are now freely breeding in the wild and gradually spreading northward with warm winters. Small iguanas and their eggs have many predators that eat them limiting their numbers, but once they reach two feet tall and larger they have few natural enemies. They can reach six feet in length, but 3 or 4 feet long like this one is more common. This one was spotted in Palm Beach County. Hard winter freezes will generally limit their northward advances to around Palm Beach County and south of Lake Okeechobee.