How Cayman Islands lizards adapt


This December 2018 video says about itself:

The Lizard’s Tale 101: Meet the Anoles

Anoles are small lizards with an abundance of charm. There are over 400 species of anoles, scattered all over the American and Caribbean tropics: from remote rainforests in the Bahamas, to busy cities on the mainland. In recent years, anoles have come to be viewed as a great model organism for understanding key evolutionary principles. They’ve helped scientists tackle many of the big questions in biology: from the links between ecology and evolution, to the effects of physiology and behaviour. The results are nothing short of eye-opening.

From the University of Plymouth in England:

Biological changes among invasive species

April 8, 2019

A remote island in the Caribbean could offer clues as to how invasive species are able to colonise new territories and then thrive in them, a new study suggests.

Scientists from the University of Plymouth have recently completed extensive research into a lizard population on the Cayman Islands.

Up until the mid-1980s, there had never been a recorded sighting of the Maynard’s Anole (Anolis maynardi) on Cayman Brac island despite it being less than 10km from its native territory, Little Cayman.

However, since the species was first discovered on Cayman Brac in 1987 — in what is thought to have been a human-assisted colonisation — its population has spread right across the 39km² island.

For this study, recent graduate Vaughn Bodden and Lecturer in Conservation Biology Dr Robert Puschendorf conducted a detailed analysis of the invasive species.

They wanted to assess whether individuals at the forefront of the invasion have developed distinct biological traits that are advantageous for dispersal, and compared their findings to animals in the area of first introduction and the native population on Little Cayman.

They discovered the Cayman Brac population has diverged morphologically from the native population, and within the invasive range there was trend of increasing forelimb length from the core to range edge areas. This ran contrary to the expected findings that longer hindlimbs would be the trait selected as a dispersal-related phenotype.

They also showed that the introduced population had lower levels of parasite prevalence, and that both males and females were of significantly higher body condition than the native population.

Writing in the Journal of Zoology, they say the results are a perfect example of how a species can colonise a new territory, and the biological adaptations it can make in order to do so.

Vaughn, who graduated with a First from the BSc (Hons) Conservation Biology programme in 2018, said: “There has been a history of lizard studies indicating that longer hindlimbs are an important factor affecting movement ability, so to not find longer hind limbed animals on the range edge was a surprise. For parasites, we found a clear decreasing trend in prevalence within the invasive population from the area of first introduction to the range edge, indicating that the parasites lag behind the host during periods of range expansion. We think our findings add to the growing body of literature that demonstrates the complex dynamics of species’ invasions. The results highlight that the animals on the range edge of an invasion are likely to be experiencing different ecological selection pressures that can result in changes in behaviour, morphology, and health for the animals.”

Dr Puschendorf has spent several years researching the consequences of emerging infectious diseases and climate change on biodiversity, with a particular focus on Central America. He added: “Biological invasions are an important conservation threat across the world. However, every invasion needs to be carefully investigated to identify impacts to native eco-systems and identify potential mitigation strategies. In this instance there is likely to be limited overlap with, and therefore a limited threat to, the endemic anole population — the Cayman Brac Anole (Anolis luteosignifer) — because one inhabit the crowns of trees while the other is found closer to the ground. This in some ways highlights the challenges biodiversity managers face when managing species invasions with limited resources, and emphasises the need for greater collaboration among scientific and policy communities.”

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Lizards, egg-laying and live-bearing


This 11 March 2019 video says about itself:

The Three Toed Skink (Saiphos equalis) is a beautiful burrowing lizard from the east coast of Australia! This species has some special adaptations I highlight in this video along with showing some awesome natural colour variation! Its calm nature, beautiful appearance and rarity in the reptile hobby makes it a perfect lizard to showcase here in the first episode of Species Special!

Special thanks to the Macquarie University Lizard Lab.

From the University of Sydney in Australia:

Biologists observe a three-toed skink lay eggs and give birth to a live baby

April 2, 2019

In a world first, researchers at the University of Sydney have observed a normally live-bearing Australian lizard lay three eggs and then weeks later, give birth to a live baby from the same pregnancy. This is the first time such an event has been documented in a single litter of vertebrate babies.

The three-toed skink (Saiphos equalis) is one of only a handful of rare “bimodally reproductive” species, in which some individuals lay eggs and others give birth to live babies. But up until now, no vertebrate has ever been observed to do both in one litter.

“It is a very unusual discovery”, said Dr Camilla Whittington, from the School of Life and Environmental Sciences and Sydney School of Veterinary Science at the University of Sydney.

The three-toed skink is native to the east coast of Australia. In the northern highlands of New South Wales the animals normally give birth to live young, but those living in and around Sydney lay eggs.

“We were studying the genetics of these skinks when we noticed one of the live-bearing females lay three eggs,” Dr Whittington said. “Several weeks later she gave birth to another baby. Seeing that baby was a very exciting moment!”

The observation will be published in Biology Letters this week, along with advanced microscopy of the egg-coverings.

There are at least 150 evolutionary transitions from egg-laying to live-bearing in vertebrates said Dr Whittington, who led the study alongside Dr Melanie Laird, a postdoctoral researcher at the University of Otago, and Emeritus Professor Mike Thompson.

“The earliest vertebrates were egg-layers, but over thousands of years, developing embryos in some species were held inside the body for longer, until some animals began to give live birth. People mostly think about humans and other mammals giving birth. But there are many species of reptile that give birth, too.”

Dr Whittington said that the unusual observation of both egg laying and live birth in a single litter shows that the three-toed skink is an ideal model for understanding pregnancy. “It makes Australia one of the best places in the world to study the evolution of live birth, because we can watch evolution in action,” she said.

“Put in the context of evolutionary biology, being able to switch between laying eggs and giving live birth could allow animals to hedge their bets according to environmental conditions,” Dr Whittington said.

This observation helps make the three-toed skink, which looks like a baby snake with tiny legs, one of the “weirdest lizards in the world”, she said.

Further research into this small lizard, which seems to occupy a grey area between live birth and egg-laying, will help determine how and why species make major reproductive leaps.

Basilisk, squirrel at Panama bird feeder


This video says about itself:

Common Basilisk And
Red-tailed Squirrel Meet On The Feeder – April 2, 2019

An uneasy interaction between a female Common Basilisk and a Red-tailed Squirrel as they attempt to share the bounty of fruit on the feeder.

Watch LIVE 24/7 with highlights and viewing resources at http://allaboutbirds.org/panamafeeders

The Panama Fruit Feeder Cam is a collaboration between the Cornell Lab of Ornithology, the Canopy Family, and explore.org.

Dominican Republic lizards, climate change and deforestation


This November 2017 video says about itself:

Lizard battle in Dominican Republic

Epic fight of two male lizards; in the end the loser flees like a bullet!

From the University of Toronto in Canada:

Elevation matters when it comes to climate change, deforestation and species survival

February 25, 2019

Summary: A study examining the impact of deforestation on lizard communities in the Dominican Republic demonstrates differing outcomes at different elevations. In the lowlands, deforestation reduces the number of individuals, but not which species occur in an area. In the highlands, it’s the opposite. When the forest is cut down at higher elevations, the newly created pastures become filled with species found in the warmer lowlands. But locally adapted mountain lizards cannot survive as temperature rises.

University of Toronto student George Sandler was shocked to see the rainforest floor suddenly come to life around him, as if in a scene from an Indiana Jones movie.

“The forest floor started rustling around me,” says Sandler, “as dozens of crabs emerged from holes and crevices. Some were huge, the size of dinner plates. I even spotted a hermit crab climbing up a tree, lugging its heavy shell along with it.”

But Sandler wasn’t in the field to study crabs. He was in the Dominican Republic to take a census of the region’s Anolis lizard species for a study on the effects of deforestation being conducted by researchers Luke Mahler, Luke Frishkoff and collaborators. In the Caribbean nation, deforestation is the main form of natural habitat loss as residents cut down rainforest in order to produce charcoal, as well as create pastures for livestock and farmland for crops.

It is no surprise that deforestation has a profound effect on biodiversity; scientists have been studying this problem around the globe for decades. What is surprising is the difficulty they still face in making detailed predictions about which species survive, especially in relation to other factors such as climate change and natural local conditions.

Now, using the data collected in the census, the research team has discovered details about how Anolis lizards are being affected by the loss of their habitat.

“When it comes to predicting the effects of deforestation,” says Mahler, “elevation matters.”

Mahler is an assistant professor in the Department of Ecology & Evolutionary Biology (EEB) in the Faculty of Arts & Science at the University of Toronto. Frishkoff led the research while he was a postdoctoral fellow in Mahler’s lab at U of T and is lead author of the paper describing their findings, published today in Nature Ecology & Evolution; he is currently an assistant professor at the University of Texas at Arlington. Sandler and researchers from the National Museum of Natural History in Santo Domingo were also co-authors.

Mahler and Frishkoff analyzed populations of lizards in both lowland and highland regions affected by deforestation. Generally, the lowlands are warmer than the highlands due to altitude; also, forest canopy blocks direct sunlight, making forests at any altitude cooler than their immediate surroundings.

“It turns out that deforestation changes lizard communities in fundamentally different ways in the lowlands as compared to the highlands,” says Mahler. “In the lowlands, deforestation reduces the number of individuals, but not which species occur in an area. In the highlands, it’s the opposite.”

“When the forest is cut down at higher elevations,” says Frishkoff, “the newly created high elevation pastures become filled with species we saw down in the warmer lowlands. But, the locally adapted mountain lizards cannot survive.”

The invasion into the highlands by lowland-dwelling lizards was made possible by a combination of human activity and natural factors; i.e. deforestation and elevation respectively. Thanks to the altitude, the temperature of deforested fields in the highlands was comparable to the temperature of forested lowlands.

As it is in many regions around the world, the problem of deforestation in the Dominican Republic is dire. In 2016, Mahler announced the discovery of a previously unknown chameleon-like Anolis lizard on the island of Hispaniola. In the paper describing the discovery, Mahler and his co-authors recommended that the new species, dubbed Anolis landestoyi, be immediately classified as critically endangered because the lizard was threatened by illegal clear-cutting in the region.

Unlike the crabs that crowded around Sandler in the rainforest, the lizards were more elusive and difficult to survey. In order to obtain accurate counts, the students employed a technique known as mark-resight.

“We hiked out to our designated plots,” says Sandler, who was an undergraduate student while conducting the field work and is currently an EEB graduate student at U of T. “Then we walked around looking for lizards. We carried a paint spray gun filled with a non-toxic, water soluble paint — a different colour for each of the six observation periods. If we saw a lizard we would note the species, if it had any paint on it already, and the colour of the paint. Then we would spray the lizard with the paint gun we were carrying, a task that was a little tricky with some of the more skittish species!”

Paint on a lizard indicated that it had already been counted; and the number of unpainted lizards that were observed during each period allowed the researchers to calculate how many lizards were going uncounted.

“It’s not your typical summer job,” says Mahler. “Each survey is essentially a game in which you try to find all the lizards in an area and zap them with paint. It’s a messy affair, but we get great data from it.”

“Our results help us better understand the likely consequences of climate change and how it will interact with human land-use,” says Frishkoff.

For lowland forest Anolis lizards, deforestation just means a decline in abundance or relocating to the highlands. But for highland species, the situation is more critical. Unlike their lowland cousins, they have reached high ground already and in the face of deforestation have nowhere to go — a situation facing more and more species around the world.

“Our data suggest that while many lowland Anolis species might not be seriously affected by deforestation and the gradual warming brought about by climate change,” says Frishkoff, “the opposite is true for the unique mountain lizard species which do not tolerate land-use change well, and which are already on the top of the island.

“Land-use and climate change are a double whammy for these species. If we cut down the mountain forests these lizards have nowhere left to go. Gradual warming might push species up slope, but when you’re already at the top of the mountain, you can’t move any higher.”

Gecko lizards can walk on water


This video says about itself:

Geckos can run across water

Geckos (Hemidactylus platyurus) have the ability to exceed the speed limits of conventional surface swimming, running across water at up to almost a meter a second using a unique mix of surface tension and slapping.

Credits: UC Berkeley/Roxanne Makasdjian/Stephen McNally/Pauline Jennings, Jasmine A. Nirody, Judy Jinn, Thomas Libby, Timothy J. Lee, Ardian Jusufi, David L. Hu, Robert J. Full.

Music: Horses to Water by Topher Mohr and Alex Elena courtesy of YouTube Audio Library

From the University of California – Berkeley in the USA:

Acrobatic geckos, highly maneuverable on land and in the air, can also race on water

Geckos combine surface tension with foot slapping to stay above water surface

December 6, 2018

Summary: Asian geckos were observed running over water at nearly a meter per second, as fast as on land. Lab experiments show how. They get support from surface tension but also slap the water rapidly with their feet. They also semi-plane over the surface and use their tail for stabilization and propulsion. They thus sit between insects, which use only surface tension, and larger animals, which run upright via foot slapping alone.

Geckos are renowned for their acrobatic feats on land and in the air, but a new discovery that they can also run on water puts them in the superhero category, says a University of California, Berkeley, biologist.

“They can run up a wall at a meter per second, they can glide, they can right themselves in midair with a twist of their tail and rapidly invert under a leaf running at full speed. And now they can run at a meter per second over water. Nothing else can do that; geckos are superheroes,” said Robert Full, a UC Berkeley professor of integrative biology.

Full is the senior author of a paper that will appear this week in the journal Current Biology describing four separate strategies that geckos use to skitter across the surface of water. First author Jasmine Nirody, a biophysicist at the University of Oxford and Rockefeller University, conducted much of the research with Judy Jinn, both as Ph.D. students at Berkeley.

According to Full, who discovered many of the unique maneuvers and strategies geckos employ, including how their toe hairs help them climb smooth vertical surfaces and hang from the ceiling, the findings could help improve the design of robots that run on water.

Nirody first became intrigued by geckos’ water-running behavior after co-author Ardian Jusufi, now a biophysicist at Max Planck Institute for Intelligent Systems and another former UC Berkeley Ph.D. student, noticed that geckos in the forests of southeast Asia could skitter across puddles to escape predators.

In fact, they are able to run at nearly a meter, or three feet, per second over water and easily transition to speeding across solid ground or climbing up a vertical surface. Geckos sprinting on the water’s surface exceed the absolute swimming speeds of many larger, aquatic specialists including ducks, minks, muskrats, marine iguanas and juvenile alligators, and are faster in relative speed than any recorded surface swimmer, other than whirligig beetles.

How, she wondered, do they do that?

Smaller animals like insects — spiders, beetles and water striders, for example — are light enough to be kept afloat by surface tension, which allows them to easily glide across the surface. Larger animals, such as swans during takeoff or the basilisk lizard, and even dolphins rising up on their tails, rapidly slap and stroke the water to keep above the waves.

“Bigger animals can’t use surface tension, so they end up pushing and slapping the surface, which produces a force if you do it hard enough,” Full said.

But the gecko is of intermediate size: at about 6 grams (one-fifth of an ounce, or the weight of a sheet of paper), they are too large to float above the surface, but too light to keep their bodies above water by slapping forces only.

“The gecko’s size places them in an intermediate regime, a middle ground,” Nirody said. “They can’t generate enough force to run along the surface without sinking, so the fact they can race across water is really surprising.”

In experiments with flat-tailed house geckos (Hemidactylus platyurus), common in south and southeast Asia, she discovered that they actually use at least two and perhaps four distinct strategies to run atop the water surface.

Surface tension is essential, she found, because when she applied a surfactant or soap to eliminate surface tension, the geckos were much less efficient: their speed dropped by half.

Even without surface tension, however, they can move using slapping, paddling movements with their four legs like larger animals. Leg slapping created air pockets that helped keep their bodies from being completely submerged, allowing them to trot across the water in much the same way they run on land.

But they also seem to use their smooth, water-repellent skin to plane across the surface, similar to hydroplaning but referred to as semi-planing, a technique used by muskrats.

Finally, they also use their tail to swish the water like an alligator, providing propulsion as well as lift and stabilization.

“All are important to some extent, and geckos are unique in combining all these,” Full said.

“Even knowing the extensive list of locomotive capabilities that geckos have in their arsenal, we were still very surprised at the speed at which they could dart across the water’s surface,” Nirody said. “The way that they combine several modalities to perform this feat is really remarkable.”

In the lab, she and her colleagues built a long water tank, placed the geckos on a plank and startled them by touching their tails. Using high-speed video, they were able to closely study the geckos’ techniques and estimate the forces involved.

This research was funded by the National Science Foundation and the Swiss National Science Foundation. Other co-authors of the paper are Thomas Libby and Timothy Lee of UC Berkeley and David Hu from Georgia Tech.

Australian lizards and parasites, new study


This 2017 video says about itself:

Australian Common Garden Skink or Pale-Flecked Garden Sunskink

From the University of Colorado at Boulder in the USA:

Forest fragmentation disrupts parasite infection in Australian lizards

November 29, 2018

In a study with implications for biodiversity and the spread of infectious diseases, CU Boulder ecologists have demonstrated that deforestation and habitat fragmentation can decrease transmission of a parasitic nematode in a particular species of Australian lizard, the pale-flecked garden sunskink.

The new experimental research, published today in the journal Ecology, found that specimens of the blue and brown-colored, index finger-length skinks who live in isolated forest plots were 75 percent less likely to be infected with parasitic worms than their counterparts living in untouched, continuous forests — an indication that the parasite’s life cycle had been disrupted.

A decrease in parasite prevalence isn’t necessarily good or bad for an ecosystem, the researchers said, but it can result in dramatic changes.

“Parasites are a massive unseen component of an ecosystem and there so many that we don’t see,” said Associate Professor Kendi Davies of CU Boulder’s Department of Ecology and Evolutionary Biology (EBIO). “Parasites regulate populations and influence multiple hosts. It’s largely unknown how these complex interdependencies respond to changes.”

Habitat fragmentation in the form of deforestation remains a major threat worldwide. Scientists estimate that nearly one-third of global forests have disappeared, leaving behind a patchwork of ecological “islands” that can threaten food chains and alter long-standing species interactions

“Fragmentation is a big deal because it leads to loss of biodiversity and ecosystem functions” said Julian Resasco, lead author of the study and a postdoctoral researcher in EBIO. “It can also change the way diseases spread, with the potential to impact human health.”

The new study was conducted at the long-running Wog Wog Habitat Fragmentation Experiment, a 33-year-old continuously-run experiment in the eucalyptus forests of New South Wales, Australia. The site allows researchers to compare uninterrupted forestland to forest fragments that have been isolated by clear-cutting and burning.

Resasco zeroed in on skinks after a chance observation. While examining the gut contents of many historical specimens preserved in a museum, he noticed that the commonly-found lizards had been infected with a particular parasitic nematode. After consulting with Australian colleagues, he learned that it was, in fact, a brand new species.

“I wanted to quantify infections by these nematodes to see if fragmentation had an effect on parasitism,” Resasco said.

The nematodes use a small amphipod crustacean species as an intermediate host, which is in turn eaten by the skink, resulting in infection. But forest fragmentation significantly reduces the moist leaf litter habitat that these amphipods require, depriving the skinks of a meal and the parasites of a transmission pathway.

The study found that among skinks living in continuous forest, 55 percent contained nematodes compared to just 11 percent of skinks living in the fragments.

“We see the consequences of messing with key players in the landscape,” said Resasco.

The next step, the researchers said, is to think in even longer timescales. Now more than thirty years in at Wog Wog, parts of the landscape there have gradually changed from clear-cut to pine plantation forest, which could prompt a rebound.

“Pine forests are a pretty desirable place for the amphipods to live,” said Matthew Bitters, a doctoral researcher in EBIO and a co-author of the study. “So if they do recover, will that mean a rise in skink infections again? Or has something else emerged to disrupt the transmission?”

“Fragmentation research has a long history of studying species interactions such as pollination, seed dispersal and predation,” said Resasco. “Parasitism has received less attention but such research is important for understanding how landscape changes affect biodiversity and disease transmission.”

Tegu lizard DNA sequenced


This November 2018 video shows a tegu lizard.

From GigaScience:

The warm and loving tegu lizard becomes a genetic resource

The tegu, a South American lizard with its own heating system, has had its genome sequenced to an unprecedented level of quality

November 27, 2018

Summary: Researchers have sequenced the genome of the tegu, Salvator merianae: a lizard that has taken an evolutionary step toward warm-bloodedness. It is also a highly desired pet, that can often be house-trained; unfortunately, as part of the exotic pet trade, it has been released in new environments and become a threat to local species. This extremely high-quality tegu genome sequence will be of use to researchers in the fields of evolution, physiology and ecology.

Published today in the open-access journal GigaScience is an article that presents the genome of the tegu lizard, which has mastered a trick that is highly unusual in the reptile world: it can turn on its own heating system.

Most reptiles are not able to control their body temperature like mammals do and instead must rely on its environment, such as available sun and shade, to attain an optimal body temperature. The tegu, Salvator merianae, however, has taken a step towards being full-blown warm-blooded: It can raise its own body temperature by up to 10°C above its surroundings. Another, but more negative, aspect of the tegu is that is an invasive species and poses a serious threat to endangered species. Although it is a native of South American rain forests and savannas, the charismatic nature of the tegu — and that it can even achieve some level of house training, makes it an extremely charming pet that is much beloved by reptile aficionados. Unfortunately, international trade in exotic pets are one of the primary reasons that species enter new environments where they can become a menace to the native species. Given the tegu’s unique biological characteristics and its potential peril to the environment, the availability of an extremely high-quality genome sequence of this large lizard serves as a rich resource for identifying and analyzing the underlying molecular basis of these aspects.

The tegu genome sequence, provided by a team of researchers led by Michael Hiller at the Max Planck Institute for Molecular Cell Biology and Genetics in Dresden (Germany), is of unprecedented quality. To accomplish this the researchers used state-of-the-art technology to read the tegu’s DNA and assemble its genome sequence. The newly released genome sequence of S. merianae is more than two billion DNA letters long and contains more than 22,000 genes. It is the most complete assembly of any reptile genome so far and will also aid scientists to study other lizards and snakes.

By using so called “long read” (Pacific Biosciences) sequencing technology, the researchers were able to overcome some of the challenges of assembling reptile genomes. Hiller and first author Juliana Roscito explain: “Similar to other reptiles, a large portion of the tegu genomes consists of repetitive sequences, which occur many times in the genome. Repeats are a main problem when assembling a genome, especially when repeats are longer than the length of the sequenced DNA fragments, which results in gaps (breaks) in the assembly.”

The tegu is emerging as an interesting model species in its own right. One of the motivations for the authors to sequence the tegu genome actually related to their interest in another group of reptiles: snakes. The authors explain what they had in mind: “We were interested in studying limb loss in snakes and other reptiles. Since limbless reptiles had ancestors with fully developed limbs, we needed a well-assembled genome of a lizard with fully developed limbs as a reference.” Given that there are few reptiles with sequenced genomes, the authors decided to produce this themselves.

Another component of the article, especially given that reptiles are under-represented among. the vertebrates with sequenced genomes, the authors also provide a whole-genome alignment between the tegu and 16 other species. “We hope that these resources facilitate comparative reptile genomics to understand how unique morphological features evolved in this group of species and how vertebrate genomes evolve in general,” Michael Hiller and Juliana Roscito conclude.