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What is this lizard?
Seen in Hollywood, Florida, on a golf course. It may have been an escaped pet and was approximately 17" long.
Lizards are a widespread group of squamate reptiles, with over 6,000 species,  ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic as it excludes the snakes and Amphisbaenia some lizards are more closely related to these two excluded groups than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3 meter long Komodo dragon.
Most lizards are quadrupedal, running with a strong side-to-side motion. Others are legless, and have long snake-like bodies. Some such as the forest-dwelling Draco lizards are able to glide. They are often territorial, the males fighting off other males and signalling, often with brightly colours, to attract mates and to intimidate rivals. Lizards are mainly carnivorous, often being sit-and-wait predators many smaller species eat insects, while the Komodo eats mammals as big as water buffalo.
Still endangered: the Blunt-nosed Leopard Lizard
Dr. Rory Telemeco, Assistant Professor in the Department of Biology at Fresno State, seems fated for a career studying lizards … and maybe even saving them.
“I was a dinosaur nut as a kid,” he said. “Totally, I was the little boy in Jurassic Park.”
His passion for predators led him, ironically, to be involved in efforts to preserve the Blunt-nosed Leopard Lizard, which has long been on the endangered-species list.
“This species mostly eats arthropods — grasshoppers, spiders — but will also eat other lizards and small rodents if they get the chance,” he said. “They’re the biggest lizard out there. They’re one of the top predators.”
Top predators notwithstanding, they are federally listed as an endangered species — in fact, they are one of the inaugural species on the original list in the Endangered Species Act of 1973. And they are still at risk.
Dr. Telemeco is hoping that his work can change that. But then, he always did have a liking for lizards.
In college, his very first class at the undergraduate level was Zoology at 8 a.m. on Mondays, Wednesdays, and Fridays. His professor happened to work with … you guessed it, lizards.
Needless to say, the class appealed to Dr. Telemeco, despite the early hour at which he had to be on campus.
“I always liked reptiles, anyway,” he said. “So I started that year working to understand social behavior in Collared Lizards with my professor, in their habitat.”
Although Dr. Telemeco made several forays into trying other areas of study, such as working at a vertebrate paleontology lab for a few years as an intern, he eventually found that he was steering away from studying fossilized bones and more toward studying live lizards. Yes, lizards. Again.
“I also really like snakes,” he said, “but, due to my allergies to anti-venom serums, I decided there were enough people studying venomous snakes.”
It was when he received a Fulbright scholarship and did his master’s work in Australia that Dr. Telemeco began studying life history theory, which describes how evolution shapes how much energy species put into reproduction.
“The theory looks at what are the evolutionary pressures that act on animals to make reproductive decisions, what ends up being the optimal strategy,” he said. “At the same time, I became more and more aware of climate change, and how changes in the abiotic factors of the environment affect life history, especially in animals whose welfare is really linked to temperature.”
These two interests coalesced into … yes, once again, studying lizards … the Blunt-nosed Leopard Lizard, to be more precise. These lizards are endemic to the San Joaquin Valley and only live in fairly undisturbed desert habitats.
The more you learn about them, the more these little lizards seem incredible. They find ways to survive against the odds.
“As ectotherms, lizards historically have been thought of to be much under the whims of the environment,” Dr. Telemeco said. “Turns out, they have a lot of tools for modifying their body temperatures. They’re just not doing it metabolically, like the endotherms, mammals and birds, are.”
Endotherms use a lot of their energy to generate heat, but ectotherms use a lot of their energy for reproduction. Yes, that’s right. The Blunt-nosed Leopard Lizard is built to reproduce. Even so, probably due to environmental factors, the Blunt-nosed Leopard Lizard has a hard time keeping its numbers up.
Dr. Telemeco is part of a multi-agency collaboration with the U.S. Bureau of Land Management, Cal Poly San Luis Obispo, and the Fresno Chaffee Zoo performing range-wide work on northern and southern groups of the Blunt-nosed Leopard Lizard.
“We try to understand the ecology involved in preserving this species and what kind of habitat they need to have,” he said.
The Valley at one point was basically desert scrub and huge wetlands, and rapid changes in the environment appear to have negatively impacted the Blunt-nosed Leopard Lizard’s normal reproduction rate.
“It was a very different landscape a hundred years ago,” Dr. Telemeco said. “Probably because the environment is now so harsh with modern landscapes, these lizards only seem to live a couple of years in the wild, and they are not reproducing as much.”
In order to find a way to increase the lizards’ chances of survival, he and his students put temperature-sensitive radio collars on them, then use stationary antennas in the landscape to pick up the signals that allow for real-time body temperature measurements on the animals throughout the year.
“We’re looking at some of these desert landscapes they live in,” Dr. Telemeco said. “Some of them look like just bare earth, with no cover, and others have spotted shrubs on them, the most common being Ephedra californica, or the California jointfir, or cañatillo. We are testing how important the shrubs are to Blunt-nosed Leopard Lizard habitats.”
Being a lizard isn’t as easy as it sounds. Basically, the landscape is too hot during the day and too cold at night for the lizards to be active, so lizards have to resort to going into their underground rodent burrows.
“What we’ve found is all the microhabitats in landscapes without shrubs get way too hot, deadly hot, late in the day,” Dr. Telemeco said. “But the lizards are still maintaining a good temperature, by going into their burrows, probably deeper underground than we’ve measured … that’s their only option, to go underground. But if they can just climb a couple of inches above ground into a shrub, they can stay out happily longer in their habitats.”
Measurements confirm that lizards can stay above ground more often during the day if they have shrubs available.
“It looks like areas with shrubs give them an extra three hours a day in which they can be out and about, living their lives out of the underground burrows,” he said. “We’re trying to see how they can use the landscape to maintain their body temperatures, and what’s constraining them when they can be out eating and reproducing. Our study results potentially put more focus on preserving landscapes with a complex shade structure.”
Why be out and about? Well, for an endangered species, it’s critical to reproduction. Egg clutches are typically about four eggs for the Blunt-nosed Leopard Lizard. Dr. Telemeco’s efforts to monitor reproduction include using portable field ultrasound on the females to find out how the eggs are developing, how many eggs are developing, how big the eggs are, and how much energy the lizards are devoting to reproduction.
“They can produce three clutches per season, from about April through the very beginning of July,” he said. “Outside that time, they go into the non-reproductive phase of their life.”
So do lizards make good parents?
“With lizards, the diversity of things that they do is very extreme, everything from individuals that will lay eggs and leave, which is probably the most common,” he said. “Then there are species of skink that will rotate the eggs during incubation and stay with them during development. Then there are alligator lizards that will guard the nest. There are even species that give live birth, keeping their developing young in their bodies.”
What do the Blunt-nosed Leopard Lizard do? Scientists know they lay eggs, but beyond that aren't really sure because a natural nest has never been observed. The best guess is that they typically lay the eggs in an underground nest and cover them with dirt. Sounds like easy parenthood, doesn’t it? But only a small number the young seem to be surviving.
Finding optimal habitats could be the key to reversing that. Dr. Telemeco and his teams also study what the lizards’ home ranges are, figuring out exactly how they’re using the landscape.
One thing is for sure … this California native species is lucky to have someone like Dr. Telemeco looking out for its future.
The flying lizards of the genus Draco (family Agamidae) are widespread in Southeast Asia and southwest India. The genus is composed of approximately 45 species, with 39 currently recognized and several new species awaiting description. Flying lizards are famous for their gliding locomotor strategy, which they use to move between trees in their habitat of tall, dipterocarp-dominated, forests. All Draco lizards are strictly arboreal, and all share anatomical specializations that enhance aerodynamic lift during gliding, including a patagium supported by elongated thoracic ribs and expandable throat lappets supported by the hyoid apparatus. Together, the patagium and throat lappets serve as the primary airfoils and substantially reduce wing loadings relative to those of less specialized gliding or nongliding lizards. Here we review the evolutionary background of aerial performance in lizards generally, discuss morphological features and ecological contexts specific to gliding in Draco, evaluate the allometry of gliding performance in this taxon, and conclude with a functional interpretation of the morphologies of extinct reptilian gliders that show strong morphological parallels to flying lizards.
Lizard Identification - Biology
The Biogeography of Sceloporus occidentalis
by, Jeremy D Bailey student in Geography 316, Fall 2001
Sceloporus occidentalis, commonly known blue-bellied lizard is a familiar fixture in the Western United States. Anyone who hikes and enjoys the outdoors knows this lizard by sight. How many of these lizards have we almost stepped on, caught or saved from the claws of our cats over the period of our lives here in the Western United States? Let me now introduce you to the Western Fence Lizard, (Sceloporus occidentalis)
(Patricia A. Michaels 2001)
TAXONOMY: Photo: John Sullivan
| Kingdom: Animal |
Species: Sceloporus Occidentalis
Description of Species:
Sceloporus occidentalis has coloration on the underside of its body, males have blue patches on their underarms, throats and on the undersides of their abdomens, females have much less of this coloration (Figs 2 and 3). Sceloporus occidentalis ranges in size from two and a quarter to three and one half inches in snout-vent length (Stebbins,1954). Its dorsal scales range in color from brown, tan, gray and sometimes black (Schwenkmeyer,2001). Their scales overlap each other and appear pointy and rough, although not shiny in appearance (Fig 1). These lizards like all reptiles are ectothermic (cold blooded) and need to sun themselves at every opportunity in prominent places like rocks and fence posts making them easy prey for birds and snakes as a result the lizards have developed fast reflexes. Sceloporus occidentalis lives up to five or six years, but because of predators they typically live only one year. (USGS,2001)
Figure1: Scale Comparison (Sceloporus occidentalis,S.Undulatus)
Source: Stebbins 1954
|Figure 2: Sceloporus occidentalis, Male coloration||Figure 3: Sceloporus occidentalis, Female coloration|
Habitat/Distribution: Sceloporus occidentalis belongs to the highly successful cosmopolitan Phrynosomatidae family (Stebbins,1954) This species is eurytopic and dispersed in great numbers across the Western United States. Its distribution continuously ranges geographically from Southwestern Canada, Oregon, Washington, Western Idaho, Nevada, Utah, California to Northwestern Baja California (Figs 4 and 5). In these regions the lizard ranges from the coastal areas to the mountains up to 6,000ft. Their closest relative the eastern fence lizard, (Sceloporus undulatus) is almost identical to Sceloporus occidentalis with the exception of a slightly different pattern, number of scales and range of distribution (Fig5). Sceloporus undulatus can exist in mountainous areas while Sceloporus occidentalis does not with the Rocky Mountain Range being the major barrier between them (Stebbins,1954), (Fig5). The blue bellies wide array of habitats include moderately open coniferous forests, rocky canyons, slopes and woodlands. It also enjoys sagebrush and grassland habitats, but excludes desert environments. Their wide distribution gives them access to abundant food sources. These lizards feed on insects like beetles, flies, caterpillars and ants as well as arthropods(Brookshire,2001). The blue belly can typically be found near the ground or on fence rows and on the branches of bushes and shrubs. They typically make their homes in old tree trunks, under rocks and in wood piles. Due to their ectothermic nature the blue bellies are diurnal the seasonality of their habitats causes the lizards to hibernate or go into periods of inactivity in the cooler winter months. They then reemerge around late winter early spring, March (Karr,1999)
Maps of Distribution: (CAS 1995) (Stebbins 1954)
Figure 4: Sceloporus occidentalis, California Distribution
(Yellow Green=Sceloporus occideantalis range)
Figure 5: Distribution N. America,
(Sceloporus occidentalis, S. undulatus Distribution 1-4)
Breeding: During the spring Sceloporus occidentalis starts to reestablish its home territory in the same area year after year, which is usually around .01 hectars (Giorni,1996). A females territory is almost always two thirds the size of a males (Sheldahl,2000). Both defend their hibernation area, food supplies and home range throughout the year. During this time both genders will establish dominance over their territory from other lizards by posturing and posting chemical cues or cent marks. As a result there is usually only one lizard per sunny boulder or tree trunk.
During the breeding season males will sit atop their territory to both fend off other males and to attract females. The lizards begin to mate their second year, the males will do what looks like a rhythmic set of pushups to attract mates. Females are usually closer to the ground and harder to spot than males. Once ready to mate she will appear and the male will vertically flatten his body to display his brilliant blue colors (Schwenkmeyer,2001). He then holds the females neck in his jaws while mating commences. If the female changes her mind during copulation she turns on her back and kicks the male off with all four legs (Angilletta,2001). During mating the normally tan to brown dorsal scales on the male will turn a brilliant blue (Brookshire,2001). At present it is unknown if the couple is monogamous during the breeding season.
To assure species success the female will have two to three clutches per breeding season. She will expend more energy in the present season in case of her death before the next. Her first clutch will have the largest egg size and the final the smallest. To compensate for the difference in egg size the female will expend more energy on the care of the last clutch than the first, to maximize offspring survival (Angilletta,2001). Once the eggs are laid they can range in size from six to fourteen millimeters, she buries them under shallow moderately moist soil (Angilletta,2001). If consistent with similar species of reptiles the female will bury and care for the eggs without assistance from the male. The eggs usually hatch after two months in late April to June or July. Clutch sizes can range from three to seventeen and appear to increase with higher latitudes larger females typically have more offspring (Schwenkmeyer,2001). After a couple of months the infants emerge at around twenty six millimeters in snout-vent length. Most of their growth will occur during their first year of life.
Evolution: This species breeding and territorial behavior are a result of millions of years of evolution. The first reptiles evolved from amphibians around 250 million years ago during the Carboniferous period when reptile species diversified, and multiplied, to become the dominate large animal on the planet. In the Jurassic Period, around 65 million years ago, there was a planet wide mass extinction and reptile dominance ceased. All that remain of the reptiles are the 6,000 known species that survived the mass extinction (Cambell 1993).
Presently, these 6,000 species are divided by herpetologists into taxonomic levels to assist the classification of their evolutionary patterns, through morphological classifications (Cambell 1993). This process is also applied to the 3,000 known species of lizards. Through morphological examination and comparison herpetologists have traced the evolution of specific families and genus of lizards (Stebbins 1954).
The Phrynosomatidae family is cosmopolitain and differs little in morphology, habitat and reproduction preferences throughout the world. Evidence suggests the Phrynosomatidae family originated in one unknown area and spread with continental drift. Several genus and species evolved from this family due to the isolation of phenotypes and challenges of climate and predation. These genus are further differentiated by morphological characteristics (Stebbins 1954), (Figure 6).
|Sceloporus occidentalis is distinguished by several unique morphological traits, Stebbins differentiated the species by morphological uniqueness by stating that, "Scales on the back of the thigh are larger, pointed and keeled more than sceloporus undulatus, dorsal scales usually larger-about 35 to 55 (average 41), between interparietal plate and line connecting posterior surfaces of thighs, adults usually over two and three fifiths inches and usually without rust on the lower sides and a single blue patch on the throat (Stebbins 1954)." These characteristics can be traced to an originating species in the genus as well as the family (Figure 6).|
|Figure 6: Morphological Tree (Stebbins 1954)|
Other interesting facts: A protein discovered in the blood of Sceloporus occidentalis and S. undulatus kills the bacterium that cause lyme disease. Ticks are hosts to the bacteria, Borrelia birgdorferi and transfer the disease through biting. It has been discovered that ticks who have bitten Sceloporus occidentalis were disinfected of the bacterium. The species has evolved an immune response that kills Borrelia, not only in themselves but in parasites as well (Karr 1999). I assume the eastern fence lizard, Sceloporus undulatus developed this resisitance first because, lyme disease developed in the eastern United States. The resistance remained when the Rocky Mountains isolated the eastern and western fence lizards. Who would have assumed that one of the most recognizable species of lizard in the American west would hold a cure for lyme disease, this is true natural selection at work.
Interesting Insights from the Crocodile Skink!
The crocodile skink is not only a fascinating organism – it shows several different biological concepts in action!
Speciation on Islands
Several DNA studies of crocodile skinks have shown that skinks populations have become separated and reunited over time, as ocean levels rise and fall around island chains. Most crocodile skinks are endemic to the island chains north of Australia – a chain of islands that have experienced dramatically different ocean levels through the millennia.
When the ocean level is low, the islands become connected by a series of exposed sandbars and strips of land. These passageways allow skink populations to travel to new islands. When the water levels rise, the populations become isolated from each other. Over time, this can lead to allopatric speciation – a type of speciation that results from a geographical separation.
Though the conditions on each island are similar, each population of crocodile skinks has slightly different selective forces that lead to different evolutionary paths. Forces like genetic drift slowly change the makeup of each population. Populations of skinks that have been separated for hundreds of thousands of years can easily become distinct species. This is like how a single crocodile skink ancestor evolved to become 10 different species spread throughout the Indonesian islands.
To tell the difference between a male and female crocodile skink, you simply look at the bottoms of the feet.
Males have distinct pores – known as “volar pores” – that are theorized to release scents as the males travel around. While more research needs to be done on crocodile skinks specifically, this is a very common trait in many terrestrial animals.
In water, scent-marking does not work because substances quickly dissolve into water and are evenly distributed – making the source impossible to find. In the air, however, scents stay more concentrated near their source and allow animals to follow a concentration gradient.
Since female crocodile skinks do not have these secretory pores on their feet, it is assumed that male crocodile skinks are secreting an attractant to lead females to the male. This is backed by the observation that crocodile skinks are solitary, shy animals – a scent may help them find each other while remaining hidden from other animals!
Maternal Care in Reptiles
Interestingly, female crocodile skinks show a high level of parental care. Some reptiles species, such as the Green Sea Turtle, simply lay their eggs in a nest and leave them to hatch – months later.
The crocodile skink, on the other hand, lays only 1 egg and wraps around it tightly during its entire development! Plus, newborns stay with their mothers for up to 2 weeks after hatching. That makes crocodile skinks one of the most committed reptile parents around.
This also shifts where crocodile skinks fall all the spectrum of reproductive strategies. Other reptiles are mostly r-selected organisms (they produce many eggs and exhibit little parental care). Since crocodile skinks produce only 1 offspring at a time and protect it for up to 2 weeks, this shifts their reproductive strategy closer to K-selected organisms that invest heavily in each offspring.
Though humans and other K-selected species invest far more into their offspring, the crocodile skink is certainly convincing evidence that reproductive strategies have evolved to fall on a wide spectrum and that a common ancestor like a fish could have led to advanced parental care – such as that seen in mammals!
While the experiment was more than 30 years in the making, it was not by design, according to Duncan Irschick, a study author and biology professor at the University of Massachusetts, Amherst.
After scientists transplanted the reptiles, the Croatian War of Independence erupted, ending in the mid-1990s. The researchers couldn't get back to island because of the war, Irschick said.
In 2004, however, tourism began to open back up, allowing researchers access to the island laboratory. (Read: "Kayaking the New Croatia" in National Geographic Adventure Magazine.)
"We didn't know if we would find a lizard there. We had no idea if the original introductions were successful," Irschick said. What they found, however, was shocking.
"The island was swarming with lizards," he said.
The findings were published in March in the journal Proceedings of the National Academy of Sciences.
Tissue regeneration is a fundamental evolutionary adaptation, which is well known in lizards that can regenerate their entire tail. However, numerous parameters of this process remain poorly understood. Lizard tail serves many functions. Thus, tail autotomy comes with many disadvantages and the need for quick regeneration is imperative. To provide the required energy and materials for caudal tissue building, lizards are expected to undergo a number of physiological and biochemical adjustments. Previous research showed that tail regeneration induces changes in the digestive process. Here, we investigated if and how tail regeneration affects the digestive performance in five wall lizard species deriving from mainland and island sites and questioned whether the association of tail regeneration and digestion is affected by species relationships or environmental features, including predation pressure. We expected that lizards from high predation environments would regenerate their tail faster and modify accordingly their digestive efficiency, prioritizing the digestion of proteins the main building blocks for tissue repair. Second, we anticipated that the general food shortage on islands would inhibit the process. Our findings showed that all species shifted their digestive efficiency, as predicted. Elongation rate was higher in sites with stronger predation regime and this was also applied to the rate with which protein digestion raised. Gut passage time increases during regeneration so as to improve the nutrient absorbance, but among the islanders, the pace was more intense. The deviations between species should be attributed to the different ecological conditions prevailing on islands rather than to their phylogenetic relationships.
Admixture determines genetic diversity and population differentiation in the biological invasion of a lizard species
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The Traveling Lazarus Lizard
Around 1951, a 12-year-old boy and his family returned home to Cincinnati, Ohio from their vacation in Italy. Wanting a souvenir of the trip, the boy had stuffed around 10 lizards into the socks in his suitcase to bring home with him. The lizards not only managed to survive this journey, but thrive in their new home. Today, they’re easily spotted in the city and surrounding areas.
The Lazarus lizard, surprisingly named after the family responsible for their relocation and not their ability to detach and regrow their tails, has become part of the city’s identity. Lazarus lizards are found in murals, on carousels, and the original neighborhood they were introduced to is often unofficially marked on maps as Lizard Hill in their honor. And while their origin story might sound like a local legend, it has actually been proven as scientific fact.
Lizards Take Cincinnati
George Rau, stepson of Fred Lazarus III, came forward in 1989 as the one responsible for transporting the lizards. George’s account of what happened matched up to what researchers were able to determine themselves, but it wasn’t until 2013 when University of Cincinnati biology student Cassandra Homan compared the genetic profiles of the Lazarus lizards in Cincinnati to those in Europe that the truth became clear.
Homan’s research showed that not only were the Lazarus lizards related to the common wall lizards of Milan, but there was also “a very significant bottleneck” in the genetic diversity found in the US, which is attributed to having a very small starting population. It’s estimated that not all of George’s lizards survived long enough to reproduce, and the data suggests the genetic diversity only comes from 3 of the original 10. The most genetic diversity that is present was found around Lizard Hill, which further supports it as the original introduction site. There have been an estimated 33 generations of lizards from the first introduction of the species to Cincinnati, and because such specific information is known about their arrival the lizards have been a valuable case study for researchers looking into evolution.
While the area has embraced the Lazarus lizards, they are still technically an invasive species. He might not have realized it at the time, but 12-year-old George was lucky he didn’t alter his home’s environment even more than he did. The climates of Cincinnati and Milan are actually pretty similar, so the lizards were able to easily adapt to their new home. But more importantly, their introduction also didn’t really present a threat to the species already present in the area.
This video from cincinnati.com explains how locals view their invasive neighbors.
Lazarus lizards don’t really have any unique predator or prey relationships compared to other species in the environment, meaning they aren’t interfering with their neighbors’ resources. Researchers believe there was an "environmental niche" that wasn’t filled before the lizards were present, so their introduction was relatively smooth. Still, the purposeful introduction of Lazarus lizards to new areas is illegal, in case their introduction to a new area has more drastic results. This has definitely been the case in British Columbia.
History Repeats Itself
Around 1967, Rudy’s Pet Park in Saanich was home to about a dozen Lazarus lizards, or common wall lizards as they’re referred to outside Cincinnati. Somehow, either accidentally or purposefully, the lizards were released from the zoo and spread much like they had in Ohio. Unlike their last introduction, the common wall lizards did not integrate smoothly into the neighborhood. Today their numbers have skyrocketed to anywhere between 500,000 and 700,000, and while that’s a smaller population than the estimated million in Cincinnati, these lizards have a much greater impact on their surrounding area.
Predators are unable to keep up with the population, and the lizards are feeding on pollinating bees, snakes, and potentially other endangered species native to the area. Their territory is also increasing almost directly due to human involvement. Kids with George’s same instincts try to make them pets and carry them home, or the lizards hitch rides on shipping trucks and end up in a new environment. There’s currently no government plan to curb the growing lizard population besides reporting sightings to the British Columbia Invasive Species Council, and research into the full extent of their impact is ongoing.
A scientist in British Columbia explains the impact the lizards have on the local environment in this video from CBC News.
While the impacts of the Lazarus lizard’s presence is obviously very different between Cincinnati and British Columbia, the similarities between their introductions is an interesting example of how humans impact our environment. When we think of our activities that impact Earth, we often think of the more abstract, faceless contributors of wide scale pollution and climate change. The case of the Lazarus lizard should not only serve as a reminder to consider how easy it is to unknowingly cause damage to an area, but also give us hope that individual actions can create a domino effect into positive change. If one 12-year-old boy’s vacation souvenir can change a city’s iconography, the possibilities for positive environmental impact are endless.