• Abstract and Figures
• Public Full-text

Autumn 2006 Just an Ordinary Lizard Volume 26, Number 3 by Don Roberson Iguanidae (which includes our fence lizards): “The pushup display is used by one lizard to In the rural county where I was raised, we tell other lizards, ‘This is my space. Keep your called ‘em “blue-bellies.” They were everywhere: distance.’ All ages, including hatchlings, and both running up logs, climbing up fences, basking in sexes perform pushup displays. Male iguanids the sun. These were just basic gray lizards with perform more vigorous display, called challenge chevron patterns on the back, and could be hard displays. The challenge is similar to the pushup to spot until they ran. If you were fast enough to display but may include all four legs, extension grab one, and turned it over, odds were that you’d of the throat sac, and other movements that make see two blue belly patches. It was a nice lizard the lizard appear larger and more colorful. The -- it didn’t bite you when you caught it -- but it was just your ordinary lizard; nothing to get excited about. As I grew older, I spent most of my free time looking through binoculars -- at birds, not lizards. Yet the lizards were still around, and I often saw them peripherally when birding, in- cluding at some of the National Wildlife Refuges around the Bay Area. My Stebbins’ field guide A[ Field Guide to Western Reptiles and Amphibians in the Peterson field guide series] called them Western Fence Lizard Sceloporus occidentalis, a widespread species from northern Baja California to Washington state, and inland to western Utah. As I traveled around California chasing after birds, fence lizards were often encountered from sea level to high mountains. One summer morning in 1981, while birding in Andrew Molera State Park in coastal Monterey County, I came upon a Western Fence Lizard doing “push-ups.” This is not a rare be- challenge display is most often performed during A complex pattern of havior but this guy was doing quite exaggerated the spring, when males are establishing their ter- chevrons across its back push-ups and, as he held the “up” position, his ritories and courting females. The male performs the challenge display from prominent rocks make the Western Fence otherwise flat throat popped out in an exagger- lizard difficult to spot ated dewlap. I knew that tropical anoles were or perches within his territory or in territorial known for exaggerated throat-flap displays, but disputes when an intruding male comes too close. among the rocks – until our ordinary lizard? This was unanticipated. Battles between males are rare, and disputes it runs. Photo June 2003 Later I found a discussion of “pushup” are usually resolved through challenge displays at Garrapata State Park, displays in a wonderful little booklet called The followed by a chase.” Monterey County. Western Fence Lizard is a member of the Lizard-Watching Guide (1994) by Sherburn Photo: Dan Roberson Sanborn. It covers the California deserts but widespread New World genus Sceloporus. This his explanation applies to most members of the Continued page 2 1 Just an Ordinary Lizard from page 1 word is a Latinized form of a Greek word that guide, you’ll find that he recognizes no subspe- combines “skelos,” meaning “leg,” and “porus,” cies at all. This is because scientists are currently meaning “pore or opening.” This refers to the studying Sceloporus occidentalis. Their results femoral pores on the underside of the hind legs. will determine how many subspecies or even Focusing on the rear surface of the hind legs for a full species there are within populations of this yellowish or orange coloration will help separate lizard, and where they are distributed. In doing this species of Sceloporus from other Sceloporus, an on-line search, I found an announcement that such as Eastern Fence Lizard Sceloporus un- Dr. James Archie, biology professor at California dulatas that occurs from S. Utah east, and from State University, Long Beach (CSULB), received Sagebrush Lizard Sceloporus graciosus that a grant from National Science Foundation in occurs within the range of Western Fence Lizard. 2000 to study the geographical patterns of genetic Although the Western Fence Lizard occurs within variation in the Western Fence Lizard. the same range as the Sagebrush Lizard, they In an interview given to the CSULB prefer different habitats. I’ve since learned that newspaper at the time, Dr. Archie said: “In in Monterey County, for example, Western Fence studying the western fence lizard, my students Lizards exist in all types of habitats – coastal and I have found that different genetic groups, or scrub, riparian, oak woodland, chaparral, and clades, of the lizard are isolated geographically, rocky grasslands – but that Sagebrush Lizard is creating boundaries between different genotypes. confined to montane chaparral at high elevations Yet, there are no physical obstacles to prevent the in the Santa Lucia Mountains. dispersal and flow of genes between the various Fence lizards genetic groups. It’s not known why this isolation eat a lot of insects or separation occurs, but I’m hoping to find an and spiders, but explanation for the presence of these boundaries.” they also have many In the field, Dr. Archie and his students clutches of eggs and use extended fishing poles to capture lizards hatch many baby unharmed by putting a small noose around lizards. These baby their heads. After being caught, the lizards are lizards are, in turn, measured, scanned with a computer scanner or preyed upon by photographed. A piece of the tail is also taken larger invertebrates, to permit genetic analysis. Then, the lizards are including scorpions released. “The research will investigate the evolu- and black widow spi- tionary significance of the clade boundaries. The ders, not to mention findings have the potential to make a substantial many snakes, jays, contribution in the area of evolutionary biology hawks, and Greater of speciation.” In addition, Dr. Archie “noted that Roadrunner. the application of the research to conservation An Exaggerated push- While birding in eastern California, I biology could also be important.” up with a flared throat sometimes marveled at how big and black- I emailed Dr. Archie to ask how the project dewlap and bright blue colored some of the fence lizards there were, was going, and he replied, “The story in Western belly patch is both a especially in the rugged terrain north of Death Fence Lizard is quite complex,” he wrote. territorial display and Valley. Early editions of the Stebbins’ field guide Genetic research and DNA sequencing resulted in listed four subspecies of Western Fence Lizard: a finding that “there are about 15 distinct genetic an enticement to female Northwestern Fence Lizard S. o. occidentalis groups (=clades) within the species, all of which lizards. Photo June 1981 (the nominate race ranging from Washington are restricted geographically in their distribution” at Andrew Molera State state south through all of northern California), with very little overlap. Some of the clades differ Park, Monterey County. the Great Basin Fence Lizard S. o. biseratus up to 9% in their DNA sequences, “which is quite Photo: Don Roberson (Great Basin and southern California), the Sierra large and indicates that the species is quite old Fence Lizard S. o. taylori (in the southern Sierra (likely >10 million years).” In the San Francisco Nevada) and Island Fence Lizard S. o. becki Bay Area, for example, there are three clades: (a) (on some of the California Channel Islands). Marin County north into Washington state, (b) [The latter is named after Rollo Beck, a famed San Francisco peninsula south to Santa Cruz and bird collector at the turn of the 20th century.] east to Livermore, and (c) Big Sur to Morro Bay. It turned out that while the “Great Basin Fence There is yet another clade that exists from Lizard” was “often gray or black below,” this was eastern Santa Clara County east across the San not considered to be a key character. In the 1990s, Joaquin Valley and includes the southern Sierra more subspecies were recognized by the Center for Nevada. That huge mountain range has been a North American Herpetology (CNAH). The CNAH barrier to fence lizard dispersal, although there is website at www.naherpetology.org is a great gene flow around both the north and south ends internet resource about reptiles and amphibians. of the Sierra. The nominate subspecies, including In the 2003 edition of the Stebbins’ field lizards in Marin County, may represent a differ- 2 3 Don Roberson is a Monterey- Just an Ordinary Lizard continued based amateur naturalist with ent species that ranges north into Washington California – but have survived to this day in a expertise in bird distribution state and east across the northern edge of the variety of forms. “I’m afraid the story goes on and identification. He is the Sierra Nevada, but not into the Great Basin. Dr. author of four books on birds, and on,” says Dr. Archie. The complexity of the mostly recently “Monterey Archie and his students are currently looking situation – and trying to match up which histori- Birds” (2003). His web site at the boundary areas between these lizards, cal events impacted which of the clades, and how www.montereybay.com/creagrus and those from the Great Basin, in places like – have delayed formal publication of the research. focuses mostly on birds in Reno, Susanville, and Bend, Oregon. “In the Dr. Archie hopes to have a paper submitted for Monterey County, plus such Marin County clade, the DNA data suggest that publication in summer 2006. widely flung topics as the “Bird there was a post-Pleistocene range expansion What is clear is that we cannot look at our Families of the World” and birding trip reports from around north from northern California into Oregon and fence lizards in the same way again.

Load more

  16

Copy Link