Symposia and Workshops
Herpetology of the Californias
Alphabetical by Presenter
Phylogeography of the western
fence lizard (Sceloporus occidentalis):
James W. Archie
There are currently six recognized subspecies in the western fence lizard (Sceloporus occidentalis). This diversity is a reflection of the observed geographic variation in morphology within this species. The species occurs from sea level to over 10,000ft and from Baja California Norte to Washington state in highly diverse habitats. I analyzed within species phylogeography based on nucleotide sequence variation in a 950bp segment of mtDNA (ND4-Leucine). One to three individuals were sequenced from each of more than 50 populations throughout the western part of the species' distribution (Baja and northern California, Oregon, & Washington). Sequence divergence between sampled populations ranged from 0.0% to more than 17%. Four major clades were identified including: 1) a northern clade extending from Marin County north to Washington and east to the western side of the Sierra Nevada as far south as Sonora Pass (north of Yosemite); 2) a central and southern Sierra Nevada plus San Joaquin Valley clade that includes populations from San Mateo and Santa Clara Counties; 3) a southern clade that includes all of southern California plus central coast populations and populations from the eastern edge of the Sierra Nevada and western edge of the Great Basin north to western Oregon; and 4) Santa Cruz Island. Within each of the first three major clades there are distinct minor clades that maintain geographic integrity. Each of the major clades is composed of populations from one or at most two of the named subspecies in the species: 1) S. o. occidentalis populations comprise the northern clade; 2) S. o. biseriatus plus S. o. taylori comprise the Sierra-San Joaquin clade, 3) S. o. longipes is paraphyletic with respect to S. o. bocourtii from the central coast, but the two together comprise the southern California + Great Basin clade; and 4) S. o. becki comprises the Santa Cruz Island clade. The geographic and genetic distinctness of the clades suggest that these clades reflect distinct, and fairly ancient, historical events. Clade boundaries are distinct suggesting lack of mtDNA gene flow, in spite of apparent nuclear gene flow. The results indicate that the Sierra Nevada are an effective barrier to dispersal and gene flow between eastern and western clades. The genetic uniformity of eastern Sierra populations and the lack of divergence from southern California populations (less than 2% sequence divergence between populations separated by 500km) suggest a fairly recent dispersal event. The most morphologically distinct subspecies, S. o. taylori, is indistinguishable from low elevation S. o. biseriatus, but, because only a single population was sampled, the origin of this distinct morphotype is still in question.
Historical reminiscing by a research assistant of Laurence Klauber
Bayard H. Brattstrom
As Laurence Klauber's research assistant for many years, I will share an unique insight into his life as both a man and a scientist. From the trials and tribulations of moving the herpetological collection from the zoo to the museum after the end of World War II to working in the laboratory at Klauber's house, I will pass on many stories about the daily going-ons of an era long passed, yet still influencing us all today.
James R. Dixon
The terrestrial reptile fauna of the Gulf of California (Sea of Cortez) Islands has changed considerably from the early list of 74 taxa of reptiles by Van Denburgh (1922), to Murphy's list of 129 taxa of reptiles in 1983. During our Expedition in 1964, the known terrestrial reptile taxa stood at approximately 105 taxa.
With the recent technology advances in electrophoresis and DNA analysis, the number of taxa have increased greatly. Correspondingly, there has been a rapid surge in scientific publications, resulting in a 1977 symposium (published in 1983) on "Island Biogeography of the Sea of Cortés", edited by Case and Cody.
Taxonomists continue to debate the usefulness of informative systems as single entities, e.g., immunological techniques, electrophoresis, DNA, morphology, behavior, ecology vs. whole system approaches, concept of cladistic modeling, and consensus trees. Regardless of these arguments, there is yet much to be learned from the reptiles of the islands, including studies for their conservation.
The effects of urbanization on the herpetofauna of coastal southern
We are conducting an intensive study of the herpetofauna of the low elevation scrubland communities of the California Floristic Province between the Whittier Hills and the Mexican Border. Our research focuses on life history of species and the effect of habitat fragmentation on species distributions. This is a region of expanding urbanization with a human population in excess of 16 million residents. We utilize pit-fall traps with drift fences to trap reptile and amphibian species at 26 study sites, consisting of multiple sampling stations, ranging over an environmental gradient of habitat, elevation, and climate. The trapping design captures 40+ species of reptiles and amphibians. It is an effective way to sample the majority of the terrestrial fauna, particularly those species that are difficult to inventory because of nocturnal, fossorial, and cryptic habits. We found that most species occur broadly over this area, and that there is a core group of 14 species that occurs evenly at the majority of the study sites in each county. We are also creating the historic (early 1900's) herpetofauna communities of our study sites in San Diego County using the records of Klauber, and others, to determine which species may be at greatest risk of decline in coastal Southern California. Several of the sensitive species we are studying are widespread across the region, and if proactive conservation steps are taken, many of these could be brought out of risk for future listings.
Field observations of California amphibians and reptiles
William C. Flaxington
The herpetofauna of California varies along with its many diverse geographical regions. Many trips to these regions were made from 1989 to 1998, to locate and observe common and rare animals. The information collected desire to fill missing gaps in the knowledge of Herpetology, by providing elements of biological interest, peculiar activity or habitat, and identifying precise locations to use in overall analysis of Herpetofauna. Principal geographic regions explored during my studies include: San Gabriel, Santa Ana, Sierra Nevada Mountains, Coast Ranges, Great Basin, Mojave, Colorado Deserts, and other regions. Although explorations were focused on animals of these particular regions special effort was often given to locate a single species. Some of these include: Bufo californicus, Crotaphytus bicinctores, Crotalus scutulatus and many others.
In the mountains, lush forest communities cover much of the Coast Range, Sierra Nevada and mountains of Southern California. Here a variety of forest animals were discovered. Some animals encountered include: Ambystoma gracile, Clemmys marmorata and Salvadora hexalepis. Treacherous stormy conditions, allowed the observer to encounter a great variety of amphibians that are seldom exposed in the open, such as Taricha torosa and Ensatina eschscholtzii.
Surprisingly, Aneides lugubris, a species generally found at low elevations was discovered at night when climbing a moss-covered cliff, at 6400 feet. During the daylight when exploring isolated locations, secretive snakes such as Lichanura trivirgata, Lampropeltis zonata, Coluber constrictor and even Hypsiglena torquata have been detected. The mountain regions possess a wealth of undiscovered animals that only with persistent research, will biologists truly be able to reveal the strange animals that frequent our mountains.
Opposed to the mountain communities, the deserts are rather barren. Studies were conducted in three distinct regions: the Great Basin, Mojave and Colorado Deserts. In the desert, hundred of observations were gathered, from the widespread Masticophis flagellum to the seldom seen Elgaria panamintina. Research was conducted during the extreme, midday heat and during cool, pitch-black nights.
One unusual pattern found, were Coleonyx variegatus coinciding with scorpions. Oddly, the gecko and scorpion were commonly detected at the same site, possibly representing a type of inherent relationship. Another unusual behavior seen were repugnant defensive maneuvers performed by nocturnal snakes. Arizona elegans were discovered many times to sway its body in a bizarre, nauseated motion. While Rhinocheilus lecontei exhibited an extraordinary mock-death act, by coiling on its back and expelling blood. The desert's extreme temperatures often required searching in harsh human conditions. However, this is often needed in order to record seldom seen or unusual animal behavior.
Because observations revealed that animals are intricately connected with the environment, it is essential to determine what land supports relatively high populations and varieties of animals, to specifically protect those areas from destruction. Thus, field studies are important when establishing new wildlife reserves or taking land into consideration before human development occurs. Thus, a ten year series of field observations is vital to confirming natural patterns and habitats while exposing aberrations for further study.
Composition of helminth communities
S.R. Goldberg* and H. Cheam
Five hundred seventy two Sceloporus occidentalis from two nearby populations in Los Angeles County, California were examined for helminths: 200 from the San Gabriel Mountains (montane ca. 1584 m elevation) and 372 from the Puente Hills, Whittier (lowland ca. 150 m elevation). The component helminth community of the montane fence lizard population consisted of four species: two species of cestodes, Mesocestoides sp. and Oochoristica scelopori and two species of nematodes, Physaloptera retusa and Spauligodon giganticus. The component helminth community of the lowland fence lizard population contained three species; Mesocestoides sp., Physaloptera retusa and unidentified acuariid larvae. The two helminth communities were dissimilar in composition. Each host population must be examined: helminth community composition cannot be assumed.
Evolution of the Peninsular Herpetofauna of Baja California, Mexico
L. Lee Grismer
The evolution of the herpetofauna of Baja California has been greatly influnced by the separation of the Baja California peninsula from mainland Mexico and the formation of the Gulf of California. Being that this separation proceeded from south to north, most species endemic to southern Baja California show a trans-gulf sister group relationship with taxa from southwestern mainland Mexico. As the Gulf of California extended northward into southern California, it effectively separated populations that were continuosly distributed around the head of the gulf into allopatric eastern and western populations. After the gulf regressed to its current position, many of these populations have come back into contact and are represented by parapatric sister groups currently situated in the vicinity of the head of the Gulf of California. The regression of the Gulf of California and the simultaneous formation of mid-peninsular deserts allowed xerophilic species that had evolved with desert of the southwest United States to invade the Baja California peninsula. Thus, the evolution of the herpetofauna of Baja California is tied to both vicariant and dispersal events.
Ecological differences between two sympatric species of rattlesnake in Mission Trails Regional Park, San Diego County, California
William E. Haas
A five year study of northern red (Crotalus ruber ruber, CrRu) and southern Pacific (Crotalus viridis helleri, CrVi) rattlesnakes in Mission Trails Regional Park produced data indicating significant differences between species in habitat use, activity cycles, prey choice and hunting strategy. Data were obtained from more than 1200 marked individual rattlesnakes over the five year period. Crotalus v. helleri (CrVi) was found more commonly than C. r. ruber (CrRu) by a ratio of approximately 5:1 (988:242). Crotalus r. ruber (CrRu) was most frequently found in cooler, more shaded habitats while C. v. helleri (CrVi) was most often encountered on south facing slopes with more open vegetation types, especially Diegan Coastal Sage Scrub and Non-native Grassland. Their occurrence is not, however, mutually exclusive. Crotalus r. ruber (CrRu) is more sedentary and is more typically a "sit -and-wait" predator. Crotalus v. helleri (CrVi) is a more active hunter and shifts from a diurnal to nocturnal activity cycle during warm, dry months of the year. Limited data indicate both prey choice and prey size differs between the two species.
Thermoregulation in three species
of Phyllodactylus (Squamata: Gekkonidae)
Candy M. Hamp
The field of lizard thermobiology has disproportionately focused on diurnal lizards inhabiting hot, arid environments; negligible information is available regarding the thermoregulation of nocturnal species. And to date, no research has been done regarding the possible behavioral thermoregulation of Phyllodactylus. This study investigates the thermobiology of Phyllodactylus bugastroplepis, P. xanti, and P. unctus. Body (Tb), substrate (Ts), and air (Ta) temperatures were recorded at seven separate populations from both insular and mainland localities of Baja California, México. Data were then later subjected to Student t-tests for comparisons of mean Tb and Ts, confirming a statistical difference between them: P. bugastroplepis (P<3.256 x 10-3), P. unctus (P<2.604 x 10-6), and P. xanti (P<2.007 x 10-14). In addition, Tb and Ts from the collective populations also differ significantly (P<0.001) and show no intraspecific significant difference between localities. These high Tb of the Phyllodactylus studied here are presumably maintained by behavioral thermoregulation. The data explain that Phyllodactylus must obtain heat from a source other than the immediate substrate from which they were collected, undoubtedly using this energy for noctural foraging. Because rocks and various other dense substrate possess a high specific heat, I hypothesize that Tb are elevated by the lizards active utilization of the undersides of these objects, as they necessarily retain heat from the earlier daylight hours.
Venom expenditure during predatory bites by Crotaline snakes.
William K. Hayes
A series of experiments were conducted to learn how rattlesnakes (Crotalus viridis) use their venom during predatory strikes. Adult rattlesnakes release roughly one-third to one-quarter of their venom supplies in a single bite of a mouse; approximately 90% of the venom enters the prey tissues. The quantity of venom injected increases exponentially with size of snake. Hungry snakes inject less venom than well-fed snakes. Rattlesnakes attempt to inject more venom into sparrows and lizards than mice. They also attempt to deliver more into larger prey than smaller prey, apparently through intrinsic control of venom delivery under control of the central nervous system. Thus, rattlesnakes appear capable of selectively allocating or "metering" their venom supplies, releasing an amount appropriate for the target and context.
Salt gland secretion by an intertidal lizard, Uta tumidarostra.
Lisa C. Hazard
Uta tumidarostra is found in the rocky intertidal zone of a small island in the Gulf of California. The lizard has hypertrophied nasal salt glands and feeds primarily on intertidal isopods, which have high levels of sodium chloride. I measured field salt gland secretion by U. tumidarostra and the related insectivorous mainland species U. stansburiana. U. stansburiana secreted more potassium than chloride, as is typical for most lizards, while U. tumidarostra secreted about three times more sodium than potassium. U. tumidarostra secreted more sodium and potassium than did U. stansburiana. Based on measured ion, water, and energy contents of prey items and on published values for metabolic rate and other factors, we estimated the minimum amount of each ion that the salt gland of each species must excrete daily to maintain osmotic homeostasis. Uta stansburiana should be able to excrete all of the ions in a diet of insects via the kidneys, and probably cannot excrete ions rapidly enough to cope with the isopod diet. For U. tumidarostra, at most 55% of the estimated chloride intake can be excreted by the kidney, so the salt gland must account for at least 45% of chloride excretion and 37% of cation (sodium + potassium) secretion. The minimum estimated daily secretion rate is comparable to the measured average field secretion rate for U. tumidarostra. The hypertrophied salt gland apparently allows this species to use an abundant food source too salt for other lizards to eat in large quantity.
Venom expenditure during defensive bites by Crotaline snakes.
Shelton S. Herbert* and William K. Hayes
The purpose of this study was to measure the mass of venom expended by rattlesnakes (Crotalus viridis and C. atrox) and cottonmouths (Agkistrodon piscivorus) during defensive bites at models of human limbs (saline-filled latex/nitrile gloves). Defensive strikes were recorded by S-VHS video and subjected to slow-motion analysis. The mass of venom injected into gloves was determined by total protein assay (Bradford method). The rate at which venom is expelled from the fangs (mg/sec) was determined from venom extractions using videography and venom quantification. Other than occasional dry bites, rattlesnakes and cottonmouths expend considerably more venom when biting defensively than when feeding on mice. The amount of venom injected was proportional to body size of snake but independent of the duration of fang contact. Analysis of venom flow rates suggest that venom delivery during brief defensive bites (less than 0.1 sec fang contact) is constrained, resulting in reduced venom delivery.
The phylogeography of the colorado fringe-toed lizard
Bradford D. Hollingsworth* and Ronald L. Carter
Maribel R. Koury, L. Lee Grismer, and Humberto Wong
The phylogeography of Uma notata is analyzed using mitochondrial DNA in order to assess genetic relationships and assess current subspecies categories. Nine populations of U. n. notata and U. n. rufopunctata are included from Sonora, Baja California, and California. Approximately 1000 bp of DNA sequence data from the mitochondrial genes cytochrome b and cytochrome oxidase have been generated using an ABI Automated Flourescent Sequencer for each of these populations. A gene tree was constructed using parsimony methods and rooted with U. scoparia. Preliminary results indicate that southern populations in Sonora were found basally within the tree, while more northern populations in Califonria were nested high in the tree. This suggests a south to north migration after the cladogenic event which isolated U. scoparia to the north. Sequence data from the endangered U. inornata is necessary for the reanalysis of the data to determine if this species is nestedwithin the tree or located basally.
Geographic variation and environmental determinants of reproductive output in the desert tortoise
Three study sites were established in California in the spring of 1997 as part of a multi-year study to examine variation in reproductive output of desert tortoises: Joshua Tree National Park (JTREE), Mojave National Preserve (MOJAVE), and an area of land leased by the Bureau of Land Management (BLM) for wind energy production near Palm Springs (MESA). At MESA, 9 out of 10 monitored females produced a total of 72 eggs. Of these females, 6 produced second clutches and one produced a third clutch. Clutch size ranged from 2-8 eggs. Modal clutch size was 4 eggs. Mean clutch sizes were 4.33 and 5.00 eggs for first and second clutches, respectively. First clutch size was positively correlated with carapace length (R2=0.29) but not significantly (P=0.14). When all clutches were considered, a significantly positive relationship was detected (R2=0.26, P=0.04) The earliest date of egg laying occurred between April 18-23. The last clutch was oviposited sometime after July 3. At JTREE, only 1 of 8 females produced a single clutch 5 eggs). At MOJAVE, 12 of 18 monitored tortoises produced 43 eggs in single clutches with no subsequent clutches. Clutch size ranged from 1-7 eggs with modal clutch size of 3-4 eggs. Mean clutch size was.58 eggs. Larger females produced larger clutches and the between the two variables was almost significant (R2=0.32, P=0.055). Most of the variation observed appears to be to differences among sites in rainfall and associated of annual food plants.
Commercialization of reptiles from the Peninsula of Baja California and its associated islands.
L. Lee Grismer
The intense tectonic and ecologic transformations associated with the formation of the Peninsula of baja California have resulted in the evolution of many unique forms of reptiles on the peninsula itself and on its associated islands. Several of these forms have attracted reptile hobbyists and commercial breeders, and a market has developed. We have documented the marketing of 28 forms (including 9 variants of rossy boa, Lichanura trivirgata). Prices for adults range from $100 US Dlls for many species to $975 US Dll for a pair of Angel Island rattlesnakes (Crotalus mitchellii anglensis).
The capture of reptiles for the market has several negative environmental impacts on the habitat. These include, displacing rocks, prying and breaking rock cracks and removing exfoliations off large boulders, and spraying gasoline into rock cracks. These methods vary from a short term to a permanent impact on the habitat, and can impact insects, amphibians, reptiles, mammals, and plants.
No data exist to assess the impacts of collecting on the populations of the reptiles involved. Many of them have probabily not been impacted yet. However, species like the Todos Santos island mountain kingsnake (Lampropeltis zonata herrerae) could be already in trouble. This subspecies is restricted to a small island, to which cats have been introduced causing the extinction of one of kingsnake's potential food items, the endemic packrat. The kingsnake is killed by fishermen upon sight, because of anti-snake tabues. The accesibility of the island and the attraction that kingsnakes have, make this kingsnake is a common target for reptile collectors. The capture of this kingsnake, on top of the other factors, could easily jeopardize its continued existence.
Other insular forms, although normally common or abundant, may still face threats from collecting. The spiny chuckwalla (Sauromalus hispidus) is normally abundant on 11 islands in the Sea of Cortés, but its populations are subject to great fluctuations due to climatic factors. In addition, they now must withstand the effects of predators that have been introduced to many of the islands. Heavy collecting pressure during a population low could represent, at least, a genetic bottleneck for this species on some of the islands; in the worst case it could mean its extirpation from some of the islands.
Current mexican wildlife laws give some room for the commercial utilization of wildlife (former laws did not), but a specific permit must be obtained. We were unable to find any reference to a permit issued for commercial purposes, although a number of research permits have been issued. The later, however, preclude commercial use of the specimens. The mexican office in charge of preventing environmental offenses (Procuraduría de Protección al Ambiente) lacks the manpower and resources to adequately monitor the different areas and prevent the illegal capture of reptiles. Although US wildlife agents succesfully prosecuted 12 offenders in 1992, there appears to be much illegal introduction of mexican reptiles into the United States escaping detection. Given the former, awarness among reptile hobbyists seems the best way to reduce the ilegal take of mexican reptiles and its associated potential environmental impacts.
Arguments have been made that the captive propogation of Mexican reptiles is a hedge against their potential extinction. However, we believe this is more a deceptive ploy by commercial collectors and breeders. In fact, the high prices charged for many species occuring in Baja California and their accessiblity to collectors, has made them easy targets for illegal collection and has contributed to the destruction of much of their habitat.
Mitochondrial DNA phylogeography of the sand snakes Chilomeniscus (Serpentes: Colubridae) from northwestern México and southern Arizona
Humberto Wong*, L. Lee Grismer, and Bradford D. Hollingsworth
Ronald L. Carter
The sand snake genus Chilomeniscus consists of four species distributed across northwestern México and southern Arizona. Aside from the two insular endemic species (Chilomeniscus punctatissimus and C. savagei) from the southern Gulf of California, the wide-ranging banded C. cinctus and unbanded C. stramineus maintain allopatric populations on either side of the Gulf of California. These two species are currently recognized almost solely on the basis of color pattern characteristics (i.e., C. cinctus banded and C. stramineus unbanded). The clonal evolutionary history of maternally inherited mtDNA of Chilomeniscus is traced using a 380 bp fragment of the cytochrome b region. A gene tree constructed by parsimony analysis corresponds to a pectinate tree in which C. savagei is the most basal lineage and Sonoran Chilomeniscus are the most derived, which suggests a southern Baja California origin for the genus. Haplotypes of unbanded, banded, and intermediate specimens were sequenced as were those of the putative outgroup genera Chionactis, and Sonora. The placement of unbanded and banded specimens being more closely related to each other than to other unbanded and banded specimens on the gene tree suggests that C. cinctus and C. stramineus are color variants of one species. This evidence for polymorphism independently corroborates the morphological evidence I presented at the 1996 ASIH/HL meetings. Based upon these two independent sources, I recommend placing C. cinctus in the synonymy C. stramineus.