Species Of Sceloporus Research Articles

Voluntary exposure of some western‐hemisphere snake and lizard species to ultraviolet‐B radiation in the field: how much ultraviolet‐B should a lizard or snake receive in captivity?

Studies of voluntary exposure to ultraviolet-B (UVB) radiation from the sun in the field were conducted in the southern US and Jamaica for 15 species of lizards and snakes occupying various habitats. Species were sorted into four zones of UVB exposure ranging from a median UV index of 0.35 for zone 1 to 3.1 for zone 4. Guidelines for UVB exposure in captivity of these and species occupying similar light environments are presented. Data for most species were collected during mid-day during the spring breeding season, which appeared to be the time of maximum exposure. For two species of Sceloporus studied more intensively there was significant variation of exposure among times of the day and among seasons. So, all-day studies over the entire active season are necessary to fully understand the pattern of natural exposure for a particular diurnal species. Environmental and body temperature and thermoregulation as well as UVB/vitamin D photoregulation influences exposure to UVB. Regressions allowing the inter-conversion of readings among some meters with different detector sensitivities are presented. Readings of natural sunlight predict the same photobiosynthetic potential for vitamin D as the same reading from artificial sources whose wavelength distribution within the UVB band of the source is comparable to that of sunlight. Research approaches to further increase our understanding of vitamin D and UVB use and requirements for squamate reptiles in captivity are outlined.

GENETIC RELATIONSHIPS AMONG POPULATIONS OF SCELOPORUS UNDULATUS FAIL TO SUPPORT PRESENT SUBSPECIFIC DESIGNATIONS

The eastern fence lizard, Sceloporus undulatus, is a broadly distributed polytypic species. We surveyed allozyme variation with the goal of generating an intraspecific phylogeny to evaluate the current classification of the species. We electrophoretically assayed 24 loci from 12 populations of S. undulatus, which comprised 6 of the 11 recognized subspecies, 3 additional species of Sceloporus (S. occidentalis, S. virgatus, and S. woodi), and an outgroup taxon, S. clarki. Out of the 24 loci, 14 loci were variable. Phylogenetic analyses using distance, likelihood, and parsimony resulted in trees that were inconsistent with current subspecific designations. Three species of Sceloporus (S. occidentalis, S. virgatus, and S. woodi) arose within S. undulatus. Two major lineages of populations of S. undulatus were identified: (1) a midwestern grasslands group that includes the population from Missouri, and (2) various populations from the eastern woodlands and western canyonlands. The subspecies S. u. hyacithinus ...

Phylogenetic Relationships among Phrynosomatid Lizards as Inferred from Mitochondrial Ribosomal DNA Sequences: Substitutional Bias and Information Content of Transitions Relative to Transversions

The phylogenetic relationships among 40 species, representing all genera, within the North American liz ard family Phrynosomatidae were inferred from mitochondrial ribosomal RNA gene sequences. Cladistic analysis of the DNA sequence data (779 bp; 162 informative characters) supported the monophyly of the sand lizards ( Callisaurus, Cophosaurus, Holbrookia, and Uma), Petrosaurus, Phrynosoma, Urosaurus, and Uta. Ah the species of Sceloporus, except S. variabilis and S. chrysostictus, formed a clade. Except for a sand lizard + Phrynosoma clade, the intergeneric relationships inferred from the mtDNA were largely incongruent with recent cladistic analyses based on morphology. Sceloporus group monophyly was not supported, with Petrosaurus being a member of a clade containing Sator, Sceloporus, and Urosaurus, to the exclusion of Uta. The phylogenetic placement of Uta was ambiguous. The substitutional bias in the phrynosomatid mitochondrial rDNA sequences was examined, as well as the phylogenetic information content of transitions relative to transversions. There appeared to be a lower transition bias than observed in other vertebrate sequences, with some classes of transversions occurring as frequently as G<->A transitions. Transitions were no less informative for phylogeny reconstruction than transversions. Therefore, transitions should not be down-weighted in phylogenetic analysis, as is often done.

Evolution and Phylogenetic Significance of Ribosomal Gene Location in Chromosomes of Squamate Reptiles

Using in situ hybridization with a biotin-labeled probe, we determined the chromosomal location of ribosomal genes in 56 species of squamate reptiles, including representatives of nine major taxa. Where possible, these data were examined in a phylogenetic context, and in several cases they provided phylogenetically useful shared derived character states. The ribosomal genes in Sceloporus variabilis are found on a single pair of microchromosomes, which seems to be primitive for the phrynosomatids. In the remainder of species of Sceloporus we examined, the ribosomal genes are found on the long arm of pair 2. We also found that Holbrookia, Cophosaurus, and Callisaurus share a derived condition not found in Uma. Two species of the viperid genus Agkistrodon share a condition that may be derived relative to other pit vipers. A third species of Agkistrodon differs from all other reptiles we examined in that ribosomal genes are located on the sex chromosomes. Location of rDNA also provides systematic information in several other clades of squamates.

Embryonic Development Times and Egg Retention in Four Species of Sceloporine Lizards

To test the hypothesis that rapid embryogenesis is an adaptation to cold climate, embryonic development time was measured in three oviparous species of Sceloporus that occur at different altitudes: S. woodi (lowland), S. virgatus (intermediate) and S. scalaris (high altitude). 2. Total embryonic development time (TEDT), defined as the time between ovulation to hatching, was measured at the same constant temperature (30°C) in the laboratory. Mean TEDT was 61*6 days in S. woodi, 55*3 days in S. virgatus, and 45.6 days in S. scalaris. Embryo stages at oviposition, which provide a qualitative assessment of egg retention time, were noted for females ovipositing in laboratory aquaria. S. woodi exhibited brief egg retention, S. virgatus, intermediate egg retention, and S. scalaris, prolonged egg retention

Synaptonemal Complex Analysis of Sex Chromosomes in Two Species of Sceloporus

Silver-stained synaptonemal complexes were analyzed to examine chromosomal pairing in two species of Sceloporus (S. graciosus and S. undulatus) that have indistinct sex chromosomes. Electron microscopic analyses revealed distinct length heteromorphism between the lateral elements of one of the largest microchromosomal synaptonemal complexes in each species. The morphology and behavior of the heteromorphic synaptonemal complex in S. graciosus and S. undulatus were congruous with those described for heteromorphic sex bivalents in other vertebrates and are hypothesized to represent synapsis of the sex chromosomes. Synaptic behavior of the heteromorphic bivalents was similar between species and differed from that of the homomorphic (autosomal) bivalents within each species. In both species, synapsis of the heteromorphic bivalent was characterized by the formation of a buckle in the synaptonemal complex at early to mid-pachynema. Synaptic adjustment was observed to result in equalization in length of the lateral elements.

Comparison of Population Structure in Chromosomally Polytypic and Monotypic Species of Sceloporus (Sauria: Iguanidae) in Relation to Chromosomally- Mediated Speciation

Comparison of Population Structure in Chromosomally Polytypic and Monotypic Species of Sceloporus (Sauria: Iguanidae) in Relation to Chromosomally- Mediated Speciation

Food partitioning and community organization in a mountain lizard guild of Northern Mexico.

Food niche relationships among four sympatric Sceloporus species were studied in the Sierra Madre Occidental, N.E. Mexico. Although some very high food-niche overlap values were observed, this does not prove that interspecific competition is currently important in organizing this lizard assemblage. Moreover, explaining habitat segregation among the coexisting species as an ecological result of interspecific competitive pressure is unlikely: the overall ecology and behaviour of these species is too much dependent on their microhabitat or substrate specialization to allow such an exclusive interpretation. Thus, this community is probably not mainly organized by species interactions but rather through the specific ecological needs of each species.

Close Relationship between the Lizard Genus Sator and Sceloporus utiformis (Reptilia, Lacertilia, Iguanidae): Electrophoretic and Immunological Evidence

Horizontal starch gel electrophoresis was employed in analysis of lactic dehydrogenase isozymes for two species of Sator, 22 species of Sceloporus, and representatives of all other sceloporine genera. Sator was compared electrophoretically to 12 species of Sceloporus for six additional presumptive gene loci. Albumin of Sator was compared immunologically to 38 species of Sceloporus and representatives of all other sceloporine genera. The findings indicate a close genetic relationship between the two insular species of Sator and the mainland Mexican Sceloporus utiformis. * * * The lizard genus Sator is comprised of two species restricted to three islands in the Gulf of California: Sator grandaevus on Cerralvo, and Sator angustus on Santa Cruz and San Diego islands. Sator is the only recognized endemic genus of terrestrial vertebrates restricted to the Gulf of California islands. Clarification of its phylogenetic relationships is important to furthering our understanding of the historical and ecological biogeography of the Baja California peninsula and its associated islands. Its present distribution suggests that it is a relict, and there are strong implications of competitive exclusion. On the three islands where it occurs, Uta, Urosaurus, and Sceloporus are all absent, although at least one member of these three genera occurs on virtually all other Gulf islands (Soule and Sloan, 1966). Since the description of Sator by Dickerson (1919), the taxonomic and biogeographic status of this genus has aroused interest. Dickerson believed that the affinities of Sator were with mainland Mexican Sceloporus of the utiformis group. Subsequent analyses of the relationships of Sator have dealt with morphological characters (Etheridge, 1962, 1964; Larsen and Tanner, 1975; Mittleman, 1942; Savage, 1958). This study provides additional evidence based upon independent sets of characters, electrophoretic mobilities of proteins and immuno- logical distances of serum albumins.

Thermoregulatory aspects of behavior in the blue spiny lizard Sceloporus cyanogenys (Sauria, Iguanidae).

Abstract1. The thermal relations of blue spiny lizards, Sceloporus cyanogenys, were studied in laboratory habitats which were designed to allow the expression of a large repertoire of natural behavior patterns. Body temperatures obtained with fast-reading thermometers and by radio telemetry from implanted transmitters were correlated with postures and activities. 2. The morning emergence of lizards was found to be cued by light, often in the absence of immediate thermal reinforcement. 3. Two basking postures which altered a lizard's air and substrate thermal interfaces could be distinguished. The environmental and body temperature correlates of these postures were not appreciably different, and the change from one posture to another could not be interpreted as thermoregulatory. 4. When thermal conditions permitted, basking continued up to the attainment of the maximum voluntary body temperature (38.7 C), and was then followed by perching. 5. The body temperature correlates of perching had a range and mean much like the "normal activity range" of other species of Sceloporus (28.2-38.7 C, X= 35.2). 6. Defecation occurred mostly in the morning towards the end of the basking period, but had a broad thermal range (27.5 to 35.7 C). 7. The range of body temperatures during feeding was broad (25.3-38.5 C), but that of foraging was much narrower (34.3-38.7 C).

The Diel Activity Cycle of the Lizard, Xantusia henshawi

? 1970. Temperature acclimation in two species of Sceloporus. Herpetologica 26:83-85. PAPPENHEIMER, J. R. 1950. Standardization of definitions and symbols in respiratory physiology. Fed. Proc. 9:602-605. REGAL, P. J. 1966. Thermophilic response following feeding in certain reptiles. Copeia 1966:588-590. SEYMOUR, R. S. 1973. Physiological correlates of forced activity and burrowing in the spadefoot toad, Scaphiopus hammondii. Copeia 1973:103-115. SPRAY, D. C., AND D. B. BELKIN. 1973. Thermal patterns in the heating and cooling of Iguana iguana and Ctenosaura hemophila. Comp. Biochem. Physiol. 44A:881-892. STEBBINS, R. C. 1958. An experimental study of the third eye of the tuatara. Copeia 1958: 183-190. TUCKER, V. A. 1966. Oxygen transport by the circulatory system of the green iguana (Iguana iguana) at different body temperatures. J. Exp. Biol. 44:77-92. 1967. The role of the cardiovascular system in oxygen transport and thermoregulation in lizards, p. 258-269. In: Lizard ecology: A symposium. W. W. Milstead (ed.). Univ. of Missouri Press, Columbia. VERON, J., AND H. HEATWOLE. 1970. Temperature relations of the water skink Sphenomorphus quoyi. J. Herpetol. 4:141-153. at re accli ation in two WARBURG, M. R. 1965. The influence of ambient temperature on the body temperature and water loss from two Australian lizards, Tiliqua rugosa (Gray) (Scincidae) and Amphibolurus barbatus Cuvier (Agamidae). Aust. J. Zool. 13:331-350. WEBB, G. J. W., C. R. JOHNSON AND B. T. FIRTH. 1972. Head body temperature differences in lizards. Physiol. Zool. 45:130-142. WILSON, K. J. 1971. The relationships of activity, energy metabolism, and body temperature in four species of lizards. Unpublished Ph.D. Thesis, Monash Univ., Clayton, Victoria. , AND A. K. LEE. 1970. Changes in the oxygen consumption and heart rate with activity and body temperature in the tuatara, Sphenodon punctatum. Comp. Biochem. Physiol. 33:311-322. , AND . Energy expenditure of a herbivorous lizard. Copeia (In press). WOOD, S. C., AND W. R. MOBERLY. 1970. The influence of temperature on the respiratory properties of iguana blood. Resp. Physiol. 10:20-29.

Another Cryptic Associate of the Lizard Sceloporus formosus in Guerrero, Mexico

Sceloporus adleri, a new species founded on 41 specimens, is related to the geographically adjacent species S. formosus, and is presumably limited to the Sierra Madre del Sur, Guerrero, Mexico. This Sierra appears to possess sufficient biotic endemism to justify recognition as a distinctive biotic province. Among specimens secured in Guerrero, Mexico, by Kraig Adler and his group during the winter of 1969, are 12 of a remarkably colorful species of Sceloporus cryptically related to S. formosus Wiegmann. Several other specimens of the same species had been secured by Adler earlier in the same area, and an additional series was secured for us in 1972 by David M. Dennis. We name this population Sceloporus adleri sp. nov. Holotype.-University of Michigan Museum of Zoology (UMMZ) 131689, a male, taken at Asoleadero, Guerrero, Mexico, 2520 m, on 17 December 1969, by Kraig Adler, David M. Dennis and David H. Snyder. Field no. MN 4466. Paratypes.-Forty, all from Guerrero, including UMMZ 126282 (5, field nos. IJ 1522-6), Cerro Teotepec (ca. 125 km by road W Xochipala), 3300-3400 m., 10 August 1964, Theodore J. Cohn and Jean Cohn; UMMZ 130134 (6, field nos. GH 9264-7, 9270-1), between Puerto Chico and Asoleadero, 2550-2600 m, 13-14 June 1964, Kraig Adler, Guy G. Musser and James H. Brown; Colorado University Museum (CUM) 50651-3, 5 km E Escalerillo, 2460 m, 20 December 1972, David M. Dennis, David H. Snyder, Mike Silvey, Don F. Harker; Field Museum of Natural History 191335-6, U.S. National Museum (USNM) 193236, University of Illinois Museum of Natural History 93532, all topoparatypes, 16 December 1969; Kansas University Museum of Natural History (KUMNH) 143612, CUM 46010, Museum of Comparative Zoology (MCZ) 129779, Brigham Young Univ. Mus. 40188, American Museum of Natural History (AMNH) 108211, California Academy of Science 133089, all topoparatypes, 17 December 1969; British Museum (Natural History) 1971.1856, ca. 3km (by road) E Puerto Gallo, 2740 m, 19 December 1969; CUM 50636-50, 2415 m; all topoparatypes, 19 December 1972, David M. Dennis, David H. Snyder, Mike Silvey, Don F. Harker. Twenty (USNM, KUMNH, CUM 46010, 50639-42, 50644, 50646-7, 50649, 50652, MCZ, AMNH, UMMZ field nos. 1522-3, 1526, 9264-5, 9270) are males; all others (20) are females. Collectors are Kraig Adler, David M. Dennis and David H. Snyder, unless otherwise noted. Definition.-A Sceloporus of the formosus group, distinguished from other members by the following combination of characters: mean dorsal scales 38.4; mean ventral scales 49.4; mean scales around midbody 43.7; mean femoral pores 13.3; mean scales between femoral pore series 12.8; median frontonasal in contact with lateral frontonasals; supraoculars generally not distinctly wider than long and generally not in contact with median head scales; scales on posterior surface of thigh relatively small; an incomplete, posteriorly light-bordered black nuchal collar; a pair of dorsolateral light stripes (obscure in large males); tan to dark brown dorsally in *Present address: Museum of Natural History, University of Kansas, Lawrence, Kansas 66045, USA.

A Preliminary Survey of Dermatoglyphic Variation in the Lizard Genus Sceloporus

Scanning electron microscopy of the outer surface of midlateral scales of 51 species of Sceloporus (%3/4 of those now known), representing all 15 groups (as of Smith, 1939) of the genus, suggests that dermatoglyphics are of no apparent diagnostic value at higher taxonomic levels in the genus Sceloporus, but may be very useful at the subspecies, species and species-group levels. Microornamentation of scale surfaces is seemingly unidirectional in evolution. Three variables are useful in systematic considerations in Sceloporus: degree of concavity of Oberhautchen cell surfaces, degree of overlap of cell boundaries, and degree of loss of spinules and reduction of surface pits; cristae occur in those species with the greatest cell-surface cavitation. All species examined exhibit Oberhautchen cell boundaries, much the same in size and shape. Dense spinulation, flat cell surfaces and lack of imbrication are primitive character-states in Sceloporus. * ** Most of the recent contributions to the rapidly-growing body of literature on the squamate integument centers upon the morphology of the ecdysis cycle (summarized by Maderson et al., 1972) and the range of dermatoglyphic variation as revealed by scanning electron microscopy (SEM) of scattered samples from lizards and snakes (summarized by Stewart and Daniel, 1973). No attempt has hitherto been made to explore the systematic significance of dermatoglyphic (DG) variation in either a broad (higher category) or narrow (intrageneric) perspective. Because of the long-standing interest of one of us in the systematics of Sceloporus (e.g., Smith, 1939), and the current explosion of investigation in that topic, we have attempted a survey of variation among the some 70 species now recognized in this genus

HYBRIDIZATION OF KARYOTYPICALLY DIFFERENTIATED POPULATIONS IN THE SCELOPORUS GRAMMICUS COMPLEX (IGUANIDAE).

Among the approximately 60 species of the lizard genus Sceloporus, there is much karyotypic diversity, resulting primarily from the fixation of rearrangements (centric fusions and fissions; Hsu and Mead, 1969; Jackson, 1971). Diploid (2n) chromosome numbers vary from 22 to 46 (Cole, 1970, 1971; Hall, 1973), a range exceeding that known for any other lizard genus. Because comparable variation has been detected in several groups of vertebrates, including other lizard genera (Gorman and Atkins, 1968; Matthey and van Brink, 1960) and rodents (review by Nadler, 1969), and in many invertebrates, evolutionists are becoming increasingly concerned with the role of karyotypic changes in animal speciation (White, 1969; Mayr, 1969, 1970). To investigate relationships between karyotypic diversification and speciation, Hall has undertaken a survey of chromosomal variation in Sceloporus and related genera, seeking particularly to identify intermediate evolutionary stages. Of 48 species of Sceloporus examined, all but one, the Mexican form S. grammicus, are karyotypically monomorphic, at least for Robertsonian mutations of the autosomes. An analysis of 1200 individuals of S. grammicus has revealed extensive chromosomal diversity at several levels of population structure, including the occurrence of rare individual variants, polymorphism, and the fixation of different Robertsonian modifications in parapatrically or allopatrically distributed populations. Chromosome numbers vary

Comparative Demography of Two Viviparous Iguanid Lizards (Sceloporus Jarrovi and Sceloporus Poinsetti)

Population studies of Sceloporus jarrovi using mark—recapture procedures were conducted on two study plots near Portal, Chiricahua Mountains, Cochise Co., Arizona during the summer months of 1969 and 1970. Similar studies of Sceloporus poinsetti were conducted on a study plot near Mertzon, Irion Co., Texas during the summer months of 1968, 1969, and 1970. Series of these lizards were taken from areas near the study plots and autopsied to determine their reproductive condition. The reproductive cycle of both species involved mating in the fall, with parturition occurring the following June. A single litter was produced each year. S. poinsetti attained maturity during the second mating season after birth, at about 16—17 months, although approximately 60% of the S. jarrovi females matured in their first mating season at about 5 months. Female S. jarrovi which matured as yearlings produced an average of four young in their 1st year, whereas older females produced an average of 10.5 young (7—15). The increase in litter size with snout—vent length was one embryo per 3 mm of body length. S. poinsetti females produced an average of 10.4 young (6—23) with an increase of one embryo per 3 mm of body length. Body sizes of young at birth were 29—35 mm in S. poinsetti and 25—32 mm in S. jarrovi. Newborn of both species were larger than hatchlings of similar sized oviparous species of Sceloporus. Newborn of S. poinsetti from large litters were significantly smaller than newborn from small litters. Populations of both S. jarrovi and S. poinsetti had 50:50 sex ratios. In June, the ratio of yearlings to older animals was approximately 50:50 in S. poinsetti and 60:40 in S. jarrovi. Of the eggs ovulated, 4.5% died before parturition in both species. Percent annual mortalities of S. poinsetti and S. jarrovi were respectively 86% and 81% (newborn), 54% and 56% (yearlings), and 57% and 63% (adults). The life history strategy of S. poinsetti appears to be relatively K—selected. S. jarrovi is more r—selected than S. poinsetti but more K—selected than most oviparous species.

Skeletal Adaptations in Two Species of Sceloporus

Skeletal Adaptations in Two Species of Sceloporus

Absence of One Eye in a Frog

All of the above specimens were captured alive. Had we been provided with a collecting pistol, we might have collected many more specimens of the two small species of Sceloporus and Holbrookia texana. The Marnock hill is very rocky and in many places is covered by growths of cedar, scrubby deciduous trees and shrubs, opuntias, and other flora. A number of goats get most of their subsistence on its slopes and summit and it is surprising that it is still inhabited by so many species of small native animals. In the sheep regions in western Texas, the wooly grazers have destroyed much of the smaller fauna through retarding the growth of vegetation, and killing snails and reptiles with their hoofs. Along Helotes Creek, I have at different times collected or noticed specimens of Eumeces brevilineatus Cope, Sceloporus spinosus floridanius Baird, Leiolepisma laterale Say, Cnemidophorus sexlineatus gularis Baird and Girard, Natrix sipedon transversa Hallowell, Natrix rhombifera Hallowell, Storeria dekayi Holbrook, Thamnophis proximus Say, Pseudacris ornata Holbrook, Acris gryllus Le Conte, Rana catesbeiana Shaw, R. pipiens Schreber, at least two large species of Bufo, and other species which I do not now recall. Water turtles are numerous in the creek. Considering the nearness of the large and populous city of San Antonio, the fauna of the Helotes neighborhood, as regards number of species, seems singularly undisturbed by the flight of the past forty years. BAYLOR UNIVERSITY, WACO, TEXAS.