Teiidae Research Articles

Reproduction of a whiptail lizard (Ameivula ocellifera, Teiidae) from a coastal area in northeastern Brazil.

The reproductive ecology of Ameivula ocellifera was studied from September 2009 to August 2010 in a coastal area of the state of Ceará, Brazil. Females reproduced continuously throughout the year, with a peak at the end of the rainy season. Even though there was a predominance of pre-reproductive individuals in the sample, gonadal activity of males peaked synchronously to female reproduction. Mean clutch size was 1.98 ± 0.56 and positively associated with female body size, while mean egg volume was 510.54 ± 84.29 mm3 and unrelated to female body size. We did not find any association between clutch size and average egg volume.

Gastrointestinal Helminths from Eight Species ofAspidoscelis(Squamata: Teiidae) from Mexico

Seventy-four representatives of 8 species of whiptail lizards (Aspidoscelis ssp.), from Mexico were examined for helminths: Aspidoscelis calidipes (n = 8), A. communis (n = 10), A. cozumelae (n = 9), A. gularis (n = 10), A. lineattissima (n = 9), A. motaguae (n = 11), A. parvisocia (n = 9), and A. sackii (n = 8). We found one species of Cestoda, Oochoristica scelopori, and 7 species of Nematoda, including Abbreviata terrapenis, Parapharyngodon alvarengai, Pharyngodon warneri, Spauligodon garciaprietoi, Spinicauda spinicauda, Thubunaea cnemidophorus, and Physaloptera sp. Mean helminth diversity per lizard species was 3.1 (SD 1.8). Spauligodon garciaprietoi was present in 6 of 8 (75%) of the lizard species. The specimens we examined were infected by an aggregate of helminths that were either characteristic of Aspidoscelis spp. from the United States (North America: O. scelopori, T. cnemidophorus, A. terrapenis, P. warneri) or characteristic of Aspidoscelis spp. from Mexico (Mesoamerica: S. garciaprietoi, P. alvarengai, S. spinicauda). Twentytwo new host records are reported.

Whiptail lizards in South America: a new Ameivula (Squamata, Teiidae) from Planalto dos Gerais, Eastern Brazilian Cerrado

We describe a new species of whiptail lizard genusAmeivulafrom Planalto dos Gerais, a sandstone plateau that extends along the Cerrado region in the states of Bahia, Tocantins, Piauí, and Minas Gerais, in Brazil. The new species is the third recognized species of theA. ocelliferagroup registered for the Cerrado. Quantitative analyses of morphometric characters showed that Caatinga species are distinguished from their Cerrado congeners on basis of body size and shape. A discriminant analysis upon meristic characters showed that the new species can be clearly distinguished from the other two Cerrado speciesA. mumbucaandA. jalapensis, also the morphology of the finger lamellae, and clutch size distinguish these species.

Life history of the Marbled Whiptail Lizard Aspidoscelis marmorata from the central Chihuahuan Desert, Mexico

The life history of a population of marbled whiptail lizard, Aspidoscelis marmorata , was examined from 1989 to 1994 in the sand dunes of the Biosphere Reserve of Mapimi, in Northern Mexico. Lizards were studied using mark-recapture techniques. Reproduction in females occurred between May and August, with birth hatchlings matching the wet season in August. Reproductive activity was highest in the early wet season (July). Males and females reached adult size class at an average age of 1.7 years and 1.8 years, respectively. Body size of males attained an asymptote around 90 mm snout-vent length and females around 82 mm snout-vent length, at an age of approximately 3.6 years and 3.0 years, respectively. The density varied from 7 to 85 individuals / 1.0 ha. The Mexican population had late maturity, relatively long life expectancy, and fewer offspring. Overall, the observed data for A. marmorata and the expectations of life history theory for a late maturing species (K - rate selection) are in agreement.

Comparison of Diets of Two Syntopic Lizards,Aspidoscelis marmorataandAspidoscelis tesselata(Teiidae), from the Northern Chihuahuan Desert of Texas

Abstract We compared types and volume of prey in the diets of two whiptail lizards (Teiidae), Aspidoscelis marmorata (a bisexual species) and A. tesselata (a unisexual species) that occur syntopically in a Chihuahuan Desert landscape on Indio Mountains Research Station, Hudspeth County, Texas. Because their home ranges overlap extensively, we hypothesized that there would be dietary resource partitioning between the two species. Stomach contents of 69 A. marmorata and 21 A. tesselata included only arthropods. Aspidoscelis marmorata used 14 orders of arthropods for prey, while A. tesselata used eight orders. Isopterans (termites) were the principal food for both species by count (93.5 and 83.8% in male and female A. marmorata, respectively; 94.6% in A. tesselata). By volume, Homoptera (37.8 and 10.3%), Araneae (11.9 and 54.1%), Orthoptera (18.0 and 0.9%), and Isoptera (16.6 and 3.6%) composed 84.3 and 68.9% of the diet of male and female A. marmorata, respectively; whereas Orthoptera (29.8%), Homoptera (29...

Androgens coordinate neurotransmitter‐related gene expression in male whiptail lizards

Sex steroid hormones coordinate neurotransmitter systems in the male brain to facilitate sexual behavior. Although neurotransmitter release in the male brain has been well documented, little is known about how androgens orchestrate changes in gene expression of neurotransmitter receptors. We used male whiptail lizards (Cnemidophorus inornatus) to investigate how androgens alter neurotransmitter-related gene expression in brain regions involved in social decision making. We focused on three neurotransmitter systems involved in male-typical sexual behavior, including the N-methyl-d-aspartate (NMDA) glutamate receptor, nitric oxide and dopamine receptors. Here, we show that in androgen-treated males, there are coordinated changes in neurotransmitter-related gene expression. In androgen-implanted castrates compared with blank-implanted castrates (control group), we found associated increases in neuronal nitric oxide synthase gene expression in the nucleus accumbens (NAcc), preoptic area and ventromedial hypothalamus, a decrease of NR1 gene expression (obligate subunit of NMDA receptors) in the medial amygdaloid area and NAcc and a decrease in D1 and D2 dopamine receptor gene expression in the NAcc. Our results support and expand the current model of androgen-mediated gene expression changes of neurotransmitter-related systems that facilitate sexual behavior in males. This also suggests that the proposed evolutionarily ancient reward system that reinforces sexual behavior in amniote vertebrates extends to reptiles.

Feeding Habits and Predator-Prey Size Relationships in the Whiptail LizardCnemidophorus ocellifer(Teiidae) in the Semiarid Region of Brazil

We studied the diet of the whiptail lizard Cnemidophorus ocellifer (Spix, 1825) and the relationships between predator size and prey size in a Caatinga area of northeastern Brazil. Lizards (N = 111) were collected during the day through active search. In the laboratory, we measured them and registered the number of ingested items of each prey category to Order, as well as the dimensions and frequencies of each. The main prey category in the C. ocellifer diet was insect larvae and pupae, followed by Orthoptera, Isoptera, Coleoptera and Araneae. Termites (Isoptera) were important only in numeric terms, having negligible volumetric contribution and low frequency of occurrence, an uncommon feature among whiptail lizards. The types and sizes of prey consumed by adult males and females were similar, despite sexual dimorphism in head size. Adults and juveniles ingested similar prey types, but differed in prey size. Maximum and minimum prey sizes were positively correlated with lizard body size, suggesting that in this population individuals experience an ontogenetic change in diet, eating larger prey items while growing, and at the same time excluding smaller ones.

Courtship Behavior in the Cuban Ameiva (Ameiva auberi ustulata, Squamata: Teiidae) from the Siboney-Juticí Ecological Reserve in Eastern Cuba


 
 
 
 The genus Ameiva Meyer 1795 comprises 23 species of which 14 are found in Central and South America and 18 occur in the West Indies. These lizards occupy diverse habitats (e.g., grasslands, tropical forests, sandy beaches) but most species appear to prefer open areas. They are ground-dwellers and active diurnal foragers. Cuba harbors only one species, Ameiva auberi. However, 40 subspecies are distributed widely across the main island, adjacent cays, and on into the Bahamas. Reproductive behavior has been documanted in some species in the family Teiidae, but not for A. auberi, about which only one published account reported the underground deposition of a single egg. Herein, we describe for the first time the reproductive behavior (except ovipositioning) of A. auberi ustulata in natural habitat in the Ecological Reserve Siboney-Jutici (eastern Cuba) on 22-25 July 2009. Between 1200 and 1600 h, we observed six mating pairs directly or while using monocular Nikon Fieldscopes. We describe three sequential stages of reproductive behaviior: (1) Pursuit, (2) prematiing and mating, and (3) excavation, with a total duration of 64.8+-17.6 min (46-92 min).
 
 
 

Comparative Meristic Variability in Whiptail Lizards (Teiidae,Aspidoscelis): Samples of ParthenogeneticA. tesselataVersus Samples of Sexually ReproducingA. sexlineata, A. marmorata, andA. gularis septemvittata

ABSTRACT Is it correct, as is often assumed, that the clonal form of inheritance in parthenogenetic lizards results in less variability than occurs with genetic recombination in their sexually reproducing (gonochoristic) relatives? We tested this hypothesis by comparing morphological variability in samples of parthenogenetic Aspidoscelis tesselata and several gonochoristic species of whiptail lizards. To control for environmental factors that might differentially affect embryonic development of morphological characters, we compared samples obtained from the same or geographically adjacent localities. In addition, we compared apparently “uniclonal” and multiclonal samples from each of two color-pattern classes (C and E) of A. tesselata. For univariate meristic characters, parthenogenetic A. tesselata matched the variability of a sympatric gonochoristic species in 11 of 20 comparisons, had lower variability in six comparisons, and was more variable in three. For multivariate characters derived from principa...

Helminths of Cnemidophorus ruthveni (Squamata: Teiidae) from Bonaire, Netherlands Antilles, with Description of A New Species of Alaeuris (Nematoda: Pharyngodonidae)

Alaeuris rinconensis n. sp. (Oxyuroidea, Pharyngodonidae) from the large intestine of the Bonaire whiptail lizard, Cnemidophorus ruthveni, is described and illustrated. Alaeuris rinconensis n. sp. represents the 13th Neotropical species assigned to the genus. It is most similar to Alaeuris iguanae in that only these 2 Neotropical species have postbulbar excretory pores; in A. iguanae, a tail filament is absent; in A. rinconensis, a tail filament is present. Two additional helminth species were found, i.e., the cestode Oochoristica iguanae and a nematode, Ozolaimus megatyphlon. Cnemidoporus ruthveni represents a new host record for the latter 2 species.

Effects of grazing and invasive grasses on desert vertebrates in California

AbstractMuch of California's San Joaquin Valley is a desert and, like portions of other North American deserts, is experiencing an ecological shift from being dominated by ephemeral native forbs, with widely spaced shrubs, to fire‐prone non‐native annual grasses. Small terrestrial vertebrates, many of which are adapted to open desert habitats, are declining. One hypothesis is that the invasive plants contribute to the decline by altering vegetative structure. Although cattle may have originally been a factor in the establishment of these non‐native plants, their grazing may benefit the terrestrial vertebrates by maintaining an open structure, especially during average or wet winters when the exotic grasses grow especially dense. We experimentally tested the effect of cattle grazing on invasive plants and a community of small vertebrates at a site in the southwestern San Joaquin Desert. We established and monitored 4 treatment (grazed) and 4 control (ungrazed) plots from 1997 to 2006, and assessed the abundances of blunt‐nosed leopard lizards (Gambelia sila), giant kangaroo rats (Dipodomys ingens), short‐nosed kangaroo rats (Dipodomys nitratoides nitratoides), and San Joaquin antelope squirrels (Ammospermophilus nelsoni), all of which are listed as threatened or endangered by state or federal agencies. We also recorded abundances of the non‐protected western whiptail lizards (Aspidoscelis tigris), side‐blotched lizards (Uta stansburiana), San Joaquin pocket mice (Perognathus inornatus inornatus), and Heermann's kangaroo rats (Dipdomys heermanni). Based on repeated measures analysis of variance (ANOVA) and a 0.05 alpha level, only Heermann's kangaroo rats showed a treatment effect; they were more abundant on the control plots. However, this effect could be accounted for by the natural re‐establishment of saltbush (Atriplexspp.) on part of the study site. Saltbush return also favored western whiptail lizards and San Joaquin antelope squirrels. A regression analysis indicated that populations of blunt‐nosed leopard lizard and giant kangaroo rat increased significantly faster in grazed plots than the ungrazed controls, and abundances of 6 of 8 species were negatively correlated with increased residual dry matter. With relaxed alpha values to decrease Type II error, populations of blunt‐nosed leopard lizards (500% greater), San Joaquin antelope squirrels (85% greater), and short‐nosed kangaroo rats (73% greater) increased significantly on grazed plots over the course of the study compared to ungrazed plots. We did not find grazing to negatively affect abundance of any species we studied. When herbaceous cover is low during years of below average rainfall in deserts and other arid areas, grazing may not be necessary to maintain populations of small vertebrates. However, if cattle grazing is closely monitored in space and time to minimize adverse effects on the habitat, it could be an effective tool to control dense stands of non‐native grasses and benefit native wildlife. © 2011 The Wildlife Society.

Mating behavior and female accompaniment in the whiptail lizard Cnemidophorus ocellifer (Squamata, Teiidae) in the Caatinga region of northeastern Brazil

We report here a set of observations on mating behavior and female accompaniment by the whiptail lizard Cnemidophorus ocellifer in an area of Caatinga (xerophilous open forests) in the state of Rio Grande do Norte, northeastern Brazil. We observed a stationary male lizard performing repeated vibratory movements of the pelvis and tail base upon the sandy soil. Since that male was in front of a burrow in which a female of the same species was sheltered, we hypothesize that this behavior may be part of a courtship display. We continued the observation and later, when the female emerged from the burrow, the male climbed on her and the copulation occurred. The incident of accompaniment observed was characterized by one male continuously accompanying a female during foraging. Plausible functional explanations for a male accompany a female include mating guarding, post-copulatory courtship, and sperm loading. By accompanying females, males would be guaranteeing insemination by multiple copulation and stimulation of the female, and protecting their paternity by chasing away other males, diminishing the chances of extra-pair copulations.

Chemical Constituents of the Femoral Gland Secretions of Male Tegu Lizards (Tupinambis merianae) (Family Teiidae)

In spite of the importance of chemical signals (pheromones) in the reproductive behaviour of lizards, the chemical compounds secreted by their femoral glands, which may be used as sexual signals, are only known for a few lizard species. Based on mass spectra, obtained by GC-MS, we found 49 lipophilic compounds in femoral gland secretions of male tegu lizards (Tupinambis merianae) (fam. Teiidae), including a very high proportion of carboxylic acids and their esters ranging between n-C8 and n-C20 (mainly octadecanoic and 9,12-octadecadienoic acids), with much less proportions of steroids, tocopherol, aldehydes, and squalene. We discuss the potential function of these compounds in secretions, and compare the compounds found here with those documented for other lizard species.

Locomotor loading mechanics in the hindlimbs of tegu lizards (Tupinambis merianae): comparative and evolutionary implications

Skeletal elements are usually able to withstand several times their usual load before they yield, and this ratio is known as the bone's safety factor. Limited studies on amphibians and non-avian reptiles have shown that they have much higher limb bone safety factors than birds and mammals. It has been hypothesized that this difference is related to the difference in posture between upright birds and mammals and sprawling ectotherms; however, limb bone loading data from a wider range of sprawling species are needed in order to determine whether the higher safety factors seen in amphibians and non-avian reptiles are ancestral or derived conditions. Tegus (family Teiidae) are an ideal lineage with which to expand sampling of limb bone loading mechanics for sprawling taxa, particularly for lizards, because they are from a different clade than previously sampled iguanas and exhibit different foraging and locomotor habits (actively foraging carnivore versus burst-activity herbivore). We evaluated the mechanics of locomotor loading for the femur of the Argentine black and white tegu (Tupinambus merianae) using three-dimensional measurements of the ground reaction force and hindlimb kinematics, in vivo bone strains and femoral mechanical properties. Peak bending stresses experienced by the femur were low (tensile: 10.4 ± 1.1 MPa; compressive: -17.4 ± 0.9 MPa) and comparable to those in other reptiles, with moderate shear stresses and strains also present. Analyses of peak femoral stresses and strains led to estimated safety factor ranges of 8.8-18.6 in bending and 7.8-17.5 in torsion, both substantially higher than typical for birds and mammals but similar to other sprawling tetrapods. These results broaden the range of reptilian and amphibian taxa in which high femoral safety factors have been evaluated and further indicate a trend for the independent evolution of lower limb bone safety factors in endothermic taxa.

Laboratory synthesis of an independently reproducing vertebrate species

Speciation in animals commonly involves an extrinsic barrier to genetic exchange followed by the accumulation of sufficient genetic variation to impede subsequent productive interbreeding. All-female species of whiptail lizards, which originated by interspecific hybridization between sexual progenitors, are an exception to this rule. Here, the arising species instantaneously acquires a novel genotype combining distinctive alleles from two different species, and reproduction by parthenogenesis constitutes an effective intrinsic barrier to genetic exchange. Fertilization of diploid parthenogenetic females by males of sexual species has produced several triploid species, but these instantaneous speciation events have neither been observed in nature nor have they been reconstituted in the laboratory. Here we report the generation of four self-sustaining clonal lineages of a tetraploid species resulting from fertilization of triploid oocytes from a parthenogenetic Aspidoscelis exsanguis with haploid sperm from Aspidoscelis inornata. Molecular and cytological analysis confirmed the genetic identity of the hybrids and revealed that the females retain the capability of parthenogenetic reproduction characteristic of their triploid mothers. The tetraploid females have established self-perpetuating clonal lineages which are now in the third generation. Our results confirm the hypothesis that secondary hybridization events can lead to asexual lineages of increased ploidy when favorable combinations of parental genomes are assembled. We anticipate that these animals will be a critical tool in understanding the mechanisms underlying the origin and subsequent evolution of asexual amniotes.

Natural History Observations of the Ichthyological and Herpetological Fauna on the Island of Curaçao (Netherlands)

Despite increasing popularity of the island as an ecotourist destination, the ecology and natural history of many organisms native to the Lesser Antillean island of Curaçao have remained enigmatic. We document multiple new observations of the behavioral ecology of several terrestrial and aquatic vertebrates that inhabit Curaçao. We present the first report of avian predation on the endemic Curaçao whiptail lizard, Cnemidophorus murinus, suggesting these lizards play a potentially important role in this island's food web. We also document the first instance of predation by the introduced tropical house gecko. Hemidactylus mabouia, on the native Antilles gecko, Gonatodes antillensis. Tropical house geckos are thought to be displacing native geckos through a combination of niche displacement and competitive exclusion, and our finding suggests that predation on smaller native lizards may be another factor aiding the success of this introduced gecko on Curaçao. We also present repeated observational evidence that juvenile bluehead wrasses (Thalassoma bifasciatum) seek refuge among the sessile and venomous giant Caribbean sea anemones (Condylactis gigantean).

Neuronal Nitric Oxide Synthase as a Substrate for the Evolution of Pseudosexual Behaviour in a Parthenogenetic Whiptail Lizard

The evolution of neuroendocrine mechanisms governing sex-typical behaviour is poorly understood. An outstanding animal model is the whiptail lizard (Cnemidophorus) because both the ancestral and descendent species still exist. The ancestral little striped whiptail, Cnemidophorus inornatus, consists of males and females, which exhibit sex-specific mating behaviours. The descendent desert grassland whiptail, Cnemidophorus uniparens, consists only of females that alternately exhibit both female-like and male-like pseudosexual behaviour. Castrated male C. inornatus will mount a conspecific in response to exogenous androgen, although some are also sensitive to progesterone. This polymorphism in progesterone sensitivity in the ancestral species may have been involved in evolution of progesterone-mediated male-typical behaviour in the descendant unisexual lizards. We tested whether progesterone activates a typically androgenic signalling pathway by investigating hormonal regulation of neuronal nitric oxide synthase (nNOS) using in situ hybridisation and NADPH diaphorase histochemistry, a stain for nNOS protein. NADPH diaphorase is widely distributed throughout the brain of both species, although only in the periventricular nucleus of the preoptic area (pvPOA) are there differences between mounting and non-mounting individuals. The number of cells expressing nNOS mRNA and NADPH diaphorase is higher in the pvPOA of individuals that mount in response to progesterone or androgen. Furthermore, the nNOS promoter has both androgen and progesterone response elements, and NADPH diaphorase colocalises with the progesterone receptor in the pvPOA. These data suggest that a polymorphism in progesterone sensitivity in the sexual ancestor reflects a differential regulation of nNOS and may account for the male-typical behaviour in unisexual whiptail lizards.

Living in a caatinga-rocky field transitional habitat: ecological aspects of the whiptail lizard Cnemidophorus ocellifer (Teiidae) in northeastern Brazil

The ecology of the active forager lizard Cnemidophorus ocellifer (Spix, 1825) was studied to analyze food habits, thermal ecology and habitat use, in the Morro do Chapéu municipality (11º29'S, 41º07'W), state of Bahia, Brazil. Lizards (N = 34) were collected with rubber bands or with an air rifle and, for each individual, we recorded cloacal temperature (Tc), air temperature (Ta) (1 cm above the substrate) and substrate temperature (Ts) (to nearest 0.2ºC). We registered the microhabitat used by each animal at the moment of first sight and measured its morphological variables (nearest 0.1 mm). In the laboratory, we registered the number of items of each prey category to the taxonomic level of Order, its dimensions and frequencies. Data showed that, numerically, the category most consumed was Isoptera (84.4%). Volumetrically, the diet was composed predominantly by Orthoptera (27.5%) and Isoptera (21.5%). Prey items that occur aggregated in the environment (termites) were important in the diet of C. ocellifer, a characteristic of active foragers. Males and females did not differ in the types of prey consumed. Cnemidophorus ocellifer had a mean Tc in activity of 37.6 ± 1.6ºC and the relationship between Tc and ambient temperatures (Ts and Ta) was positive and significant (F2,28 = 4.814; R² = 0.256; p < 0.05). Most lizards were first sighted on leaf litter inside shrubs (45.5%) and on leaf litter at shrub edge (42.4%). Cnemidophorus ocellifer had a relatively high mean Tc during activity, with Ts explaining most of the variation in lizard Tc.

Chemical Constituents of the Femoral Gland Secretions of Male Tegu Lizards (Tupinambis merianae) (Family Teiidae)

Chemical Constituents of the Femoral Gland Secretions of Male Tegu Lizards (Tupinambis merianae) (Family Teiidae)

Molecular characterization and brain distribution of the progesterone receptor in whiptail lizards

Progesterone and its nuclear receptor are critical in modulating reproductive physiology and behavior in female and male vertebrates. Whiptail lizards (genus Cnemidophorus) are an excellent model system in which to study the evolution of sexual behavior, as both the ancestral and descendent species exist. Male-typical sexual behavior is mediated by progesterone in both the ancestral species and the descendant all-female species, although the molecular characterization and distribution of the progesterone receptor protein throughout the reptilian brain is not well understood. To better understand the gene targets and ligand binding properties of the progesterone receptor in whiptails, we cloned the promoter and coding sequence of the progesterone receptor and analyzed the predicted protein structure. We next determined the distribution of the progesterone receptor protein and mRNA throughout the brain of Cnemidophorus inornatus and Cnemidophorus uniparens by immunohistochemistry and in situ hybridization. We found the progesterone receptor to be present in many brain regions known to regulate social behavior and processing of stimulus salience across many vertebrates, including the ventral tegmental area, amygdala, nucleus accumbens and several hypothalamic nuclei. Additionally, we quantified immunoreactive cells in the preoptic area and ventromedial hypothalamus in females of both species and males of the ancestral species. We found differences between both species and across ovarian states. Our results significantly extend our understanding of progesterone modulation in the reptilian brain and support the important role of the nuclear progesterone receptor in modulating sexual behavior in reptiles and across vertebrates.