David Lazcano

A multilocus perspective on the speciation history of a North American aridland toad (Anaxyrus punctatus).

Interpretations of phylogeographic patterns can change when analyses shift from single gene-tree to multilocus coalescent analyses. Using multilocus coalescent approaches, a species tree and divergence times can be estimated from a set of gene trees while accounting for gene-tree stochasticity. We utilized the conceptual strengths of a multilocus coalescent approach coupled with complete range-wide sampling to examine the speciation history of a broadly distributed, North American warm-desert toad, Anaxyrus punctatus. Phylogenetic analyses provided strong support for three major lineages within A. punctatus. Each lineage broadly corresponded to one of three desert regions. Early speciation in A. punctatus appeared linked to late Miocene-Pliocene development of the Baja California peninsula. This event was likely followed by a Pleistocene divergence associated with the separation of the Chihuahuan and Sonoran Deserts. Our multilocus coalescent-based reconstruction provides an informative contrast to previous single gene-tree estimates of the evolutionary history of A. punctatus.

Phylogenetic Placement of the Pygmy Alligator Lizard Based on Mitochondrial DNA

Abstract Morphological studies have proven inconsistent in establishing the phylogenetic placement and taxonomic assignment of Elgaria parva. Originally classified as Gerrhonotus parvus Knight and Scudday, this taxon was reassigned to Elgaria based on morphology. To investigate its phylogenetic affinities, we generated mitochondrial DNA sequence data and conducted phylogenetic analyses together with published sequences for a broad taxonomic sampling of anguid lizards. We conducted parsimony, likelihood, and Bayesian analyses of the data. Our results indicate that E. parva forms a clade with other Gerrhonotus rather than Elgaria. Furthermore, Elgaria and Gerrhonotus are not sister taxa. Based on our new molecular evidence, we suggest that E. parva be classified as Gerrhonotus parvus as originally described.

Pollution biomarkers in the spiny lizard (Sceloporus spp.) from two suburban populations of Monterrey, Mexico

Environmental pollution may severely impact reptile species in urbanized areas. The magnitude of the impact is analyzed in the present study using lizard tail tips for the quantitative evaluation of enzymatic biomarkers of pollution. Spiny lizards (Sceloporus serrifer and S. torquatus) were collected from two suburban localities in the Monterrey metropolitan area, Mexico: Chipinque Ecological Park, a natural protected area, and El Carmen Industrial Park (IP), a highly polluted site. Different enzymes were used as biomarkers including: acetylcholinesterase (AChE), butyrylcholinesterase (BChE), carboxylesterase (CaE), alkaline phosphatase (ALP), acid phosphatase (ACP), superoxide dismutase (SOD) and glutathione S-transferase (GST). The levels of AChE, BChE and ACP activity were not significantly different between localities. AChE and BChE, commonly used as biomarkers of neurotoxic polluting agents (e.g. organophosphate pesticides) do not appear to be affecting the populations from the study locations. In contrast, the levels of CaE, GST, ALP and SOD were significantly different between the localities. These biomarkers are regularly associated with oxidative stress and processes of detoxification, and generally indicate pollution caused by heavy metals or hydrocarbons, which are common in industrial sites. The data resulting from the analysis of these biomarkers indicate that these polluting agents are affecting the populations of Sceloporus in IP. The present work validates the possibility of conducting additional ecotoxicological studies using biomarkers in combination with a nondestructive sampling technique in species of spiny lizards that are abundant in many North America areas.

Comparison of venom composition and biological activities of the subspecies Crotalus lepidus lepidus, Crotalus lepidus klauberi and Crotalus lepidus morulus from Mexico

The rock rattlesnakes Crotalus lepidus comprise a group (lepidus, klauberi, morulus and maculosus) of poorly known mountain cold-tolerant snakes in Mexico. In particular, Crotalus lepidus morulus is a snake endemic of the northeast of Mexico, whereas Crotalus lepidus klauberi and C. l. lepidus are distributed in some regions of the north and central Mexico and southern U. S. Until now very little data are available from C. lepidus subspecies from Mexico, as the terrain inhabited by these snakes is generally steep and rugged. In this work, we have determined some biochemical and biological properties of C. l. morulus, C. l. klauberi and C. l. lepidus crude venoms. Some minor differences in venoms were noted in SDS-PAGE, HPLC profile and MALDI-TOF mass spectrometry analysis. Partial sequences of metalloproteinases, phospholipases A₂ (PLA₂) and galactose-specific lectins were identified in the venoms. Venoms of C. l. klauberi and C. l. lepidus had significantly higher hemorrhagic and lethal activities than C. l. morulus venom. Proteolytic activity in azocasein was higher in C. l. morulus venom, whereas gelatin hydrolysis was higher in C. l. klauberi. Fibrinogenolytic and PLA₂ activities were very similar in all venoms tested. The histological observations in the gastrocnemius muscle damaged by venoms from all the subspecies confirmed myonecrotic and hemorrhagic activities (at 3 and 24 h), which resulted in a poor regenerative response after 14 days. However, C. l. lepidus and C. l. klauberi venom induced a higher increase in the plasma activity of creatine kinase (CK), evidencing higher myotoxicity, whereas paw edema-inducing activity was higher in C. l. lepidus venom. The results indicate that the venoms from the three subspecies have similar protein profiles in electrophoresis, HPLC and molecular weight determinations. However, differences were found in the biological activities in mice. Notably, the venoms of C. l. lepidus and C. l. klauberi present higher toxicity (lower LD₅₀) and hemorrhagic activity than C. l. morulus venom.

New Species of Lampropeltis (Serpentes: Colubridae) from the Sierra Madre Occidental, Mexico

Abstract We describe a new species of Lampropeltis from the Pacific versant of the Sierra Madre Occidental in western México based on external morphology, scutellation, and molecular data. This species appears to be closely related to Lampropeltis pyromelana and Lampropeltis mexicana. Divergence may have resulted from geographic isolation on the west side of the Continental Divide in the Sierra Madre Occidental and subsequent adaptation to a unique ecological region.

Gerrhonotus parvus Knight & Scudday, 1985 (Squamata: Anguidae): new range extension and clutch size in the state of Nuevo León, Mexico

We report a female specimen of Gerrhonotus parvus that represents a new record for the municipality of Santa Catarina, Nuevo Leon, Mexico. This species was known previously from only three localities in the state: the municipalitiy of Galeana; the type locality, Los Rayones, where only one specimen was registered; and San Isidro Canyon in Santiago, which previously was the northernmost locality and where the largest number of specimens have been observed and collected. This new record extends the range of the species 48.2 km northeast of the nearest known locality in Santiago. In addition, the specimen laid six eggs, which is the largest clucth documented so far. The type locality is located in a transition zone between pine forest ( Pinus arizonica ) and open gypsophilous scrub. However, the nature of the microhabitats at the other localities, including the northernmost one reported here, suggests that the species has a preference for dry limestone canyons.

Sexual Dimorphism in the Alligator Lizard Gerrhonotus infernalis (Sauria: Anguidae): Implications for Sexual Selection

Sexual dimorphism is common in many clades of reptiles. The Texas alligator lizard (Gerrhonotus infernalis) is a lizard distributed in North America, from Texas in the southern United States to the state of San Luis Potosı́ in central Mexico. Very little data exist on the presence of sexual dimorphism and on the ecology of this species, particularly in Mexico. We document sexual dimorphism in a population of Gerrhonotus infernalis at Parque Ecológico Chipinque, Monterrey, Nuevo León, Mexico. We evaluated 12 morphological and one meristic character on 102 specimens. There were significant differences in the dimensions of the head and body, showing that there is sexual dimorphism in G. infernalis. Males showed positive allometry in cranial dimensions, while females showed isometric growth. Males had more bite marks, suggesting agonistic behavior in this species. This population of G. infernalis presents sexual dimorphism in body size and dimensions of the head, and this is likely a consequence of intrasexual selection. RESUMEN—El dimorfismo sexual es común en varios clados de reptiles. El falso escorpión (Gerrhonotus infernalis) es una lagartija que se distribuye en el norte de América, desde Texas en el sur de Estados Unidos de América, hasta el estado de San Luis Potosı́ en el centro de México. Existe poca información sobre el dimorfismo sexual y la ecologı́a de esta especie, particularmente en México. Documentamos el dimorfismo sexual en una población de Gerrhonotus infernalis en el Parque Ecológico Chipinque, Monterrey, Nuevo León, Mexico. Evaluamos 12 caracterı́sticas morfológicas y una merı́stica en 102 especı́menes. Hubo diferencias significativas en las dimensiones de la cabeza y del cuerpo, evidenciando la existencia de dimorfismo sexual en G. infernalis. El patrón de crecimiento fue alométricamente positivo en los machos e isométrico en las hembras. En los machos se registró un número mayor de marcas de mordidas, sugiriendo que existe conducta agonista en esta especie. Existe dimorfismo sexual en el tamaño del cuerpo y las dimensiones de la cabeza de G. infernalis en la población estudiada y probablemente dicho dimorfismo es consecuencia de la selección intrasexual. Sexual dimorphism is common in vertebrates and is frequently found in lizards (Butler and Losos, 2002; Molina-Borja, 2003; Butler et al., 2007; Kaliontzopoulou et al., 2007). Sexual dimorphism is expressed in morphological characteristics such as snout–vent length (Johnston and Bouskila, 2007; McBrayer and Anderson, 2007), length of limbs (Baird et al., 2003; Molina-Borja, 2003; Johnston and Bouskila, 2007; Ljubisavljevic et al., 2008), weight (Molina-Borja, 2003; Johnston and Bouskila, 2007), color (Baird et al., 2003; Johnston and Bouskila, 2007), and dimensions of the head (Herrel et al., 1996; Johnson et al., 2005; Husak et al., 2006; McBrayer and Anderson, 2007). Sexual dimorphism also is seen in ecological characteristics such as foraging (Parmelee and Guyer, 1995; Perry, 1996); social behavior (Molina-Borja, 2002; Baird et al., 2003) and selection of microhabitat (Butler et al., 2007; Williams and McBrayer, 2007). The principal causes of sexual dimorphism in lizards are often hypothesized to be related to sexual selection, niche segregation, and nonadaptive processes related to behavioral or physiological differences between the sexes (Butler and Losos, 2002; Cox et al., 2003; Molina-Borja and Rodrı́guez-Domı́nguez, 2004). Sexual selection may generate dimorphisms as a consequence of intrasexual and intersexual competition whereby a reproductive advantage is gained by one sex. For example, males may increase fighting ability by attaining greater body size or weaponry used in male–male combat. Presumably, winners of these combative encounters have increased access to mates, and these males would have a fitness advantage over smaller males, or males with smaller weapons (e.g., jaws; Lailvaux et al., 2004; Lappin and Husak, 2005). Sexual dimorphism also may evolve to decrease niche overlap. Many species are known to segregate important resources such as preferred prey or occupancy of microsites to optimize use of individual resources (Butler et al., 2007). Finally, sexual dimorphism may evolve as a byproduct of other behavioral or physiological processes such as patterns of differential growth or longevity (Stewart, 1985; Johnson et al., 2005; McBrayer and Anderson, 2007; Ljubisavljevic et al., 2008). Within genera or other lower taxonomic groups, sexual dimorphism can manifest itself in varying degrees in different characteristics (Molina-Borja, 2003; Butler et al., 2007). In anguid lizards (Barisia and Elgaria), sexual dimorphism is present in size of the head and body (i.e., snout–vent length; Vial and Stewart, 1989; Rutherford, 2004; McBrayer and Anderson, 2007). Stewart (1985) found annual variation in the degree of sexual dimorphism in Elgaria coerulea. Such variation could be due to year-to-year climatic and ecological conditions at particular study sites (e.g., temperature, rain, abundance of prey, etc.; Schäuble, 2004). Therefore, when assessing the presence and magnitude of sexual dimorphism, many extrinsic (e.g., temperature, precipitation, and humidity) and intrinsic (e.g., physiologic and genetic) factors must be considered. Gerrhonotus infernalis is commonly known as falso escorpión or Texas alligator lizard; it is distributed in North America from central to western Texas in the United States through Coahuila, entering into Nuevo Leon, Tamaulipas, and north of San Luis Potosı́ in México (Smith, 1979; Good, 1994). It is most often found in humid, shady, rocky areas. It is a relatively large lizard (180–200 mm snout–vent length; SVL), with short limbs and small claws. Males seem to have larger heads than do females of the same size. Adults can be found throughout the year but are less active during hot and cold months (summer and winter; Greene et al., 2009). Like other anguid lizards (Smith, 1979), G. infernalis is a secretive species in temperament and can be found moving slowly on leaf litter or hidden under rocks. Due to their secretive habits, insufficient information exists on the ecology, natural history, and potential for sexual dimorphism in this species, especially in the Mexican portion of its distribution. The objective of this study was to evaluate the sexual dimorphism of G. infernalis in morphological traits and to compare these data with those from other lizards to examine patterns of sexual dimorphism. MATERIALS AND METHODS—We conducted this study in Parque Ecológico Chipinque (25834–25835N, 100818–100823’W), in the municipalities of Monterrey and San Pedro Garza Garcı́a in the state of Nuevo León, Mexico. The park occupies 1,791 ha of a protected area, ‘‘Parque Nacional Cumbres,’’ within the Sierra Madre Oriental mountain range; elevation is between 600 and 2,200 m at Chipinque. The climate at Chipinque is semidry (300– 500 mm annual precipitation) with a noticeable rainy season in the summer. The average annual temperature ranges from18– 228C (Garcı́a, 1981). Five different types of vegetation are present at Chipinque: oak; oak-pine; pine-oak forest; mountain scrub;

Intra-specific Variation in the Protein Composition and Proteolytic Activity of Venom of Crotalus lepidus morulus from the Northeast of Mexico

The Tamaulipan rock rattlesnake (Crotalus lepidus morulus) is a small, cold-tolerant, mountain rattlesnake that occupies the Sierra Madre Oriental in southwestern Tamaulipas, central Nuevo Leon, and southeastern Coahuila in Mexico. The aim of the present study was to analyze and compare the protein profile and proteolytic activity of 16 individual and four pooled (representative of four regions Galeana, Santiago, Zaragoza, and Tamaulipas) venom samples of C. l. morulus from snakes collected in the northeast of Mexico. Individual and pooled venoms of C. l. morulus were analyzed by SDS-PAGE, gelatinolytic, and fibrinogenolytic assays. Additionally, the four pooled venoms were tested by 2-D electrophoresis and caseinolytic and hemorrhagic assays. Individually, venoms of C. l. morulus showed variation in their electrophoretic profile and proteolytic activity without an evident geographic trend. When comparing the pooled samples, venom from the south portion of the range (Zaragoza and Tamaulipas) showed higher proteolytic activity than samples from the central and north portion of the range (Galeana and Santiago, respectively). Furthermore, pooled venoms of C. l. morulus showed lower variation in electrophoretic profile than individual venoms. It is important to note that this is the first report of protein profile and enzymatic activities of venom of C. l. morulus.

AGGREGATION OF SCELOPORUS MINOR (SAURIA: PHRYNOSOMATIDAE) FROM CERRO EL POTOSI, NUEVO LEON, MEXICO

Abstract We report for the first time aggregation behavior in the lizard Sceloporus minor. The behavior was recorded at Galeana, Nuevo León, Mexico, where a group of ca. 30 individuals were observed under a rock associated with a stone wall. Weight, sex, snout-vent length, and total length were recorded for 22 individuals. Means of traits were: males—weight  =  18.9 g, snout-vent length  =  80.5 mm, total length  =  173.3 mm; females—weight  =  13.9 g, snout-vent length  =  72.9 mm, total length  =  161.1 mm. Sex ratio was 16 males∶6 females. Our observation extends the known elevational range of the species from ca. 3,000 m to 3,470 m.

Herpetofauna of the Cerro El Potosi Natural Protected Area of Nuevo Leon, Mexico: Status of the Ecological and Altitudinal Distribution

ABSTRACT: Cerro El Potosi is a Natural Protected Area under State jurisdiction and it is one of the highest peaks of the Sierra Madre Oriental. It is an interesting area as its flora and fauna are distributed along a 2000–3750 m altitudinal gradient. The purpose of this study was to conduct an inventory of the herpetofauna and to describe its distribution in relation to plant communities and altitude. In addition, we address the risk of extirpation of some of the species. Twenty-five field trips of three to four days each were made between October 2006 and October 2008. A total of 268 individuals of amphibians and reptiles were observed. The sampled plant communities and number of herpetofaunal species found were: farming areas, eight species; submontane scrubland, four; chaparral, five; Quercus spp, six; Pinus pseudostrobus, eight; Pinus ayacahuite-, five; Pseudotsuga menziesii, five; Pinus hartwegii, five; Pinus strobiformis, two; Pinus culminicola, five; and catastrophic fire deforestation areas, three. According to the literature, 41 species are known from the area, while only 16 taxa were found during this study. The non-parametric estimators for species diversity indicated that the number of species tend to rise as sampling increases; the curve has not reached totality. Its asymptote represents 84.21% of herpetofauna for the mountain.