No abstract

La distribución del complejo Aspidoscelis gularis en México ha sido difícil de modelar debido a los problemas taxonómicos que enfrentan sus integrantes y a que los modelos publicados excluyen zonas típicas donde los taxones han sido reportados. El objetivo de este trabajo fue actualizar la información sobre la distribución del complejo A. gularis y proponer un modelo aplicable a grupos de especies considerados “complejos”, así como para cualquier nivel taxonómico. La información generada permitió desarrollar un modelo de distribución con el algoritmo Tipicidad de Mahalanobis en IDRISI Taiga y se validó con el área bajo la curva (AUC), la cual obtuvo un valor de 0.932. La distribución modelada abarcó estados pertenecientes al Altiplano Mexicano. Se encontró que los taxones del complejo están asociados con la vegetación característica del Altiplano Mexicano clasificada como desierto Chihuahuense compuesta principalmente por matorrales xerófilos y pastizales, lo que sugiere un factor que limita su distribución en el norte hasta el centro de México, similar con otros grupos de reptiles.

Clutch size and number of clutches per reproductive cycle are important life history traits that can be influenced by anatomical, physiological, evolutionary, and ecological factors. This report on the clutch size and number of clutches of an endemic Mexican whiptail lizard, Aspidoscelis costatus costatus (Cope, 1878), is based on a study of population at an unusually high elevation for a member of this genus. The study site is located in Ixtapan de la Sal, southeastern Estado de México, Central Mexico, at 2090 m a.s.l. Lizards were sampled in June 2006, and from May to July 2007, where females of Aspidoscelis costatus costatus were collected by hand along a drift fence. Female reproductive condition was evaluated based on abdominal palpation for presence of developing eggs; clutch size was determined by actual counts of either vitellogenic follicles or oviductal eggs. The smallest reproductive female was 77 mm snout-vent length; females produced a minimum of two clutches during the breeding season, the mean clutch size of 6.5 eggs (n = 33) was one of the largest reported for the genus. However, both length and width of its eggs, and the relative clutch mass have not been diminished by development of a large clutch. Additionally, comparisons of clutch size were undertaken within the polytypic A. costatus complex, within the genus Aspidoscelis, and between certain genera of whiptail lizards. This apparently represents the first study of whiptail lizards (genus Aspidoscelis), assessing the aforementioned reproductive characteristics, in a population above 2000 m.

<p>El género <em>Aspidoscelis </em>es un grupo de lagartijas distribuido ampliamente en México, los miembros del género son semejantes en características, morfológicas, ecológicas, fisiológicas y conductuales a lo largo de su distribución; presentan modo de paridad ovípara, son forrajeros activos con preferencia por los hábitats abiertos y con temperaturas corporales elevadas. Debido a estas similitudes y a los eventos de hibridación frecuentes al interior del grupo, <em>Aspidoscelis </em>es considerado un género complicado, con relaciones filogenéticas aún por resolver.<strong></strong></p>

Rainfall implications on body size evolution of Aspidoscelis gularis (Squamata: Teiidae). Life history traits are highly variable attributes that maximize organisms's fitness. The relationship of weight and body size with environmental changes and habitat heterogeneity has been documented in previous reports; and size and body shapes are both considered life history attributes that are associated with rainfall, that boost available resources in the environment. While in Aspidoscelis genus, clutch size and relative mass are mainly associated with latitude and altitude, in Aspidoscelis gularis, winter rainfall favors two reproductive seasons, which may determine season variable clutch size. With the aim to study this, samplings were undertaken from May-July 2013, and May-September 2015. A total of 65 individuals lizards of the Southeast clade were obtained, and body length and interaxilar distance measurements were taken; furthermore, hepatic tissue samples were taken for DNA extraction, which allowed us to analyze phylogenetic relationships through a Bayesian Inference analysis, and subsequently, to apply Phylogenetic Comparative Methods (like phylogenetic signal, phylogenetically independent contrasts and reconstruction of ancestral character). Our results showed that there is a low phylogenetic signal regarding body size and shape, while the phylogenetically independent contrasts and reconstruction of ancestral characters suggest that small body sizes are associated to locations with highest rainfall. This can be associated to an establishment of an early sexual maturity, which reflects the maximum size of adults. Furthermore, according to an ANOVA and ANCOVA, there were statistically significant differences in body size and shape respectively, which promote a system for sexual competition for males and a system for fertility in females. These results were important to determine the effect of rainfall on some life history traits, pointing out that lizards of the Southeast clade, belonging to the A. gularis complex were able to face different selection pressures, determined by the environment. Rev. Biol. Trop. 65 (2): 725-733. Epub 2017 June 01.