Abstract
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.
Highlights
Knowledge of the reproductive potential of a population is fundamental to understanding its life history (Stearns 1989) and ecological status
The study site is located at Ixtapan de la Sal, southeastern Estado de México, north of the Río Balsas Basin, in Central Mexico (18°50'30"N, 99°39'0"W), at an altitude of 2090 m a.s.l. (Fig. 2), which is considered an unusually high elevation for teiid lizards (Vitt and Breitenbach 1993)
The clutch size of A. costatus costatus is larger than the mean clutch size in the genus Aspidoscelis
Summary
Knowledge of the reproductive potential of a population is fundamental to understanding its life history (Stearns 1989) and ecological status. Aspidoscelis lizards are considered to be wide foragers in search of their prey (Paulissen 1987; Utsumi et al 2020) Due to their active foraging strategy, body shape, and escape strategies, species in the genus Aspidoscelis. Gisela Granados-González et al.: High elevation clutch production in a whiptail lizard tend to show a relatively small clutch size, proportional to their body mass (Vitt and Breitenbach 1993). Based on Tucker et al (2016) the name A. costatus costatus replaces A. costata costata (sensu Reeder et al 2002) This species inhabits various ecological habitats and elevations in the states of Mexico, Guerrero, Morelos, Puebla, Tlaxcala, and Oaxaca (Maslin and Secoy 1986; Gómez-Benitez et al 2016; Méndez de la Cruz et al 2018; Barley et al 2019). Our study reports the clutch size and number of clutches in a different unique high-elevation population (> 2000 m) of Balsas Basin Whiptail (Fig. 1), which is among the largest clutch sizes in a population of the genus Aspidoscelis
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