Research Article |
Corresponding author: Gisela Granados-González ( ggranadosg@uaemex.mx ) Academic editor: Günter Gollmann
© 2020 Gisela Granados-González, Carlos Pérez-Almazán, Aldo Gómez-Benitez, James Martin Walker, Oswaldo Hernández-Gallegos.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Granados-González G, Pérez-Almazán C, Gómez-Benitez A, Walker JM, Hernández-Gallegos O (2020) Aspidoscelis costatus costatus (Squamata, Teiidae): high elevation clutch production for a population of whiptail lizards. Herpetozoa 33: 131-137. https://doi.org/10.3897/herpetozoa.33.e54901
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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.
Balsas Basin Whiptail, Central Mexico, clutch size, female size, Estado de México, relative clutch mass
Knowledge of the reproductive potential of a population is fundamental to understanding its life history (
Although Western Mexican Whiptail [Aspidoscelis costatus (Cope, 1878)] is currently treated as a polytypic species (
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.
Females of A. costatus costatus were captured by hand along a drift fence during their activity period (09:00–17:00 h) in June 2006, and from May to July 2007. The reproductive condition of each adult female was evaluated based on an abdominal palpation and a visual assessment, where the vitellogenic/gravid females showed an expanded contour in the abdomen region (
We evaluated the differences between slopes and intercepts of regression lines of vitellogenic follicles and number of oviductal eggs against SVL. The relationship of clutch size and SVL of females was evaluated by Pearson’s correlation coefficient. Moreover, we evaluated the differences (using a Student’s t test) of clutch size, size of eggs and RCM of A. costatus costatus with other species of Aspidoscelis using data from literature. All data were tested for normality via a Kolmogorov-Smirnov test. Analyses were performed in STATGRAPHICS Centurion XV.II, and results were deemed significant if p < 0.05.
The smallest reproductive female was 77 mm SVL, a larger size at first clutch production than recorded for several subspecies of A. costatus (
Mean egg length and mean egg width for selected parthenogenetic* and gonochoristic species in the genus Aspidoscelis.
Species | Egg length (mm) | Egg width (mm) | Source |
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Aspidoscelis costatus barrancarum | 14.0 | 9.0 |
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Aspidoscelis costatus costatus | 14.1 | 8.5 | This study |
Aspidoscelis costatus costatus | 14.7 | 8.8 |
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Aspidoscelis costatus huico | 14.4 | 8.2 |
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Aspidoscelis costatus nigrigularis | 14.5 | 8.0 |
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Aspidoscelis cozumela* | 15.3 | 8.5 |
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Aspidoscelis gularis | 13.5 | 7.2 |
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Aspidoscelis hyperythrus | 14.5 | 7.4 |
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Aspidoscelis inornatus | 13.5 | 6.7 |
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Aspidoscelis lineatissimus | 14.4 | 9.7 |
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Aspidoscelis neomexicanus* | 15.9 | 7.9 |
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Aspidoscelis parvisocius | 13.5 | 8.5 |
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Aspidoscelis sacki | 16.4 | 10.1 |
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Aspidoscelis sonorae* | 14.2 | 8.2 |
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Aspidoscelis tesselatus* | 17.1 | 9.3 |
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Aspidoscelis tigris | 17.9 | 10.0 |
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Aspidoscelis uniparens* | 13.1 | 7.1 |
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Aspidoscelis is the most speciose genus (43 species; Uetz and Hõsek 2020) within the family Teiidae. This genus is divided into five clades (
There have been numerous studies of reproductive characteristics in populations currently allocated to A. costatus. Larger clutch means and maximum clutch sizes characterize the two samples of A. costatus costatus from the southerly latitudes and higher elevations in Estado de Mexico (this study, Lopez-Moreno et al. 2016), compared to smaller clutch means and smaller maximum clutch sizes for samples of Aspidoscelis costatus barrancarum (Zweifel, 1959) (mean 3.92, range 2–7 eggs, SVL 70–107 mm), Aspidoscelis costatus huico (Zweifel, 1959) (4.4 ± 0.23, 2–8 eggs, SVL 65–105 mm), Aspidoscelis costatus nigrigularis (Zweifel, 1959) (4.4 ± 0.26, 1–7 eggs, SVL 62–105 mm), and Aspidoscelis costatus griseocephalus (Zweifel, 1959) (3.8 ± 0.37, 2–6 eggs, SVL 61–96 mm) from more northerly latitudes and lower elevations (
Both ecological and evolutionary factors may adjust the reproductive output in lizards (
The elongated body shape (typical of Aspidoscelis lizards) is one constraint on clutch size in the genus, but there may also be an added phylogenetic constraint in certain species (see
The anatomical appellation “whiptail lizards” not only refers to individuals of the genus Aspidoscelis, distributed in North and Central America, but also to lizards of the teiid genera Ameivula, Aurivela, Cnemidophorus, Contomastix, and Glaucomastix (
Described as having peculiar reproduction, the whiptail lizard of Bonaire Island, Netherland Antilles, South America, was referenced as C. murinus by
Although data collected suggest a high reproductive output in A. costatus costatus at Ixtapan de la Sal, there are multiple variables that should still be investigated such as dorsal coloration, interlimb distance, and coelomic volume. These future studies will provide a holistic view of reproduction to see if the females in our population have adopted atypical strategies (i. e., seasonal dorsal coloration and widening of the abdominal area), which help to maintain a high-reproductive output as in A. costatus costatus from Tonatico (