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(a) Life-cycle diagram of the mesquite lizard (Sceloporus grammicus). Nodes represent size categories, arrows represent transition probabilities (in the case of growth or stasis) or contributions (in the case of fecundities) made by individuals in a particular category to other categories from 1 year to the next. F, fecundity; G, growth, which is defined as survival with progression to a larger size class; P, stasis, which is defined as survival staying in the same size class. Subscripts (ij) indicate the direction of the transition or contribution, from size class j to size class i. (b) Population projection matrix for S. grammicus. Terms in the matrix are equivalent to those in the life-cycle diagram. The matrix can be interpreted as a numerical representation of the life-cycle diagram.
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We conducted a 5 year demographic study in one population of the viviparous lizard Sceloporus grammicus Wiegmann, 1828 in central México. The population was structured in three size classes (juveniles, small adults, and asymptotic adults) for which we estimated annual survival and fecundity rates. A population projection matrix was constructed for...
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... rates of the different phases of the life cycle of S. grammicus represented by the three size classes into which we structured the population (i.e., ju- veniles, small adults, and asymptotic adults). The life-cycle diagram depicts all the transitions and contributions that can be observed among the size classes from 1 year to the fol- lowing year (Fig. 1a). When female lizards survive, they can either remain in the same size class (stasis, depicted with a P in both the life-cycle diagram and the transition matrix; Figs. 1a, 1b) or progress to a superior size class (growth, G in Figs. 1a, 1b). In most years (except transition 1994-1995), we observed certain proportion of juveniles ...
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... a P in both the life-cycle diagram and the transition matrix; Figs. 1a, 1b) or progress to a superior size class (growth, G in Figs. 1a, 1b). In most years (except transition 1994-1995), we observed certain proportion of juveniles surviving and growing more than one size class (to asymp- totic adults) from 1 year to the next (transition G 31 in Figs. 1a, 1b). Both adult categories contribute to juveniles by offspring production (fecundity, F in Figs. 1a, 1b). Ma- trix entries (a ij ), which translate the life-cycle diagram into a numerical and analytical tool, represent survival with sta- sis (in the main diagonal), survival with growth (in the sub- diagonals), and contribution to ...
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... size class (growth, G in Figs. 1a, 1b). In most years (except transition 1994-1995), we observed certain proportion of juveniles surviving and growing more than one size class (to asymp- totic adults) from 1 year to the next (transition G 31 in Figs. 1a, 1b). Both adult categories contribute to juveniles by offspring production (fecundity, F in Figs. 1a, 1b). Ma- trix entries (a ij ), which translate the life-cycle diagram into a numerical and analytical tool, represent survival with sta- sis (in the main diagonal), survival with growth (in the sub- diagonals), and contribution to juveniles by fecundity (in the first row) of a mean individual in size class j (columns) to size class i ...
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... (a ij ), which translate the life-cycle diagram into a numerical and analytical tool, represent survival with sta- sis (in the main diagonal), survival with growth (in the sub- diagonals), and contribution to juveniles by fecundity (in the first row) of a mean individual in size class j (columns) to size class i (rows) from 1 year to the next ( Fig. 1b; Caswell ...
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... addition, we also took into account the contribution that surviving females in the juvenile size class make to the same juvenile category (matrix entry a 11 ) from 1 year to the following year by means of offspring production. As de- picted in Fig. 1a, a proportion of juveniles survive and grow large enough to reach the small adult size class or even the asymptotic adult size class in one annual transition. Some of these ''growing'' juvenile females at the beginning of any particular annual transition exhibit a size that, although still within the threshold of the juvenile category ...
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... the corresponding estimated litter size. In consequence, we calculated the total contribution of juveniles to juveniles (the entry a 11 in all matrices) as a combination of the stasis of some juvenile females from 1 year to the next and the offspring produced by those large surviving and growing ju- veniles that begin reproduction (P 11 + F 11 in Figs. 1a, ...
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... growth rate simply by adding all the entries in the elasticity matrices that corresponded to each category or to each process ( Silvertown et al. 1993). Nevertheless, as the entry a 11 in the transition matrices is a combination of juve- nile stasis and fecundity (through the offspring produced by some of the growing juveniles; P 11 + F 11 in Figs. 1a, 1b), the corresponding elasticity (entry e 11 in the elasticity ma- trices) was partitioned into the proportion that is due to sta- sis and that is due to fecundity. Those proportions were added to the summed elasticity for stasis and fecundity, re- ...
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... A total of 84 individuals were collected from rocks or crevices, either by hand or using a slip-knotted rod. Only adult male individuals were used in this study, whose snout-vent length (SVL) was larger than the smallest size at maturity (> 45 mm), and that showed secondary sexual ventral coloration (Zúñiga-Vega et al., 2008;Bastiaans et al., 2014). Lizards were collected during the summer of 2021 at nine locations -three different altitudes in each of three different mountains-, from the Trans-Mexican volcanic belt. ...
High altitude environments provide a fertile ground for investigating the benefits of phenotypic adjustments at several levels of biological organization. Low oxygen partial pressure and low environmental temperature are the main limiting factors that promote phenotypic variation in different organs, such as the lung and heart. Although high-altitude environments act like natural laboratories, most morphological studies conducted to date lack replication. Here, we evaluated organ mass variation in nine populations of Sceloporus grammicus, throughout three altitudinal gradients (mountains) from the Trans-Mexican volcanic belt. A total of 84 individuals from three different altitudes at three different mountains were collected. Then, we used generalized linear models to analyze the pattern of variation in internal organs mass as a function of altitude and temperature. We observed a striking pattern of altitudinal variation in the size of cardiorespiratory organs: while heart mass increased with altitude and decreased with temperature, the lung showed a significant statistical interaction between mountain transect and temperature. Overall, our results support the hypothesis that cardiorespiratory organs should be bigger in populations occurring at higher altitudes. Moreover, the study of different mountain systems allowed us to observe some differences in one mountain in relation to the other two.
... We used 16S rRNA gene sequencing to compare bacterial community profiles of the stomach, small intestine, rectum, feces, and cloacal swabs (hereafter cloaca) of the mesquite lizard Sceloporus grammicus Wiegmann, 1828 (Fig. 1b) lizard is the most widely distributed species complex of lizards in Mexico, so its natural history is well known (Zúñiga-Vega et al. 2008;Díaz de la Vega-Pérez et al. 2019), and it is considered as a least-concern species according to the Red List of Threatened Species (Hammerson et al. 2007). As such, we considered this species as an excellent model organism to compare the accuracy of different nonlethal methods to characterize gut bac-terial communities of lizards. ...
Fecal samples or cloacal swabs are preferred over lethal dissections to study vertebrate gut microbiota for ethical reasons, but it remains unclear which nonlethal methods provide more accurate information about gut microbiota. We compared the bacterial communities of three gastrointestinal tract (GIT) segments, that is, stomach, small intestine (midgut), and rectum (hindgut) with the bacterial communities of the cloaca and feces in the mesquite lizard Sceloporus grammicus. The hindgut had the highest taxonomic and functional alpha diversity, followed by midgut and feces, whereas the stomach and cloaca showed the lowest diversities. The taxonomic assemblages of the GIT segments at the phylum level were strongly correlated with those retrieved from feces and cloacal swabs (rs > 0.84 in all cases). The turnover ratio of Amplicon Sequence Variants (ASVs) between midgut and hindgut and the feces was lower than the ratio between these segments and the cloaca. More than half of the core-ASVs in the midgut (24 of 32) and hindgut (58 of 97) were also found in feces, while less than 5 were found in the cloaca. At the ASVs level, however, the structure of the bacterial communities of the midgut and hindgut were similar to those detected in feces and cloaca. Our findings suggest that fecal samples and cloacal swabs of spiny lizards provide a good approximation of the taxonomic assemblages and beta diversity of midgut and hindgut microbiota, while feces better represent the bacterial communities of the intestinal segments at a single nucleotide variation level than cloacal swabs.
... Low thermal quality environments increase thermoregulation costs (Huey & Slatkin, 1976) in actively thermoregulating lizards (Blouin-Demers & Nadeau, 2005) such as S. grammicus (D ıaz de la Vega-P erez et al., 2019). Furthermore, various features of life-history traits are affected by elevation and low temperature, for example, we know that the growth rate and the number of offspring decrease at higher and colder sites (Lemos-Espinal et al., 1998;Z uñiga-Vega et al., 2008), while the time to reach sexual maturity and the duration of gestation increases at higher and colder sites (Guillette & Casas-Andreu, 1980;Ram ırez-Bautista et al., 2005;Z uñiga-Vega et al., 2008). In addition to being energetically expensive, aggressive behavior can be physiologically restricted by body temperature itself, which limits the muscular activity of lizards (Herrel et al., 2007). ...
... Low thermal quality environments increase thermoregulation costs (Huey & Slatkin, 1976) in actively thermoregulating lizards (Blouin-Demers & Nadeau, 2005) such as S. grammicus (D ıaz de la Vega-P erez et al., 2019). Furthermore, various features of life-history traits are affected by elevation and low temperature, for example, we know that the growth rate and the number of offspring decrease at higher and colder sites (Lemos-Espinal et al., 1998;Z uñiga-Vega et al., 2008), while the time to reach sexual maturity and the duration of gestation increases at higher and colder sites (Guillette & Casas-Andreu, 1980;Ram ırez-Bautista et al., 2005;Z uñiga-Vega et al., 2008). In addition to being energetically expensive, aggressive behavior can be physiologically restricted by body temperature itself, which limits the muscular activity of lizards (Herrel et al., 2007). ...
Aggressive behavior is performed in the context of intraspecific competition for gaining access to mates, food, or suitable territories. However, aggressive confrontations may divert time and energy from other important activities and increase the likelihood of suffering physical injury or predation. Aggressive behavior is particularly costly for ectotherms because it may reduce the time available for thermoregulation, which is a time‐consuming activity but indispensable for adequate maintenance of metabolic processes. In this study, we analyzed the long‐term effect of the thermal quality (i.e. the degree of discrepancy between the temperatures available in a given environment and temperatures that animals prefer) on the aggressive behavior of the mesquite lizard Sceloporus grammicus. Our hypothesis was that time allocated to aggressive behavior in low thermal quality environments is diverted from time spent on the acquisition and maintenance of an adequate body temperature. Accordingly, we found that lizards from the low thermal quality location (i.e. low environmental temperature) exhibited less aggressive behavior than those captured in middle and high thermal quality locations. Our results show that in the low thermal quality location aggressive behavior was almost absent, suggesting that this behavior may interfere with the acquisition and maintenance of an adequate body temperature. Therefore, it is likely that the benefits of thermoregulation outweigh those of aggressive behavior at low thermal quality locations.
... survival probability is considerably lower in early life stages compared to the adult life stage (Zúñiga-Vega et al. 2008, Massot et al. 2011, Kacoliris et al. 2013, and generally for reptiles, reported juvenile survival is approximately 13% lower than for conspecific adults, with average annual survival of juvenile lizards being 0.32 (Pike et al. 2008). Higher survival rates for adult Texas horned lizards, versus our documented rates for hatchlings, have been documented at various locations throughout the species' distribution: an adult survival rate of 0.59-0.70 at TAFB ), 0.01-0.47 for translocated lizards in north-central Texas (Miller et al. 2020), 0.09-0.54 ...
Habitat fragmentation has negative consequences on threatened and endangered species by creating isolated populations. The Texas horned lizard (Phrynosoma cornutum) is experiencing population declines and localized extirpations throughout its range and has been classified as a species of greatest conservation need in Oklahoma, USA. Younger age classes have been poorly studied but may be vital to the stability of remaining populations. To address gaps in knowledge concerning subadult (hatchling and juvenile) morphometrics, survivorship, and home range sizes, we studied 2 cohorts of subadults, for 2 years each, covering their hatching and juvenile years (2016–2019). We used a combination of radio‐telemetry and novel harmonic radar methodology to study a closed population of Texas horned lizards in 15 ha of native grassland at Tinker Air Force Base, Oklahoma. Population abundance for adults and juveniles was estimated as 56.5 ± 5.5 lizards and density as 7.96 lizards/ha. Our lowest estimates of survival indicated an average survival probability for the hatchling life stage of 0.285 (95% CI = 0.15–0.44), which is lower than for adults on the site. Average home range size increased from hatchling to adult life stages. Our results will have an immediate effect on the planning and assessment of ongoing headstart and management programs for Texas horned lizards. © 2021 The Authors. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society. We estimated Texas horned lizard hatchling survivorship using direct, field‐based monitoring methodology, and report ontogenetic increases in morphometrics and home range area from hatchling to adult life stages. Our results can be used in the planning and assessment of future headstart and management programs for this threatened lizard.
... This suggests that relative density may be a measure of population variation that predicts the survival value for both sites. However, in some cases lower survival probability has been observed in populations with high density than in populations with low density (Stearns 1992;Zúñiga-Vega et al. 2008). Survival rates and probabilities of recapture obtained here for males and females were higher compared to those reported for Anolis nebulosus (Hernández-Salinas 2014), Xenosaurus grandis (Zúñiga-Vega et al. 2007), and Sceloporus grammicus (Pérez-Mendoza et al. 2014). ...
... La mayor parte de los estudios efectuados en la estación han sido orientados a la ecología de poblaciones y reproducción tanto de anfibios como de lacertilios (p.e. Eliosa- León, 1990;Cuéllar et al., 1996;Andrews et al., 1997;Andrews et al., 1999;Hernández-Gallegos et al., 2002;Rodríguez-Romero et al., 2002;Zúñiga-Vega et al., 2008;Bastiaans, 2013). Sin embargo, hay pocos estudios enfocados a ecología de comunidades (ver Maass et al., 1981;Pérez-Roblero, 2014), los cuales no representan cuantitativamente la diversidad de anfibios y reptiles de la EFEZ y de sus hábitats. ...
Se analizaron los patrones de diversidad de anfibios y reptiles en tres hábitats distintos de un ambiente templado: Pino, Pino-Aile y Pino-Oyamel de la Estación Forestal Experimental Zoquiapan (EFEZ), en el área natural protegida Parque Nacional Iztaccíhuatl-Popocatépetl-Zoquiapan. Se realizaron muestreos sistemáticos de la herpetofauna en transectos en banda de 1,000 m de largo por 10 m de ancho, de 2015 (mayo-julio y septiembre-noviembre) a 2016 (enero-marzo). Se registró un total de 4,762 individuos correspondientes a siete familias, diez géneros y 15 especies (cinco anfibios y diez reptiles). Las familias con más especies y abundancia fueron Phrynosomatidae y Pletodontidae. La riqueza de especies fue mayor (15 especies) en el hábitat Pino-Aile, mientras que la abundancia fue significativamente más alta ( = 70.18 ind./ha) en el hábitat Pino. El hábitat Pino-Oyamel presentó la menor riqueza (13 especies) y abundancia ( = 36.66 ind./ha). La mayor diversidad (1D = 5.16) se registró en Pino-Aile, seguido por Pino-Oyamel (1D = 4.01) y Pino (1D = 3.84). La distribución de abundancias de las especies se ajustó a la serie logarítmica de Fisher. Las especies más comunes en los tres hábitats fueron Sceloporus grammicus y Pseudoeurycea leprosa, mientras que todas las serpientes se consideraron especies raras. El 86.7% de las especies son endémicas a México, de las cuales 69.2% son endémicas a la Faja Volcánica Transmexicana. El 33.3% de las especies están amenazadas y el 26.7% sujetas a protección especial en la NOM-059-2010. Cuatro de ellas están categorizadas por la IUCN, de las cuales 6.7% está en peligro, 13.3% es vulnerable y 6.7% está casi amenazada. En términos de la relación especies-área, la riqueza de especies de anfibios y reptiles, y la presencia de endemismos en la EFEZ son altas. Este estudio contribuye a un conocimiento sobre la riqueza, abundancia, distribución y diversidad de anfibios y reptiles de los hábitats templados de la estación, que sentará precedentes para el desarrollo de estrategias futuras de conservación de la biodiversidad y en particular de la herpetofauna.
... La mayor parte de los estudios efectuados en la estación han sido orientados a la ecología de poblaciones y reproducción tanto de anfibios como de lacertilios (p.e. Eliosa- León, 1990;Cuéllar et al., 1996;Andrews et al., 1997;Andrews et al., 1999;Hernández-Gallegos et al., 2002;Rodríguez-Romero et al., 2002;Zúñiga-Vega et al., 2008;Bastiaans, 2013). Sin embargo, hay pocos estudios enfocados a ecología de comunidades (ver Maass et al., 1981;Pérez-Roblero, 2014), los cuales no representan cuantitativamente la diversidad de anfibios y reptiles de la EFEZ y de sus hábitats. ...
We analyzed the diversity patterns of amphibians and reptiles in three different habitats of a temperate environment: Pine, Pine-Alder and Pine-Fir of the Estación Forestal Experimental Zoquiapan (EFEZ), in the protected natural area Parque Nacional Iztaccíhuatl-Popocatépetl-Zoquiapan. Systematic samplings of the herpetofauna were carried out in belt transects of 1,000 m long and 10 m wide, from 2015 (May-July and September-November) to 2016 (January-March). A total of 4,762 individuals were recorded corresponding to seven families, ten genera and 15 species (five amphibians and ten reptiles). The families with more species and abundance were Phrynosomatidae and Pletodontidae. Species richness was greater (15 species) in the Pine-Alder habitat, whereas abundance was significantly higher ( x ¯= 70.18 ind./ha) in the Pine habitat. The Pine-Fir habitat exhibited the lowest richness (13 species) and abundance ( x ¯= 36.66 ind./ha). The highest diversity ( 1 D = 5.16) was recorded in Pine-Alder, followed by Pine-Fir ( 1 D = 4.01) and Pine ( 1 D = 3.84). Species’ abundance distribution fitted the Fisher logarithmic series. The most common species in all three habitats were Sceloporus grammicus and Pseudoeurycea leprosa, while all snakes were considered rare species. The 86.7% of the species are endemic to Mexico, of which the 69.2% are endemic to the Trans-Mexican Volcanic Belt. The 33.3% of the species are threatened and 26.7% are under special protection in the NOM-059-2010. Four of these are categorized by the IUCN, of which the 6.7% is endangered, 13.3% is vulnerable and 6.7% is near threatened. In terms of the species-area relationship, amphibians and reptiles’ species richness, as well as the occurrence of endemism in the EFEZ are high. This study contributes to the knowledge on the richness, abundance, distribution and diversity of amphibians and reptiles of the temperate habitats of the station, which would lay the basis to the development of strategies for the conservation of herpetofauna biodiversity.
... This can result in the production of offspring of greater size and therefore greater RCM, as may be happening in the females of Jojutla and Paso del Chivo. Thus, females from these two populations may give birth to larger offspring as compared to females from Chamela, because females of the former populations are perhaps better fed during the sampling period, or are subject to less intense predation pressure (Dunham 1982, Zúñiga-Vega et al. 2008, Bock et al. 2010. ...
Local and geographic variation in several life history characteristics (body size at sexual maturity, clutch size, clutch frequency, egg volume, offspring size) were analysed in the arboreal lizard Urosaurus bicarinatus in three populations (Chamela, Jalisco; Jojutla, Morelos; and Paso del Chivo, Michoacan) from two different environments (tropical dry forest and thorn bush) in Mexico. Variations in these life history traits were found to exist between populations. Adult females from Chamela exhibited smaller snout–vent length (SVL) than females from Jojutla and Paso del Chivo. A similar pattern was found in others reproductive characteristics, including clutch size, relative clutch mass, egg volume, and hatchling SVL. These differences could be interpreted in terms of trade-offs, where some populations or species under conditions of low resource availability and high mortality tend to expend higher costs on reproduction; such could be the case in the population of Chamela. However, more studies are needed in many species with a broad geographic distribution to better understand the effects of the environment and genetics on variation in life histories.
... Variables of perch height were log 10 -transformed to increase the possibility of a normal distribution. Normality of the data was performed by W Shapiro-Wilk test, recommended for sample sizes >150 (Shapiro et al. 1968;Zar 1999). The relationship among microhabitat use and perch height from the eight populations was evaluated with a canonical correspondence analysis (CCA; Ter Braak 1986). ...
Studies on habitat use have often helped explain observed variation in morphology, behavior and reproductive characteristics among populations within a single species. Here we analyze morphological and ecological characteristics of individuals from the Sceloporus grammicus species complex from 7 different localities (CER, El Cerezo; PAC, Pachuca; HUI, Huichapan; EZA, Emiliano Zapata; SMR, San Miguel Regla; LMJ, La Mojonera; and LMZ, La Manzana) in the state of Hidalgo, and one locality (Cahuacán) in the State of Mexico. A canonical correspondence analysis (CCA) showed that females from PAC, EZA, LMZ, HUI, SMR and CAH populations use similar microhabitats characterized mostly by bare soil, in females from LMJ and CER use microhabitats characterized primarily by vegetation and rocks. Females were observed using 12 different types of perches. With regard to perch height use, the CCA showed that females from PAC, LMJ, LMZ, SMR, CER and CAH populations were correlated with height to nearest perch (HNP), in the rest of the females were not related to any perch use variable. In contrast, the CCA showed that males from PAC, LMJ and CAH were characterized by microhabitats with higher vegetal coverage, while males from LMZ and CER used microhabitats composed of bare soil, but males from HUI and SMR populations used microhabitats composed chiefly of bare soil and rocks. With respect to perch height use, the CCA showed that males from PAC, LMJ, EZA and LMZ were correlated with distance to the nearest perch, but the rest of the males were not correlated with any perch use variables. Males were observed in 9 different perch types. The males were larger than the females in all morphological variables analyzed. Moreover, in both sexes the snout–vent length is positively correlated with all morphological variables, and although both the slope and ordinate of the origin of all morphological variables were larger in males than females, the analysis of covariance indicated that there is no increase in the morphological variables with increasing SVL between sexes. Our results suggest that variation in habitat use and morphology among populations is an adaptive response (phenotypic plasticity) to the environmental conditions where these populations of Sceloporus grammicus occur. © 2016 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd
... Prenuptial reproductive pattern terms, such as gonadal recrudescence, sex steroid production, and gametogenesis occur in advance of mating, whereas postnuptial reproductive patterns occur following mating. In other words, in a highelevation population of Sceloporus grammicus in Parque Nacional de Zoquiapan in central Mexico, an active reproductive event occurring in the early fall is described as dissociated from testicular recrudescence in males but is associated with the initiation of ovarian recrudescence in females Casas-Andreu, 1980, 1981;Zuniga-Vega et al., 2008). This is in contrast to S. grammicus from Teotihuacan, Mexico, in which testicular recrudescence and breeding occur in the summer and fall, at the onset of female ovarian recrudescence (Jimenez-Cruz et al., 2005). ...
We monitored testicular and ovarian morphologies,seminiferous tubules,the sexual segments of the kidneys (SSK),follicular histologies,and male testosterone and female estradiol to define the reproductive pattern of Calotes emma and Calotes versicolor. Samples were collected monthly at Sakaerat Environmental Research Station in Thailand for 1 year. Testicular hypertrophies occurred at a time characteristic for each species,with their time course corresponding well to both active spermatogenesis and the hypertrophied SSK. Gravid females were also found at a time characteristic for each species. In active reproductive females,oviductal eggs were concomitantly encountered with ovarian vitellogenic follicles. The previtellogenic and vitellogenic follicles corresponded well to granulosa layer alterations. The distinct large pyriform cells were present in the granulosa layer of previtellogenic follicles but disappeared from the vitellogenic follicles. Male testosterone levels rose during testicular and SSK hypertrophies,and female estradiol levels increased during active reproductive stages of late vitellogenic follicles and gestation. We suggest that the reproductive patterns of C. emma and C. versicolor fall into the same reproductive pattern of annual continual reproduction,but that the time courses of such events are different in the 2 Calotes,and even in individuals of the same Calotes population.
