Natural history of Valentin's rock lizard (Darevskia valentini) in Armenia

Abstract

Valentin's rock lizard (Darevskia valentini) is suggested to be the parent for several parthenogenetic species (e.g., D. armeniaca, D. bendimahiensis, D. sapphirina, and D. unisexualis) that evolved through hybridization. Complex evolutionary processes (including reticulate evolution) are occurring within the areas where Valentin's rock lizard coexists with these and other rock lizards. Hence, a detailed biological specification of this species is important for understanding how vertebrates evolve. Valentin's rock lizard is a long-lived (up to 9 years), small diurnal lizard with larger females than males, which is unlike other species of the genus. Their relatively large eggs and early reproduction period, which occurs just after emergence from winter shelters, are adaptations for living in a high elevation climate (higher than 2 000 m a.s.l.). Their body temperatures (31-32 °С) are comparable to body temperatures of rock lizards living in milder climates, though female body temperature is more dependent on substrate temperature and basking due to their lower activity than that found in males. Population density fluctuates from several individuals to several hundred per hectare and is not affected by parthenogen coexistence, although hybrids do occur in sexually biased populations where males are more common than females. The male home range is larger than that of females, though these home ranges broadly overlap. Prey is not limited in the mountain meadows and Valentin's rock lizards feed on a great variety of arthropods. Infanticide occurs in high-density populations.

Keywords: Darevskia valentini; Home range; Population density; Reproduction; Seasonal activity; Skeletochronology.

Figure 1. Morphology and external view of studied lizards

A: Male Darevskia valentini; B: Female D. valentini; C: D. unisexualis; D: D. armeniaca; E: Head of D. armeniaca with one row of scales between tympanic shield and mid temporal scale; F: Head of D. valentini female; G: Female triploid hybrid between D. valentini and D. unisexualis.

Figure 2. Distribution map of Valentin’s lizard (D. valentini) in Armenia and adjacent areas (Arakelyan et al., 2011 with changes)

Survey areas are marked by stars, 1: Mets Sepasar (D. valentini; D. raddei nairensis; D. armeniaca), 2: Kuchak (D. valentini; D. armeniaca; D. unisexualis), 3: Lchashen (D. valentini; D. armeniaca; D. unisexualis), 4: Sotk populations (D. valentini; D. armeniaca).

Figure 3. Climatographs (data from https://ru.climate-data.org) for cities closest to the main survey areas

A: Ashotsk (Shirak Province, area of Mets Sepasar); B: Aparan (Aragatsotn Province, area of Kuchak).

Figure 4. Typical landscapes inhabited by D. valentini

High-elevation meadows with stony outcrops in Mets Sepasar (A) and Kuchak (B). Steep cliffs in the Akhuryan River valley in the Mets Sepasar area (C).

Figure 5. Body lengths and ages of lizards from four populations (Mets Sepasar, Sotk, Lchashen, and Kuchak)

n=112 ind. There was a positive correlation between age and SVL for males and females (Rs=0.740, P<0.0001 in males and Rs=0.825, P<0.0001 in females).

Figure 6. Number of observed adult lizards on the transect in Mets Sepasar on the high-elevation meadow in 2016

Figure 7. Daily activity of D. valentini in Mets Sepasar on the high-elevation meadow (A) and Akhuryan River valley (B) on 14 June 2016

Juveniles and subadults of these two species look similar from a distance and were therefore combined.

Figure 8. Joint basking (A) of male N149 and female N140 in 2016; mating (B) of male N8 and female N13 in 2014

Figure 10. Feeding observations of the Valentin’s rock lizards

А: Adult female eating a juvenile; B: Subadult eating“forget-me-not”; C: Female catching a locust.

Figure 11. Lizard body, substrate and ambient temperatures

A: Measurements of body temperature of male and female D. valentini from Sepasar and Kuchak (n=25F+27M). There was a positive correlation between female body temperature and substrate temperature (Rs=0.644, P=0.002), but not between male body temperature and substrate temperature (Rs=–0.0256, P=0.90. B: No relationship was found between body temperature and ambient temperature (Males: Rs=0.0778, P=0.70; Females: Rs=0.1208, P=0.38).

Figure 12. Mean (±SE) body and preferred ambient temperature of female parthenogenetic D. armeniaca (n=10), female D. valentini (n=9), and male D. valentini (n=10) from Mets Sepasar

Each individual was measured 12 times throughout the day.

Figure 9. Distribution of feeding objects found in feces of Valentin’s lizards (n=205) and by observation (n=32)