Fact-checked by Grok 2 weeks ago

Viviparous lizard

The viviparous lizard (Zootoca vivipara), commonly known as the common lizard, is a small Eurasian reptile in the family Lacertidae, distinguished by its unique bimodal reproductive strategy that includes both live birth (viviparity) and egg-laying (oviparity) across different populations, making it the only lizard species known to exhibit such variation.^[1]^[2] Measuring 50–77 mm in snout-vent length and weighing 2–5 g, adults display sexual dimorphism: males feature brighter coloration with yellows, greens, and blues on the flanks, white dorsal spots, and a thicker tail base, while females are duller brown or gray for camouflage.^[1] This species inhabits a wide range of environments, including peat bogs, heathlands, meadows, dunes, and woodland edges, often near water sources, and is highly adaptable to cold climates and elevations up to 2,800 m.^[1]^[2] With the broadest distribution of any non-marine reptile, Z. vivipara ranges across Europe (from Ireland to the Urals), northern Asia (including Siberia, China, and Japan), and extends farther north than any other reptile, reaching latitudes up to 68°N in Scandinavia and Russia.^[1]^[2] Reproduction occurs annually, with females reaching maturity at around two years; viviparous populations give birth to 3–15 fully developed young after a 3-month gestation, while oviparous ones (primarily in the southwest, such as the Pyrenees) lay 5–12 eggs that hatch externally.^[1]^[2] The species is diurnal and solitary, hibernating from October to March, and communicates via visual, olfactory, and auditory signals, with populations generally stable and classified as Least Concern by the IUCN, though protected in some regions like Switzerland due to habitat loss.^[1]^[3]

Taxonomy and nomenclature

Etymology

The scientific name Zootoca vivipara derives from Greek and Latin roots that emphasize the species' distinctive reproductive mode. The genus name Zootoca combines the Greek words zōon (meaning "animal" or "living being") and tokos (meaning "birth" or "offspring"), referring to the lizard's ability to retain eggs internally until hatching, a form of live-bearing.^[4] The specific epithet vivipara comes from Latin vivus (alive) and pario (to bring forth or produce), directly translating to "live-bearing," which highlights viviparity as a key trait distinguishing this lizard from most oviparous reptiles.^[5] The name was first proposed in 1787 by Nikolaus Joseph von Jacquin as Lacerta vivipara in his work on Viennese fauna, where he noted the species' viviparous reproduction without providing a formal description, rendering it a nomen nudum under modern nomenclatural rules.^[6] The valid description and binomial establishment came later in 1823 by Martin Hinrich Lichtenstein, who formalized Lacerta vivipara based on specimens from Siberia.^[7] In 2007, Edward N. Arnold, Oscar J. Arribas, and Salvador Carranza reclassified the species into the newly erected genus Zootoca following a comprehensive phylogenetic analysis of the Lacertini tribe, which used molecular data to delineate monophyletic groups and resolve the polyphyletic nature of the former Lacerta genus. Common names for Z. vivipara reflect its broad European and Asian distribution and reproductive uniqueness, including "common lizard" or "viviparous lizard" in English, "Waldeidechse" (forest lizard) in German, and "живородящая ящерица" (live-bearing lizard) in Russian.^[5]

Classification and subspecies

The viviparous lizard, Zootoca vivipara, is classified within the family Lacertidae, order Squamata, and is the only species in the monotypic genus Zootoca.^[2]^[8] Several subspecies of Z. vivipara are recognized based on morphological traits, such as scalation patterns and body proportions, as well as geographic isolation. The nominate subspecies Z. v. vivipara occurs widely across central and northern Europe, from the British Isles to Siberia. Z. v. pannonica is restricted to the western Balkan Peninsula and adjacent areas, including parts of Slovakia. Z. v. louislantzi, an oviparous form, inhabits the Pyrenees region of northern Spain, Andorra, and southwestern France.^[2]^[9] Phylogenetic analyses have identified six major genetic clades within Z. vivipara, which differ in reproductive modes—ranging from fully viviparous to oviparous—and adaptations to local climates, such as tolerance to temperature variability.^[10] Surget-Groba et al. (2006) showed that viviparity has evolved multiple times independently, as viviparous populations form a polyphyletic group with at least three transitions from oviparity. Complementing this, Cornetti et al. (2015) used mitochondrial and nuclear DNA, along with ecological niche modeling, to demonstrate reproductive isolation and potential species boundaries between viviparous (Z. v. vivipara) and oviparous (Z. v. louislantzi) lineages in Pyrenean contact zones, supporting further taxonomic revision.^[11]

Physical characteristics

Morphology

The viviparous lizard (Zootoca vivipara) is a small lacertid species characterized by an adult snout-vent length (SVL) of 40–80 mm, with total body length typically ranging from 150 to 200 mm due to the elongated tail often exceeding the SVL by up to 1.5 times. Adults typically weigh 2–5 g.^[1]^[12]^[13] The body form is slender and quadrupedal, adapted for terrestrial life, with the head and body not strongly depressed and covered dorsally by small, granular scales numbering 25–37 across the mid-back.^[7] Ventral scales are imbricate, and the collar is serrated, contributing to a textured integument suited for navigating ground litter and low vegetation.^[7] Limbs are well-developed and robust, enabling rapid bursts of movement for foraging and escape on the ground, as well as climbing through low shrubs and grasses. The tail is thick at the base and tapers distally, serving as a counterbalance during locomotion and capable of autotomy—a fracture plane allows voluntary detachment as a defense against predators, with regeneration possible afterward.^[14] Coloration variations are linked to camouflage in diverse habitats, enhancing crypsis among leaf litter and vegetation.^[12] Sexual dimorphism is pronounced in several anatomical features. Body size dimorphism varies across populations, with females often equal to or larger than males in snout-vent length. Males have a thicker tail base, broader heads and more robust jaws relative to SVL, adaptations potentially tied to intra-male competition and prey handling.^[15]^[16]^[1] These differences underscore the species' reproductive strategy and ecological role.

Coloration and polymorphism

The viviparous lizard, Zootoca vivipara, exhibits dorsal coloration primarily in shades of brown, grey, green, or black, often accented by darker longitudinal stripes or spots that aid in blending with varied terrestrial substrates. Ventral surfaces are generally paler, but show sexual dimorphism, with males displaying more vivid patterns in yellow, orange, or red tones interspersed with black spots. Female Z. vivipara demonstrate notable ventral color polymorphism, with three discrete morphs: yellow (pale yellow throat and belly), orange (bright orange ventral surfaces), and mixed (intermediate orange-yellow patterns). These morphs are stable from sexual maturity, maternally heritable, and influenced by both genetic factors—such as variations in genes like DGAT2 (involved in carotenoid metabolism) and PMEL (linked to melanin synthesis)—and hormonal regulation that correlates with behavioral differences.^[17] Reproductive outcomes vary by morph: yellow females produce smaller clutches but larger offspring, enhancing individual juvenile viability in high-density conditions; orange females lay larger clutches of smaller offspring, benefiting from low-density environments; and mixed females exhibit intermediate clutch and offspring sizes, yielding the highest overall fitness across diverse ecological contexts due to balanced trade-offs. In contrast, male coloration is less polymorphic, featuring consistent carotenoid-based ventral hues ranging from yellow to orange with melanic spots, primarily serving as signals during territorial and courtship displays. Male patterns may intensify seasonally during the breeding period and darken with age, reflecting physiological condition and competitive status. This coloration serves adaptive functions, including camouflage via dorsal patterns that match heterogeneous habitats like peatlands and forests, thereby reducing detection by predators. Ventral polymorphism in females facilitates intraspecific signaling, influencing mate choice and social interactions, while morph-specific reproductive strategies promote polymorphism maintenance through frequency- and density-dependent selection, where trade-offs in clutch size, offspring quality, and competitive ability optimize fitness under varying predation pressures and resource availability. ^[18]

Distribution and habitat

Geographic range

The viviparous lizard (Zootoca vivipara) exhibits one of the broadest geographic distributions among terrestrial reptiles, spanning much of Eurasia from the British Isles and Ireland in the west to the Pacific coast of Russia, including Sakhalin Island, and extending into Hokkaido, Japan, as well as parts of northern China (Xinjiang and Heilongjiang), Mongolia, and Kazakhstan.^[2]^[19] This vast range covers temperate, boreal, and subarctic zones across northern, western, central, and eastern Europe, as well as northern Asia.^[20] In the north, Z. vivipara reaches latitudes up to approximately 68°N in Scandinavia and Siberia, extending beyond the Arctic Circle and qualifying it as the northernmost-ranging reptile species globally.^[10]^[21] Its southern limits lie in northern Spain, northern Italy, Montenegro, and parts of the Balkans and central Asia, where populations are confined to higher elevations.^[2] Populations of Z. vivipara include several disjunct groups, particularly in mountainous regions such as the Pyrenees, Alps, and Carpathians, where isolated relict habitats support distinct subspecies like the oviparous Z. v. louislantzi in the Pyrenees (northern Spain, Andorra, southwestern France) and Z. v. carniolica in the Alps and northern Dinaric Mountains.^[2]^[22] A notable recent discovery in 2022 confirmed a lowland population in the Carpathian Basin of Hungary, representing an isolated relict occurrence in marshy habitats near Lake Fertő and the Hanság region.^[23] The species' range has remained largely stable historically, with fragmentation driven by climate fluctuations and habitat loss, but no significant expansions have been documented since 2019; its overall distribution supports a Least Concern status on the IUCN Red List due to presumed large populations and adaptability.^[19]^[24]

Habitat preferences

The viviparous lizard (Zootoca vivipara) primarily inhabits open, humid environments such as heathlands dominated by common heather (Calluna vulgaris), moorlands, grasslands with dense swards, woodland edges and clearings, and bogs.^[25]^[26] It avoids dense forests and arid regions, favoring instead humid biotopes that provide suitable moisture levels given its low resistance to desiccation.^[27]^[28] Within these habitats, the species selects microhabitats that balance exposure and shelter, preferring sunny, open patches for basking alongside nearby cover such as vegetation, rocks, or low scrub for refuge.^[29]^[30] This selection supports its thermoregulatory needs while minimizing predation risk. The lizard's viviparous reproduction enables tolerance of cool, wet climates, allowing persistence in peat bogs and heathlands even in northern latitudes where conditions are consistently damp and cold.^[31] The altitudinal range spans from sea level to 2,800 m in mountainous regions, encompassing temperate, boreal, alpine, Atlantic, and continental climates.^[32] A 2021 study highlighted climatic niche differences among clades, revealing that viviparous forms (clades C–F) occupy areas with colder temperatures and lower variability during the reproductive season (May–July), contrasting with oviparous clades (A and B) in more variable environments.^[33]

Ecology and behavior

Diet and foraging

The viviparous lizard (Zootoca vivipara) exhibits an insectivorous diet dominated by small invertebrates, with hemipterans (such as leafhoppers and cicadas), spiders (Araneae), beetles (Coleoptera), and dipterans (flies) comprising the majority of consumed prey.^[34]^[1] Other arthropods, including opilionids and lepidopteran larvae, are also taken, though ants (Formicidae) are largely avoided despite their abundance in habitats.^[34] Instances of cannibalism occur rarely, representing less than 1% of dietary items in analyzed samples.^[34] Foraging is active and diurnal, with lizards relying on visual detection and tongue flicking to sense chemical cues from potential prey, often pursuing hard-shelled or sedentary invertebrates over evasive ones. Recent studies indicate that chemoreception incurs energetic and hydric costs, influencing foraging efficiency under varying environmental conditions.^[34]^[4]^[35] Juveniles target smaller prey items (typically under 10 mm), reflecting their size limitations, while adults exhibit greater dietary diversity (14–17 operational taxonomic units versus 11–13 for immatures) and consume larger items up to 20 mm in length.^[34] Feeding ceases below approximately 27°C body temperature in natural conditions, limiting activity to warmer daylight periods.^[1] Seasonal patterns show elevated foraging rates and intake during summer months, enabling lipid accumulation in tissues for overwintering and reproduction, with lipid stores peaking prior to hibernation.^[36] Prey availability fluctuates with environmental conditions, influencing body condition and dietary breadth, as lizards adjust to shifts in invertebrate abundance across the active season (May–September).^[34] The digestive system is adapted for a high-protein invertebrate diet, featuring efficient assimilation that may under-represent soft-bodied prey in fecal analyses due to complete breakdown, and temperature-dependent gut passage times that accelerate at higher temperatures to support rapid somatic growth.^[37]

Predators and defense

The viviparous lizard (Zootoca vivipara) faces predation from a diverse array of vertebrates across its range, with juveniles experiencing particularly high vulnerability. Common predators include birds such as kestrels (Falco tinnunculus), great grey shrikes (Lanius excubitor), and corvids like magpies (Pica pica), jays (Garrulus glandarius), and carrion crows (Corvus corone), which often target lizards in open or semi-open habitats. Snakes, particularly viper species like the European adder (Vipera berus), frequently prey on both juveniles and adults, while mammals such as foxes (Vulpes vulpes), weasels (Mustela nivalis), hedgehogs (Erinaceus europaeus), and shrews (Sorex spp.) pose significant threats, especially to smaller individuals. Domestic and feral cats (Felis catus) and dogs (Canis familiaris) also contribute to mortality in human-modified landscapes.^[38]^[1]^[4]^[39] Predation imposes substantial selective pressure, with juveniles facing annual mortality rates that can reach up to 90% in their first year, much of which is attributable to predator attacks rather than other factors like environmental stress. Adults exhibit greater resilience due to increased body size and behavioral vigilance, though they still suffer notable losses from avian and mammalian predators. In farmland and forest-edge habitats, birds like shrikes demonstrate biased predation toward males, potentially linked to sex-specific activity patterns. Overall, predation accounts for a significant portion of population regulation, with estimates suggesting 20-50% of juvenile deaths directly from predators in monitored populations.^[38]^[40]^[41] To counter these threats, Z. vivipara employs a suite of anti-predator defenses, including caudal autotomy, where individuals voluntarily shed their tail to distract and escape pursuing predators; the detached tail continues to wriggle, drawing attention while the lizard flees. This mechanism is particularly effective against grasping predators like birds and mammals, though it incurs costs such as reduced locomotor performance and energy reserves, as the tail comprises up to 19% of body mass. Lizards also rely on rapid flight responses, sprinting to nearby cover like vegetation or rocks upon detecting threats, with escape tactics varying by habitat—individuals in open areas initiate flight earlier and achieve higher speeds compared to those in dense cover.^[42]^[43]^[4]^[44] Additional strategies involve crypsis through immobility and camouflage, where lizards freeze in place to blend with their surroundings, leveraging their variable dorsal patterning of spots and stripes that match substrates like leaf litter or grass. This passive defense is especially pronounced in response to chemical cues from predators, such as odors, prompting individuals to remain motionless and reduce visibility. Gravid females show heightened risk-aversion in escape behaviors, correlating with physiological state to minimize predation during vulnerable reproductive periods. These adaptations collectively enhance survival, with evolutionary pressures favoring faster escape velocities in exposed habitats. Recent research also indicates that lizards use social information from conspecifics to inform spatial decisions and potentially reduce predation risk through adjusted relocation behaviors.^[1]^[45]^[46]^[47]^[48]

Parasites and diseases

The viviparous lizard (Zootoca vivipara) harbors a range of parasites, including endoparasites such as helminths and haemogregarinid blood parasites, as well as ectoparasites like mites and ticks.^[49]^[50]^[51] Overall parasite prevalence in populations can reach approximately 40%, though this varies by parasite type and location.^[49]^[50] Endoparasites include helminths, with nematode infracommunities dominated by Oswaldocruzia filiformis (prevalence 37.9%, mean intensity 2.4 worms per infected host) and trematodes such as Plagiorchis molini (prevalence 2.2%, mean intensity 0.03).^[50] Helminth diversity is generally low, often limited to one or two species per host, correlating positively with host body size in females for O. filiformis intensity.^[50]^[52] Blood parasites, primarily haemogregarinids (e.g., Haemogregarina spp.), occur at prevalences of 39.8% in some Polish populations, with no significant differences between sexes or correlations to body size or co-occurring ticks.^[49] Cestodes are rarely reported, contributing to the depauperate helminth communities observed in this species.^[50] Recent studies (as of 2025) have identified bacterial pathogens such as Borrelia spp., Rickettsia spp., and Anaplasma spp. in Ixodes ricinus ticks infesting Z. vivipara, particularly in urban areas of Poland, highlighting the role of lizards in maintaining tick-borne disease cycles. Data on viral pathogens remain limited, with few documented cases affecting wild populations.^[53]^[54] Ectoparasites consist mainly of mites in the genus Ophionyssus (e.g., O. natricis) and ticks such as Ixodes ricinus, which infest lizards across their range.^[51]^[55] Mite loads are higher in males and individuals in poor body condition, while tick infestations show no such patterns.^[51] Ectoparasite loads negatively correlate with host density, suggesting behavioral avoidance or reduced transmission in crowded habitats rather than increased risk.^[55] Co-occurrence of mites and ticks is low (about 4%), with environmental factors mediating negative associations between them.^[51] Parasite infections can impair host health by reducing energy reserves, suppressing immune function, and increasing mortality risk in severe cases, potentially leading to decreased growth rates and fertility.^[55]^[56] For instance, high ectoparasite loads, particularly mites, are linked to elevated female mortality during late pregnancy, indirectly affecting reproductive success, though direct pregnancy failure is not consistently observed.^[56] No major epidemics of parasitic diseases have been reported in Z. vivipara populations. Prevalence and intensity of parasites exhibit regional and environmental variation; for example, mite infestations increase with altitude and vegetation cover but decrease with human disturbance and livestock grazing, while ticks show the opposite trend.^[51] In warmer, lower-elevation sites within the species' southern range, ectoparasite abundance may be higher due to extended activity seasons, though data specific to Z. vivipara are sparse compared to northern populations.^[57] Host responses to parasites include seasonal fluctuations in cellular immunity, with phytohaemagglutinin-induced swelling (a measure of immune reactivity) varying by color morph and potentially lower during periods of high reproductive effort.^[58] During hibernation, prolonged inactivity contributes to elevated parasite mortality, particularly for ectoparasites, effectively reducing loads upon emergence, though immune suppression may occur in this dormant state.^[57]

Thermoregulation

The viviparous lizard, Zootoca vivipara, is an ectotherm that relies on behavioral thermoregulation to maintain its body temperature within an optimal range of 30–35°C, primarily through basking in sunlight and shuttling between sun-exposed and shaded areas to avoid overheating. Recent research (2024) has linked these behaviors to animal personality traits, with individual differences in thermoregulatory strategy influencing ecological performance.^[59]^[60]^[61] This strategy allows the lizard to achieve preferred body temperatures of approximately 30–34°C in males and 29.5°C in gravid females during the active season, enhancing physiological performance for activities such as locomotion and foraging.^[59] In cold climates, Z. vivipara exhibits remarkable freeze tolerance, supercooling its body fluids to as low as -3.5°C without ice formation and surviving tissue freezing down to -3°C, facilitated by glucose as a cryoprotectant and the presence of ice-nucleating proteins that control the freezing process.^[62] During hibernation, individuals endure prolonged subzero exposure, remaining supercooled in dry soil for weeks before freezing for up to two months at temperatures of -3 to -10°C, with survival rates of about 21% in simulated Siberian conditions. Seasonal thermoregulation patterns reflect the challenges of post-hibernation recovery, with males emerging infertile for approximately two weeks due to the time required for sperm maturation under low ambient temperatures.^[63] A 2016 study on Siberian populations highlighted how groundwater seepage moderates hibernation site temperatures in spring, preventing premature freezing and enabling synchronized emergence as soil warms to 0°C. Northern adaptations in Z. vivipara include shorter activity periods limited by extended winters and a heavy reliance on microclimates, such as south-facing slopes or vegetated refuges, to facilitate basking and maintain body temperatures despite low thermal quality environments.^[64] These behaviors come at a time cost, as lizards prioritize precise thermoregulation over other activities in subarctic habitats.^[64]

Reproduction

Reproductive modes

The viviparous lizard (Zootoca vivipara) displays intraspecific variation in reproductive modes, with viviparity predominant in northern populations inhabiting cold climates and oviparity in southern populations in warmer regions.^[65] Viviparity involves the retention of eggs within the female's reproductive tract until fully developed offspring are born live, typically north of approximately 50°N latitude, while oviparity entails the deposition of eggs that undergo external incubation and hatching.^[66] In hybrid zones, such as those in the Pyrenees and western Europe, intermediate or mixed reproductive strategies occur, with recent genetic analyses confirming limited gene flow between parities despite occasional hybridization.^[11] This geographic partitioning of modes reflects adaptations to environmental conditions, with viviparity enabling embryonic protection and accelerated development in cooler areas with shorter activity seasons.^[10] In viviparous populations, fertilized eggs are retained internally for 3–4 months during gestation, during which embryos develop to an advanced stage (Dufaure and Hubert stage 40) before live birth in late summer.^[1] Nutrient provisioning is primarily lecithotrophic, relying on yolk reserves, but limited placental transfer of nutrients, water, and ions occurs via specialized extraembryonic membranes forming a placenta-like structure, including the chorioallantoic placenta for gas exchange and minor maternal contributions.^[67] This internal incubation allows females to regulate embryonic temperature through basking, potentially enhancing offspring viability in cold environments.^[68] In contrast, oviparous females lay soft-shelled eggs in moist substrates after about 1–2 months of internal development, with external hatching occurring after 4–6 weeks of incubation, depending on temperature, after which yolk-dependent neonates emerge independently.^[69] The evolutionary origins of these modes in Z. vivipara involve a single origin of viviparity followed by reversals to oviparity, based on phylogenetic analyses of mitochondrial and nuclear markers.^[70] This lability is linked to climatic pressures, where viviparity likely evolved convergently in response to cold conditions to shorten the external developmental period and mitigate risks from low temperatures.^[71] Recent transcriptomic studies (as of 2025) highlight Z. vivipara as a model for studying reproductive mode evolution in squamates, identifying differentially expressed genes (e.g., NOS1, MALL, CLCN2) and alternative splicing events involved in viviparity, with shared features across viviparous lineages.^[72] Viviparity confers advantages in boreal habitats but incurs higher maternal costs, including elevated locomotor and metabolic expenses during pregnancy compared to oviparity.^[73]^[74] Brood size tends to be smaller in viviparous forms, averaging 5–8 offspring, compared to 6–12 in oviparous ones, reflecting trade-offs in reproductive investment.^[75]

Mating system

The viviparous lizard (Zootoca vivipara) exhibits a promiscuous mating system characterized by polygyny and polyandry, where males mate with multiple females and females accept copulations from several males during the breeding season.^[76] This system promotes sperm competition, as females store sperm from different males, influencing male reproductive strategies focused on maximizing mating opportunities rather than exclusive pair bonds.^[77] Courtship begins shortly after hibernation, typically in April to May, with males actively seeking receptive females signaled by chemical cues such as pheromones in femoral gland secretions.^[78]^[79] Males initiate displays involving rapid push-ups—raising and lowering the body—and head-bobbing movements to advertise fitness and attract females, often incorporating throat coloration (e.g., orange, yellow, or white morphs) as a visual signal during these behaviors.^[80] Females exercise mate choice by responding preferentially to vigorous displays from high-quality males, rejecting others through avoidance or aggression.^[81] Male-male competition is a key component of mate acquisition, with territorial males engaging in aggressive encounters that escalate to biting and wrestling to establish dominance over resources and potential mates.^[82] Larger-headed males, exhibiting sexual dimorphism in head size relative to body length, consistently win these contests and grasp females more effectively during attempted matings, enhancing their reproductive success.^[83] This dimorphism underscores the role of intrasexual selection in shaping male morphology for competitive advantage in the promiscuous context.^[83]

Life history traits

Sexual maturity in the viviparous lizard (Zootoca vivipara) is typically reached in the second year of life, with individuals attaining a snout-vent length (SVL) greater than 40 mm.^[84] Males generally mature at age 2, with a minimum SVL of 44–46 mm, while females may require 2–3 years and exhibit a broader adult SVL range of 45.6–77.3 mm (mean 59.3 mm); viviparous females tend to attain larger body sizes than oviparous ones, contributing to greater sexual size dimorphism (as of 2024).^[85]^[74] However, males experience a post-hibernation delay in fertility, remaining infertile for approximately two weeks after emergence in April, as spermatozoa in the testes become functional only after transfer to the epididymis in early May.^[86] Fertilization is internal, occurring via the male's hemipenes during copulation shortly after female emergence from hibernation.^[87] Females can store sperm in their oviducts for extended periods, with viable spermatozoa preserved for months, enabling delayed fertilization.^[88] Brood size varies from 2 to 14 young, with an average of 6–8; viviparous populations tend to produce smaller litters compared to oviparous forms but invest more per offspring.^[85]^[75] Neonate SVL measures 17–22 mm at birth, independent of maternal litter manipulation.^[89] In the wild, Z. vivipara has a lifespan of 5–6 years, though some individuals survive up to 8 years; captive conditions can extend this to around 10 years.^[4] Annual adult survival averages approximately 50%, with females at 55% and males at 30%.^[90] Growth is rapid during the first year, driven by high prey availability and environmental factors like precipitation, but slows after maturity as energy shifts toward reproduction.^[91]^[87] Viviparity supports higher offspring survival in cold climates by enabling internal development.^[75]

Conservation

Status and threats

The viviparous lizard (Zootoca vivipara) is classified as Least Concern (LC) on the IUCN Red List globally, a status assigned in 2009 due to its extensive distribution across Eurasia, tolerance of diverse habitats, and presumed large population size. However, in certain regions such as the United Kingdom, populations are declining and the species is recognized as a priority under the UK Post-2010 Biodiversity Framework, reflecting localized vulnerabilities despite the overall secure global assessment.^[92] Primary threats to Z. vivipara stem from anthropogenic activities, including habitat fragmentation and loss driven by agricultural expansion, urbanization, and tourism development, which disrupt suitable moorland, heathland, and forest edge environments.^[93] Climate change poses an additional risk by altering climatic niches, particularly during the reproductive period; a 2021 study highlighted niche differences among clades, with viviparous populations in more stable but warming conditions potentially facing shifts that affect reproduction and survival.^[10] Regionally, southern-edge populations, such as those in clade A at the distribution's limit, exhibit heightened vulnerability to warming temperatures, contributing to observed declines in these areas.^[10] On islands within its range, competition from invasive species like the wall lizard (Podarcis muralis) exacerbates pressures, as native Z. vivipara demonstrate avoidance behaviors in response to intruder scents, potentially limiting resource access.^[94] Legally, Z. vivipara receives protection under the European Union's Habitats Directive as a species of community interest requiring strict protection (Annex IV), prohibiting deliberate capture or killing across member states.^[95] It is not listed under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), indicating no international trade restrictions.^[1]

Population trends

Population densities of Zootoca vivipara vary significantly across habitats and regions, typically ranging from 150 to 250 individuals per hectare in favorable lowland and marshy areas.^[23] In some optimal lowland populations, densities can fluctuate between 920 and 1,830 individuals per hectare, while mountain populations exhibit lower values of 513 to 709 individuals per hectare.^[96] Northern and subarctic populations, such as those in tundra-like environments, maintain notably lower densities due to harsher conditions, often described as low without exceeding a few dozen individuals per hectare in monitored sites.^[97] Overall, Z. vivipara populations are considered stable across its wide Eurasian range, reflecting its adaptability and presumed large total numbers.^[1] However, local declines have been observed, particularly in the United Kingdom, where populations are suspected to be decreasing due to various pressures.^[20] Recent discoveries, including new records from 2022 in isolated Hungarian marshy relict habitats, indicate ongoing persistence in fragmented areas despite these localized reductions.^[23] Monitoring efforts have bolstered understanding of these dynamics; in Germany, Z. vivipara was designated Reptile of the Year in 2006 to promote conservation awareness and data collection.^[7] Citizen science platforms like iNaturalist contribute to range stability assessments, with observations confirming the species' broad distribution and least concern status without evidence of widespread contraction.^[9] Home range sizes for Z. vivipara typically span 500 to 1,700 m², with males averaging larger areas (e.g., 584–1,692 m²) than females (e.g., 539–1,059 m²) across studied populations, and these vary inversely with local density and prey availability.^[1] Additionally, viviparous clades demonstrate climate resilience by occupying niches with reduced temperature and precipitation variability during the reproductive period (May–July), enabling maintenance in stable but challenging environments.^[10] Habitat loss is accelerating some declines, particularly in anthropogenically altered landscapes.^[20]

References

[1]
Zootoca vivipara (Viviparous Lizard) - Animal Diversity Web
Viviparous lizards are the only lizard species that is known both to give live birth and to lay eggs. The reasons for differences in reproductive method between ...
[2]
Zootoca vivipara (LICHTENSTEIN, 1823) - The Reptile Database
Viviparous and oviparous. Lacerta vivipara is ovoviviparous throughout most of its range, but oviparous in the extreme southwest portion (Heulin et al., 1989).
[3]
https://www.iucnredlist.org/species/61741/49741947
[4]
Common lizard | Wildlife Online
Colour/Appearance: These are short-legged lizards, presenting with a small, rounded head and a thick neck and tail, which tapers to a point. It is common to ...Missing: scientific | Show results with:scientific
[5]
http://reptile-database.reptarium.cz/species?genus=zootoca&species=vivipara
[6]
[PDF] Synonymy and nomenclatural history INTRODUCTION - Zobodat
'"Lacerta vivipara Jacquin, 1787" had therefore not become an available name (Art. 11.5 ICZN). 3.2. The search for the correct species name. According to the ...
[7]
Zootoca vivipara (LICHTENSTEIN, 1823) - The Reptile Database
Zootoca vivipara (LICHTENSTEIN, 1823) ; Common Names, E: Viviparous Lizard, European common lizard. G: Waldeidechse Croatian: živorodna gušterica. Russian: ...
[8]
Zootoca - Mindat
Jul 15, 2025 · Both "Zootoca" and "vivipara" mean "live birth," in Greek and Latin respectively. It was called Lacerta vivipara until the genus Lacerta was ...Missing: etymology | Show results with:etymology<|separator|>
[9]
Viviparous Lizard (Zootoca vivipara) - iNaturalist
The viviparous lizard or common lizard, Zootoca vivipara (formerly Lacerta vivipara), is a Eurasian lizard. It lives farther north than any other species of ...
[10]
Climatic niche differences among Zootoca vivipara clades with ...
Jun 29, 2021 · Analyses based on the climates during the reproductive period show that viviparous clades inhabit sites with less variable temperature and precipitation.
[11]
Genetic and ecological data reveal species boundaries between ...
Jul 1, 2015 · We studied here two lineages of the common lizard Zootoca vivipara that display different reproductive mode (the viviparous Z. v. vivipara and ...Missing: splits | Show results with:splits
[12]
Variation in body size and sexual size dimorphism in the most ...
May 6, 2020 · Zootoca vivipara is a small (adult snout‐vent length 40–80 mm), ground‐dwelling, insectivorous, heliothermic lizard. Compared to most other ...
[13]
Body Size Structure and Sex Ratio in a Population of the Common ...
Jul 28, 2022 · There was significant sexual size dimorphism (males were smaller in body length) ... sexual dimorphism in head size in the lizard Zootoca vivipara:.Missing: form | Show results with:form
[14]
[PDF] Limb malformation and tail bifurcation in sand lizards (Lacerta agilis ...
Dec 8, 2017 · Tail autotomy. (tail-shedding) is a major anti-predator strategy in ... E). Common lizard (Zootoca vivipara) female with a double tail. F ...
[15]
Evolutionary maintenance of sexual dimorphism in head size in the ...
Aug 7, 2025 · In lacertid lizard, males generally have a relatively longer snout-vent length (SVL) than females and males have generally relatively larger ...
[16]
Reproduction and morphology of the common lizard (Zootoca ...
The common lizard, Zootoca vivipara (Lichtenstein, 1823), shows high variation in life histories and morphology across its range, which comprises almost the ...Missing: subspecies list geography
[17]
Sexual Dimorphism and Female Reproduction in Lacerta vivipara in ...
Females were larger than males in both snout-vent length (SVL) and pelvic width. The smallest sexually reproductive female was 80 mm SVL, whereas the ...
[18]
https://doi.org/10.1111/brv.12656
[19]
https://www.researchgate.net/publication/289540131_Zootoca_vivipara
[20]
(PDF) Zootoca vivipara - ResearchGate
Zootoca vivipara is listed as Least Concern in view of its wide distribution, tolerance of a broad range of. habitats, presumed large population, ...
[21]
[PDF] Zootoca vivipara, Viviparous Lizard - lacerta.de
Jun 30, 2009 · In Europe it occurs as scattered © The IUCN Red List of Threatened Species: Zootoca vivipara – published in 2010. http://dx.doi.org/10.2305/ ...
[22]
[PDF] How the most northern lizard, Zootoca vivipara, overwinters in Siberia
Abstract The common lizard Zootoca vivipara has the largest range of all the terrestrial reptiles which includes the subarctic regions of the Palaearctic.
[23]
Phylogeography and conservation of the populations of Zootoca ...
Aug 6, 2025 · This study aims to elucidate the geographic distribution, phylogeography and conservation priority of the oviparous subspecies, Zootoca vivipara carniolica.
[24]
New record of the viviparous lizard Zootoca vivipara (Jacquin, 1787 ...
Jan 13, 2022 · The viviparous lizard Zootoca vivipara (Jacquin, 1787) is a terrestrial reptile species with the largest distribution area on Earth, which ...Missing: 1785 | Show results with:1785
[25]
[PDF] European Red List of Reptiles - IUCN Portals
The. Red List provides taxonomic, conservation status, and distribution ... Zootoca vivipara. LC. LC. SQUAMATA. SCINCIDAE. Ablepharus budaki. LC. LC. SQUAMATA.
[26]
(PDF) Reptile habitat preference in heathland: Implications for ...
Aug 6, 2025 · The viviparous lizard preferred habitats with common heather and purple moor grass. The impact of current nature management on the maintenance ...
[27]
Distribution of the common lizard (Zootoca vivipara) and landscape ...
Aug 5, 2025 · ... Zootoca vivipara is a ground-dwelling species that occupies bogs, rocky outcrops, old stone walls, sand dunes and are frequently found ...Missing: arid | Show results with:arid<|separator|>
[28]
Variation of Reproductive Traits and Female Body Size in the Most ...
Zootoca vivipara is a small (adult snout-vent length 41–77 mm), ground-dwelling, insectivorous, heliothermic lizard. It occupies nearly the whole Europe and ...
[29]
(PDF) On the importance of tree stand composition and age in forest ...
Aug 9, 2025 · The species avoided wetland forests. Zootoca vivipara preferred pine-dominated stands, and avoided deciduous stands. Data showed a negative ...Missing: arid | Show results with:arid
[30]
Common lizard microhabitat selection varies by sex, parity mode ...
Sep 4, 2023 · The common lizard (Zootoca vivipara) has egg-laying and live-bearing lineages and displays a variety of dorsal patterns and colouration. How ...
[31]
(PDF) The importance of habitat resistance for movement decisions ...
Conclusions: Our results highlight the importance of understanding the habitat resistance for movement patterns, with humid habitats with covering vegetation ...
[32]
Northern boundary of Z. vivipara range (line) and the permafrost area...
The common lizard Zootoca vivipara has the largest range of all the terrestrial reptiles which includes the subarctic regions of the Palaearctic. The species ...
[33]
Phylogeographic Substructuring in the Southernmost Refugium of ...
May 10, 2024 · Some European populations are recorded at very high elevations (up to 2800 ... Zootoca vivipara [41]. Viviparity in this species evolved during ...
[34]
Climatic niche differences among Zootoca vivipara clades with ... - NIH
Jun 29, 2021 · It inhabits temperate, boreal, alpine, Atlantic and continental climates [29] and altitudes from sea level up to over 2400 m above sea level. It ...Missing: preferences | Show results with:preferences
[35]
Diet of the Viviparous lizard Zootoca vivipara (Lichtenstein, 1823 ...
Aug 10, 2025 · vivipara is an active forager. Statistically significant differences between immatures and adults were found as adults showed more diverse diet.
[36]
Storage lipids in the lizard Lacerta vivipara: a quantitative study
Lipids in various tissues of Lacerta vivipara were measured at three times of the year: immediately after hibernation, mid-season, and immediately prior to ...
[37]
[PDF] Diet of the Viviparous lizard Zootoca vivipara (Lichtenstein, 1823 ...
Some authors argue that soft-bodied in- vertebrates may be absent or under-represented, because of complete assimilation in the digestive tract (Carretero 2004,.
[38]
[PDF] predators of the common lizard (zootoca vivipara) in a habitat of ...
A review of anti-predatory strategies employed by Lacertidae can be found in Bauwens & Thoen. (1981) and Gramentz (1995). The lizards fall prey to invertebrates ...
[39]
Common Lizard (Zootoca vivipara) - Woodland Trust
Timid, lightning-quick and sun-worshipping. The common lizard basks in the warmth of the sun along woodland edges, sunny glades and rides.Missing: biology | Show results with:biology
[40]
(PDF) Predators of the common lizard (Zootoca Vivipara) in a habitat ...
Feb 1, 2016 · The studies included, among others, identifying vertebrate predators of this species. Three amphibian species, 2 reptile species, 21 birds and ...
[41]
Do males pay more? A male-biased predation of common lizard ...
Jun 11, 2019 · We have studied predation of the common lizard (Zootoca vivipara) by the great grey shrike (Lanius excubitor) in farmland habitats in western ...
[42]
Tail loss and thermoregulation in the common lizard Zootoca vivipara
Tail autotomy in lizards is an adaptive strategy that has evolved to reduce the risk of predation. Since tail loss reduces body mass and moving ...
[43]
Does tail autotomy affect thermoregulation in an accurately ...
Jul 7, 2015 · Tail autotomy is an antipredatory defense that allows lizards to escape predator attacks by shedding their tails.
[44]
Influence of habitat structure on the escape tactics of the lizard ...
This suggests that misleading the predator is also crucial to escaping successfully. Escape responses were independent of ambient temperature. Lizards showed ...
[45]
Common lizard - Game and Wildlife Conservation Trust
About 10-15cm in length, they are quite variable in colour and their skin is covered in tiny scales, forming patterns of spots and stripes to camouflage them ...
[46]
Common Lizard (Zootoca vivipara) - Flora and Fauna of the UK
Nov 18, 2024 · Habitat loss is the primary concern, particularly in areas where heathlands, grasslands, and other natural habitats are being converted to ...
[47]
Sex‐ and state‐dependent covariation of risk‐averse and escape ...
Dec 11, 2023 · The aim of the present study was to examine the covariation of risk-aversion and escape behavior in the common lizard Zootoca vivipara.
[48]
Blood parasites in two co-existing species of lizards (Zootoca ...
Jul 27, 2010 · Haemogregarinid blood parasites were found to be the common parasite of both lizard species in studied locality with prevalence 39.8 (95% CL, ...
[49]
[PDF] Host-parasite relationships of Zootoca vivipara (Sauria
In this study we analyse the prevalence, intensity and helminth diversity of parasites of common lizard in an alpine meadow habitat, specifically addressing the ...
[50]
Environmental variation mediates the prevalence and co-occurrence ...
Oct 22, 2019 · We found the probability of mite infestation increased with altitude and vegetation cover, but decreased with human disturbance and presence of livestock.
[51]
Host-parasite relationships of Zootoca vivipara (Sauria: Lacertidae ...
The helminths infesting the common lizard, Zootoca vivipara (Jacquin, 1787), were studied with special attention to the relations between the number of ...
[52]
Article - Nature Conservation Research - Фонд «Медвежья Земля»
We found only two species of helminths in Zootoca vivipara. Most of the parasites (16 species) are distributed through the Palaearctic. We found one species, ...
[53]
Host density and ectoparasite avoidance in the common lizard ...
In this study we tested the hypothesis regarding ectoparasites as a cost of living in crowded habitats in the common lizard (Lacerta vivipara).
[54]
[PDF] Parasites, But Not Palpation, are Associated With Pregnancy Failure ...
Although parasitic infestations are linked with morbidity and mortality, their effects on reproductive output are less clear. Reproductive output of European.
[55]
Opposed elevational variation in prevalence and intensity of ...
Our findings imply that, in a scenario of climate warming, populations of lizards at high elevation may face increased abundance of ectoparasites, accompanied ...<|separator|>
[56]
Seasonal changes in parasite load and a cellular immune response ...
May 9, 2010 · In this study we investigate morph specific variation in parasite load and cellular immune response (induced by a Phytohaemagglutinin, PHA ...
[57]
Global changes explain the long-term demographic trend of the ...
Zootoca vivipara's effective population size increased since 2.3 million years ago and started to increase steeply and continuously from 0.531 million years ago ...
[58]
Climate dependent heating efficiency in the common lizard - PMC
Jul 16, 2020 · Accurate thermoregulation however entails costs. First, behavioral thermoregulation, by shuttling between basking sites and cooler patches ...
[59]
Supercooling, ice inoculation and freeze tolerance in the ... - PubMed
European common lizards can supercool to -3.5°C, freeze with ice contact, but tolerate freezing of tissues to -3.0°C, and may use glucose as a cryoprotectant.Missing: Zootoca | Show results with:Zootoca
[60]
Experimental evidence that sperm maturation drives protandry in an ...
Early emergence from hibernation by males, relative to females, thus increases the male's chance of fertilising eggs and later emergence from hibernation by ...Missing: post- | Show results with:post-
[61]
(PDF) To thermoconform or thermoregulate? An assessment of ...
Aug 6, 2025 · These results suggest that Z. vivipara regulated body temperature at the expense of time that could be devoted to other activities.<|separator|>
[62]
Phylogeography and conservation of the populations of Zootoca ...
The lizard Zootoca vivipara has both oviparous and viviparous populations which belong to distinct clades. This study aims to elucidate the geographic ...
[63]
Biogeography of Lacerta (Zootoca) vivipara: reproductive mode and ...
Jun 30, 2006 · Lacerta (Zootoca) vivipara, has allopatric oviparous and viviparous populations viviparity is observed from central France and the British ...
[64]
Extraembryonic membrane development in a reproductively bimodal ...
We studied development of the extraembryonic membranes and placentation in the reproductively bimodal lizard Lacerta vivipara because the influence of ...
[65]
Potentially adaptive effects of maternal nutrition during gestation on ...
Dec 15, 2011 · However, in some species, viviparity may also allow extended and more refined control of nutrient transfer through the placenta, providing a ...
[66]
[PDF] Further evidence of the existence of oviparous populations of ...
This might explain that the incubation duration of the. French sample of eggs kept at 22.5 °C, which averaged. 28.6 ± 1.8 days (n = 23, range: 27–33 d), was ...
[67]
Multiple origins of viviparity, or reversal from viviparity to oviparity ...
Jan 17, 2006 · Our results show that viviparous populations are not monophyletic, and that several evolutionary transitions in parity mode have occurred.
[68]
Early origin of viviparity and multiple reversions to oviparity in ...
Viviparity has putatively evolved 115 times in squamates (lizards and snakes), out of only ~ 140 origins in vertebrates, and is apparently related to colder ...
[69]
Understanding the evolution of viviparity using intraspecific variation ...
Apr 14, 2025 · Here we explore the biology and evolution of transitional forms of pregnancy that are midway between the ancestral state of oviparity (egg‐laying) and the ...
[70]
Differential reproductive investment in co-occurring oviparous and ...
May 6, 2019 · All lizards were weighed using a smart weigh high precision scale (to the nearest 0.001 g) and measured for snout-vent length (SVL) and tail ...
[71]
Female choice for heterozygous mates changes along successive ...
Here, we examined sequential mate choice in the common lizard Zootoca vivipara. The mating system of this species is moderately polygamous: both males and ...Missing: promiscuous | Show results with:promiscuous
[72]
Sperm competition in squamate reptiles - PMC - NIH
In the European common lizard (Zootoca vivipara), females take advantage of ... male to mate gained paternity share as the mating interval increased [34].
[73]
[PDF] Pheromones and Chemical Communication in Lizards - lacertilia.de
For example, in the common lizard, Zootoca vivipara(Lacertidae). (formerly Lacerta vivipara), the lipids in femoral secretions would oxidize very quickly ...
[74]
Synchronization of Spring Molting with the Onset of Mating Behavior ...
Aug 6, 2025 · ... Zootoca vivipara. We test whether the timing of emergence affects sperm maturation and mating success, to disentangle among proposed ...
[75]
https://pmc.ncbi.nlm.nih.gov/articles/PMC6535419/
[76]
Male ultraviolet reflectance and female mating history influence ...
Here, we investigated female mate preference based on male UV coloration in the common lizard Zootoca vivipara, in which males display conspicuous UV coloration ...
[77]
[PDF] Function and evolution of multiple signals in processes of sexual ...
of displays and behaviors, such as biting and wrestling, in case of a direct fight between two ... male quality in the lizard Zootoca vivipara (Squamata: ...
[78]
Evolutionary maintenance of sexual dimorphism in head size in the ...
Feb 28, 2006 · Zootoca vivipara is a small lizard that shows sexual dimorphism in head size. Males have larger heads than females of the same body size.Missing: width length
[79]
[PDF] A hypomelanistic common lizard (Zootoca vivipara) from the Alps
Jun 24, 2022 · Here, we report an unusual hypomelanistic or green morph of the Eurasian common lizard, Zootoca vivipara, observed in the Piedmont region of ...
[80]
[PDF] SOME ASPECTS OF REPRODUCTIVE BIOLOGY OF Zootoca ...
Fig. 1. Number of females (%) of viviparous lizard, Zootoca vivipara with the different brood size (n = 106, Tomsk area). by 1.4 times lower (Table 1).
[81]
[PDF] REPRODUCTIVE CYCLE IN A PYRENEAN OVIPAROUS ...
The Common Lizard, Zootoca vivipara, is a small ground-dwelling lacertid with a very wide distribution range (from northern Spain to Japan) living under ...Missing: disjunct relict habitats
[82]
Experimental litter size reduction reveals costs of gestation and ...
Jun 29, 2011 · ... Zootoca vivipara. To this end, we surgically removed one of the ... Storage lipids in the lizard Lacerta vivipara: a quantitative study.
[83]
[PDF] Reproductive activity of Lacerta agilis and Zootoca vivipara (Reptilia
Males of both species emerge from hibernation 10-15 days earlier than females. The emergency from hibernation of the first breeding males and females of L. ...Missing: post- | Show results with:post-
[84]
[PDF] A Note on the Reproduction of the Lizard Lacerta vivipara in ...
Neonate size was somewhat larger than that reported for a British population (17-. 22mm SVL; Smith, 1973), and clutch size was smaller than those of Britain ...
[85]
The common lizard (Zootoca vivipara, anciently Lacerta vivipara)
The common lizard belongs to the single-species genus Zootoca (from the Greek 'to give birth'). ... The species gives birth to an average clutch of five (range 1– ...Missing: etymology | Show results with:etymology
[86]
Age-dependent effects of moderate differences in environmental ...
Oct 29, 2019 · Here we experimentally tested whether and how changes in the predictability of precipitation affect growth, reproduction, and survival of common lizard Zootoca ...
[87]
Common Lizard - Froglife
Common Lizard (Zootoca vivipara). Identification, Adults up to 15 cm in length (including tail). Males have a larger head and slimmer body than females, and ...
[88]
Viviparous Lizard - Facts, Diet, Habitat & Pictures on Animalia.bio
The Viviparous lizardn(Zootoca vivipara) is a Eurasian lizard that lives farther north than any other species of non-marine reptile.Missing: scientific | Show results with:scientific
[89]
Response behaviour of native lizards and invading wall lizard to ...
Our results suggest a variable response of native species to the scent of P. muralis, from an avoidance response by Z. vivipara that mirrors patterns of ...
[90]
species of lizard (lacerta vivipara) - jstor
Densities fluctuated between 513 and 709 in- dividuals/ha in the mountain population at Gabas and between 920 and 1830 individuals/ha in the lowland population ...
[91]
[PDF] Zootoca vivipara in the subarctic
There are basically two strategies dealing with subzero temperatures in lizards: supercooling and freeze tolerance, and Z. vivipara may use both (Grenot et al.