Lacerta vivipara

The viviparous lizard, Zootoca vivipara (formerly Lacerta vivipara), is a Eurasian lizard. It lives farther north than any other species of non-marine reptile, and most populations are viviparous (giving birth to live young), rather than laying eggs as most other lizards do. It is the only species in the monotypic genus Zootoca. Both 'Zootoca' and 'vivipara' mean 'live birth,' in Greek and Latin respectively. It was called Lacerta vivipara until the genus Lacerta was split into nine genera in 2007 by Arnold, Arribas & Carranza. Zootoca vivipara can be seen in a variety of different colours. Female Zootoca vivipara undergo colour polymorphism more commonly than males. A female lizard's display differs in ventral colouration, ranging from pale yellow to bright orange and a mixed colouration. There have been many hypothesis for the genetic cause of this polymorphic colouration. These hypothesis test for colouration due to thermoregulation, predator avoidance, and social cues, specifically sexual reproduction. Through an experiment conducted by Vercken et al., colour polymorphism in viviparous lizard is caused by social cues, rather than the other hypotheses. More specifically, the ventral colouration that is seen in female lizards is associated with patterns of sexual reproduction and sex allocation.