Chromosomal evidence for the double origin of viviparity in the European common lizard, Lacerta (Zootoca) vivipara

Abstract The results of a chromosomal analysis conducted in a relict, viviparous, Hungarian (Ocsa) population of L. vivipara, show that viviparity independently arose in this population. Chromosome characteristics of Ocsa, namely females displaying 2n=36 chromosomes with a ZW sex chromosome system and W shaped as microchromosome, are peculiar to carniolica, an early diversifying clade including oviparous population, and different both from oviparous Pyrenean + Aquitainean populations and viviparous Centroeuropean + Eastern populations, whose females possess 2n=35 chromosomes with a Z(1)Z(2) W sex chromosome system, and W shaped as macrochromosomes.