Triploid hybrid formation in sympatric populations of sexual <i>Darevskia portschinskii</i> and parthenogenetic <i>D. dahli</i>

Abstract This work represents the first comprehensive study of triploid hybrids between the parthenogenetic rock lizard Darevskia dahli and its paternal species Darevskia portschinskii in newly discovered sympatric areas in Armenia. Cytogenetic, genetic, and morphometric analyses revealed that these hybrids are triploid, containing 57 chromosomes. They display intermediate scalation and differ from the parental species by their bright dorsal coloration and a distinct dark vertebral stripe formed by merged spots. The size of erythrocytes of triploids was significantly greater than that of the diploid parents. Triploids shared allelic variants of microsatellite loci inherited from both parental species. Of the nine captured hybrids, eight were sterile females with reduced ovaries, and one laid a single egg. These findings provide the first complex evidence of naturally occurring triploid hybrids between this pair of rock lizard species, which were previously hypothesized only from morphological traits and indicate their potential role in speciation through hybridization.