Abstract <p>The results of complex studies on unisexual and bisexual (parental) species, mainly of the genus <i>Darevskia</i>, have been generalized, including allozyme, mitochondrial (mt) DNA, and nuclear microsatellite (ms) DNA analyses, combined with different molecular cytogenetic techniques and in combination with environmental factors. The present-day complex research has confirmed the concept of hybridogenetic speciation of unisexual species of lizards elaborated in 1980 and based on the three interrelated phenomena hybridization, unisexuality, and polyploidy. At the same time, the selectivity (constraints) and rarity of successful hybridization are emphasized at present. These studies have confirmed “paternal” and “maternal” species of hybrid unisexual species, some phylogenetic constraints of successful hybridization, and the roles played by “specific genome properties” and sex chromosomes. The data obtained have extended our knowledge of the genetic diversity of hybrid unisexual species and our understanding of the evolutionary plasticity of hybrid genomes and meiosis modifications, emphasizing the roles played by suboptimal environmental factors during the origin of such species. Further experiments may provide promising information concerning regular trends in the hybridogenetic speciation of unisexual species from different groups of vertebrate animals.</p>