Molecular Evolution of Satellite DNA CLsat in Lizards from the GenusDarevskia(Sauria: Lacertidae): Correlation with Species Diversity

Abstract

The structure and evolution of a satellite DNA family was examined in lizards from the genus Darevskia (family Lacertidae). Comparison of tandem units of repeated DNA (satDNA), CLsat, in all species from the genus Darevskia has shown that their variability is largely explained by single-nucleotide substitu- tions, which form about 50 diagnostic positions underlying classification of the family into three subfamilies. Maximum differences between the subfamilies reached 25%. At this level of tandem unit divergence in the sub- families, no cross-hybridization between them was observed (at 65 ° C). The individual variability within one subfamily within the species was on average 5% while the variability between species consensuses within a subfamily was 10%. The presence of highly conserved regions in all monomers and some features of their orga- nization show that satellites of all Darevskia species belong to one satDNA family. The organization of unit sequences of satellites CLsat and Agi160 also detected by us in another lizard genus, Lacerta s. str. was com- pared. Similarity that was found between these satellites suggests their relatedness and common origin. A pos- sible pathway of evolution of these two satDNA families is proposed. The distribution and content of CLsat repeat subfamilies in all species of the genus was examined by Southern hybridization. Seven species had mainly CLsatI (83 to 96%); three species, approximately equal amounts of CLsatI and CLsatIII (the admixture of CLsatII was 2-5%); and five species, a combination of all three subfamilies in highly varying proportions. Based on these results as well as on zoogeographic views on the taxonomy and phylogeny of the Darevskia species, hypotheses on the evolution of molecular-genetic relationships within this genus are advanced.