engleski

Comparative study of satellite sequences and phylogeny of five species from the genus Palorus (Insecta, Coleoptera)

Major satellite sequences are analysed in the three tenebrionid beetles Palorus cerylonoides, P. genalis and P. ficicola, and compared with the ones from P. ratzeburgii and P. subdepressus reported elsewhere. All of them are A+T rich, pericentromerically located, and with lengths of about 150 bp either in the form of monomers or formed by more complex repeating units. A preliminary phylogenetic analysis of Palorus species using the 3' end of mitochondrial Cytochrome Oxidase I gene shows that the five Palorus species have been diverging for a considerable evolutionary time, being the pair P. ratzeburgii and P. genalis the most closely related. Only these two taxa showed a low similarity between their respective satellite sequences, while other satellites are mutually unrelated and might have originated independently. However, all the satellites have in common tertiary structure induced by intrinsic DNA curvature, a characteristic which is conserved within the genus. Palorus major satellites were previously detected in the genomes of congeneric species as low copy-number clusters (Meštrović et al., Mol. Biol. Evol., 1998, 15: 1062-1068). Given the divergences between the analysed species, the substitution rate deduced from high and low copy number repeats is unexpectedly low. The presence of sequence induced DNA curvature in all Palorus satellites and similar satellite DNAs in the species pair P. ratzeburgii and P. genalis suggest: i) that constraints are at the tertiary structure and ii) that the satellite DNA evolutionary turnover can be dependant on the history of the taxa under study, resulting in retention of similar satellites in related taxa.

satellite DNA; evolution; mitochondrial cytochrome oxidase I; DNA curvature

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