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 Pal orus 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, e ither in the form of monomers or formed by more complex repeating units. A preliminary phylogenetic analysis of Palorus species using the 3' end of th e mitochondrial Cytochrome Oxidase I gene shows that the five Palorus speci es have been diverging for a considerable amount of evolutionary time, with the pair P. ratzeburgii and P. genalis being the most closely related. Onl y these two taxa showed some similarity between their respective high-copy- number satellite sequences, while other satellites are mutually unrelated a nd might have originated independently. However, all the satellites have in common tertiary structure induced by intrinsic DNA curvature, a characteri stic which is conserved within the genus. Palorus major satellites were pre viously detected in the genomes of congeneric species as low-copy-number cl usters (Meutrovic et al., Mol. Biol. Evol. 15: 1062-1068. 1998). Given the divergences between the analysed species, the substitution rate deduced fro m high- and low-copy-number repeats is unexpectedly low. The presence of se quence-induced DNA curvature in all Palorus satellites and similar satellit e DNAs in the species pair P. ratzeburgii and P. genalis suggest (i) that c onstraints are at the tertiary structure; and (ii) that the satellite DNA e volutionary turnover can be dependant on the history of the taxa under stud y, resulting in retention of similar satellites in related taxa.