Chromosome evolution in the genus Cicindela: Physical mapping and activity of rDNA loci in the tiger beetle species Cicindela littoralis and C. flexuosa
Proenca, S.J.R.; Galian, J.
Journal of Zoological Systematics and Evolutionary Research 41(4): 227-232
ISSN/ISBN: 0947-5745 DOI: 10.1046/j.1439-0469.2003.00216.x
Cicindela littoralis and Cicindela flexuosa were analysed at population level to determine the localization and activity of ribosomal genes. Fluorescence in situ hybridization (FISH), using a PCR-amplified 18S rDNA fragment as a probe, revealed the presence of polymorphism regarding the number of chromosomes with ribosomal genes as well as their localization within the genome. Nine populations of C. littoralis showed a consistent pattern of two loci located in an autosomal pair (active during spermatogenesis as shown by silver staining) and one locus located in one of the multiple X chromosomes (silent during spermatogenesis), whereas individuals from the population of Punta Entinas showed only signals in the autosomal pair, lacking the heterosomal locus. In C. flexuosa, two patterns were also observed. Nine populations showed two loci in an autosomal pair whereas individuals from the population of San Pedro del Pinatar showed the two loci located in the heterosomes (one of the multiple Xs and in the Y). The hypothesis that these two different populations may reflect a status of well-differentiated phylogenetic entities is not supported for C. littoralis after the phylogenetic analysis of a fragment of the cytochrome oxidase I gene.