Phylogenetic interpretation of chromosomal and nuclear-DNA-content data in the genus Blennius (Blenniidae: Perciformes)

Abstract

The haploid DNA content and karyotypes of eight species of Blennius are studied. Six species had 2n = 48, two had 2n = 46.The karyotypes of these species have been compared with those of related species of the genus and it was suggested that pericentric inversions played an important role in the evolution of their karyotypes. No sex chromosomes were morphologically identifiable in these gonochorist species. The data are discussed in connection with possible lines of evolution within the genus.

Chromosome relationships in the genus Blennius (Blenniidae Perciformes) C-banding patterns suggest two karyoevolutional pathways

“…The diploid number obtained for B. trigloides (2n--48) is not coincident with 2n=46 assigned by Cano et al (1982), but it fully agrees with that reported by Cataudella & Civitelli (1975). For the rest of the species described earlier (Cataudella & Civitelli, 1975;Cano et al, 1982), the discrepancies only involve the chromosome morphology with the peculiarity that our results indicate a relatively higher proportion of biarmed chromosomes. These differences in chromosome characterization are very often found among studies of the same species by different authors.…”

“…cannevae, B. pavo, B. ponticus incognitus, B. sanguinolentus, B. sphinx and B. trigloides. Three more species from the Mediterranean, B. gattorugine, B. ocellaris and B. pholis, were karyotypically described by Cano et aL (1982). The data shown in both reports indicate that, while the diploid number is fairly stable among the analyzed species (2n--48), there is a wide variation in the number of arms , although much of this variation may be most probably artificial, due to technical shortcomings.…”

“…The differences in NF found in specimens of Italian origin, could alternatively be justified by intraspecific chromosome polymorphisms. The karyotypic data on the genus Blennius, including the present report: Cataudella & Civitelli (1975), Cano et al (1982), Arai & Shiotsuki (1974), comprises twelve species, eleven of them showing 2n = 48 and only one 2n = 46. Despite this constancy in the 2n, the NF varies considerably (48-72).…”

“…Despite this constancy in the 2n, the NF varies considerably (48-72). If these karyotypic estimations are extended to the twenty karyotyped species of the family Blenniidae (Arai & Shiotsuki, 1973, 1974Cataudella & Civitelli, 1975;Cano et aL, 1982 and the present report), a wider range in the 2n (40-48) can be detected. Plotting the available data on a system of co-ordinates with the diploid number as abscissae and fundamental number as ordinates (Fig.…”