Evolution of Ribosomal DNA: Fifty Million Years of Recorded History in the Frog Genus rana

Abstract

Evolution of nuclear ribosomal DNA (rDNA) arrays of frogs of the genus Rana was examined among 32 species that last shared a common ancestor approximately 50 million years ago. Extensive variation in restriction sites exists within the transcribed and nontranscribed rDNA spacer regions among the species, whereas rDNA coding regions exhibit comparatively little interspecific variation in restriction sites. The most parsimonious phylogenetic hypothesis for the evolution of the group was constructed based on variation in restriction sites and internal spacer lengths among the 32 species of Rana and one species of Pyxicephalus (examined for outgroup comparison). This analysis suggests that R. sylvatica of North America is more closely related to the R. temporaria group of Eurasia than to other North American Rana. The hypothesized phylogeny also supports the monophyly of the R. boylii group, the R. catesbeiana group, the R. palmipes group, the R. tarahumarae group, and the R. pipiens complex. Furthermore, the restriction site data provide information about the evolution within and among these species groups. This demonstrates that restriction site mapping of rDNA arrays provides a useful molecular technique for the examination of historical evolutionary questions across considerable periods of time.

Cyst morphology and sequence analysis of the small subunit rDNA and ef1α identifies a novel Giardia genotype in a quenda (Isoodon obesulus) from Western Australia

“…The different regions of the ribosomal DNA provide varying levels of phylogenetically useful information. The coding regions (18S, 5.8S and 28S) are highly conserved whilst the internal and external transcribed spacers are moderately conserved (Hillis and Davies, 1986). Of particular interest is the 5′ end of the 18S gene, which has been used extensively for genotyping and identifying isolates of Giardia.…”

Identification of Miscellaneous Peptides from the Skin Secretion of the European Edible Frog, Pelophylax kl. Esculentus

“…Due to the development of molecular techniques, especially those that can provide comparisons of the nucleotide sequences of orthologous genes, new phylogenetic analysis of relationships between species has been made possible as an addition to the classic approach of using such aspects as the fossil record and morphological characteristics. Moreover, this improved understanding of amphibian evolutionary history should be more accurate, easier to understand and hence be more commonly accepted [22,23]. …”

Genetic differences betweenTropilaelaps clareaeandTropilaelaps koenigerumin Thailand based on ITS and RAPD analyses

“…Polymorphism of ITS is useful and has been widely used to differentiate closely related organisms, particularly at an interspecific level (Hillis and Davis, 1986;Hillis and Dixon, 1991;Odorico and Miller, 1997). However, several studies have utilized ITS sequences for intraspecific genetic analysis in invertebrates, for instance, determination of the North American tiger beetle, Cicindela dorsalis phylogeny (Vogler and DeSalle, 1994) and examination of concerted evolution and molecular drive in the black fly, Simulium damnosum (Tang et al, 1996).…”