Phylogenetic relationships among Brazilian Biomphalaria species (Mollusca: Planorbidae) based upon analysis of ribosomal ITS2 sequences

Abstract

In spite of their abundance, widespread distribution and medical importance, the phylogenetic relationships among Biomphalaria snails have received relatively little attention. We have collected and studied 29 populations of snails obtained from different localities from Brazil. We have sequenced the ribosomal DNA second internal transcribed spacer (ITS2) from the following Biomphalaria species: B. glabrata, B. tenagophila tenagophila, B. occidentalis, B. straminea, B. peregrina, B. kuhniana, B. schrammi, B. amazonica, B. oligoza, B. intermedia and an outgroup species Helisoma duryi. The sequence from each species is unique. Three different methods of phylogenetic reconstruction were used (distance, maximum parsimony and maximum likelihood). The resulting phylogenetic trees obtained by these methods basically support current systematic relationships based on morphological characters alone. This study demonstrates that the ITS2 region contains markers useful for identification and determination of relationships among Biomphalaria species.

Morphological and polymerase chain reaction-restriction fragment lenght polymorphism characterization of Biomphalaria kuhniana and Biomphalaria amazonica from Colombia

“…It was very clear the close relationship between B. straminea and B. kuhniana, and despite the morphological similarity of B. straminea and B. intermedia with B. peregrina, it could not be included in the complex, which is supported by the morphological information reported by Paraense (1988). Following this, Vidigal et al (2000b), through the sequencing of ITS2 of rRNA of the ten Brazilian Biomphalaria species, confirmed that B. kuhniana (from Venezuela and Brazil) is more closely related with B. straminea (from Brazil) than with B. intermedia (from Brazil). Afterwards, Dejong et al (2001) observed that, among the 23 Biomphalaria species studied, the most closely related group was that formed by B. straminea (Brazil), B. kuhniana (Dominica, Colombia and Venezuela) and B. intermedia (Paraguay).…”

“…However, the Colombian specimens showed only one of the three profiles, reported by Vidigal (2000a), which mirrors less polymorphism when compared with Brazilian specimens. The phylogenetic relationship of B. amazonica, obtained through sequencing analyses by Vidigal et al (2000b) and DeJong et al (2001), with species of the same genus, from Neotropical and African regions, showed that B. amazonica possesses high affinity with the species of the complex B. straminea.…”

“…On the other hand, the molecular profile of these snails sometimes shows three variants in the same locality (Vidigal et al 2000a). Such intraspecific variation was further studied by Vidigal et al (2000b), when the ITS2 region of Brazilian Biomphalaria snails was sequenced. Through PCR-RFLP analysis, using the same snail samples, these investigators could observe, in all trees, a polymorphism concerning the position of the three individuals (two from Amazonas and one from Mato Grosso, Brazil).…”

Preliminary studies investigating the occurrence of Biomphalaria cousini in Brazil

“…The morphological variations found in the samples analysed in this study are listed in the Table. Although Paraense (1966) previously described the morphologies of B. amazonica and B. cousini, the author emphasized the difficulties involved in such classifications, which were primarily due to high degrees of similarity between the two species. Likewise, high degrees of similarity between various Biomphalaria species were also described in phylogenetic studies performed by Vidigal et al (2000b). Those studies demonstrated that the branch with B. amazonica specimens always divided into two clusters that were similar but distinct.…”

A Multiplex-PCR approach to identification of the Brazilian intermediate hosts of Schistosoma mansoni

“…The present study was aimed at designing specific primers for Brazilian snail hosts of S. mansoni from available sequences of ITS2 of the ribosomal RNA gene, sequenced by Vidigal et al (2000a), for phylogenetic studies on Brazilian Biomphalaria.…”