Re-visiting phylogenetic and taxonomic relationships in the genus Saga (Insecta: Orthoptera)

PLoS One. 2012;7(8):e42229. doi: 10.1371/journal.pone.0042229. Epub 2012 Aug 10.

Abstract

Twelve of the 13 bushcricket species of the Saga genus are bisexuals and diploids, except the parthenogenetic and tetraploid bush cricket, Saga pedo. Despite a continuous research effort stretching through the 1900s, the taxonomic relationships of the Saga species are still disputed. In this study, our primary aim was to reveal natural relationships of the European Saga species and three of their Asian relatives, with special attention to the problematic taxonomy of two subspecies: S. campbelli campbelli and S. c. gracilis. Following a phylogenetic analysis of eight species, a comprehensive study was carried out on the above three taxa by using acoustic and morphometric approaches in parallel. Our phylogenetic data showed that European Saga species evolved from a monophyletic lineage. The geographical transitional species S. cappadocica was positioned between European and Asian lineages supporting the idea that the European Saga lineage originated phylogeographically from the Asian clade. The above results showed better agreement with the morphological data than with earlier ones based either on karyology or acoustic information only. After reviewing our data, we concluded that Saga pedo has most likely evolved from S. c. gracilis and not from S. rammei or S. ephippigera, as proposed by earlier studies. S. c. gracilis shares the same ITS2 haplotype with S. pedo, indicating that the latter could have evolved from populations of the former, probably through whole genome duplication. Based on acoustic and morphometric differences, we propose to elevate the two subspecies, S. campbelli campbelli and S. c. gracilis, to species level status, as Saga gracilis Kis 1962, and Saga campbelli Uvarov 1921. The present work sets the stage for future genetic and experimental investigations of Saginae and highlights the need for additional comprehensive analysis involving more Asian Saga species.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Nucleus / genetics
  • DNA, Mitochondrial / genetics
  • Evolution, Molecular
  • Female
  • Male
  • Orthoptera / anatomy & histology
  • Orthoptera / classification*
  • Orthoptera / genetics*
  • Orthoptera / physiology
  • Phylogeny*
  • Singing
  • Species Specificity

Substances

  • DNA, Mitochondrial

Grants and funding

This work supported by Bolyai Research Grant of the Hungarian Academy of Sciences, grant no.: DO 02-259/08 of the Ministry of Education, Youth and Science of Bulgaria, the United Nations Development Programme grant 00058373 - PIMS 3728 (Ref. RFP 79/2009), BG051PO001-3.3.04/41 (European Social Fund through the Ministry of Education, Youth and Science of Bulgaria), grant 57497 (2009-01-27) of the Ministry of Science and Higher Education of Poland and a bilateral agreement between the Bulgarian and Polish Academies of Sciences. The article was made under the project TÁMOP-4.2.2/B-10/1-2010-0025. IKR ZRt. provided a DNA extraction Kit. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.