Chromosomal evolution in tortricid moths: conserved karyotypes with diverged features

PLoS One. 2013 May 24;8(5):e64520. doi: 10.1371/journal.pone.0064520. Print 2013.

Abstract

Moths of the family Tortricidae constitute one of the major microlepidopteran groups in terms of species richness and economic importance. Yet, despite their overall significance, our knowledge of their genome organization is very limited. In order to understand karyotype evolution in the family Tortricidae, we performed detailed cytogenetic analysis of Grapholita molesta, G. funebrana, Lobesia botrana, and Eupoecilia ambiguella, representatives of two main tortricid subfamilies, Olethreutinae and Tortricinae. Besides standard cytogenetic methods, we used fluorescence in situ hybridization for mapping of major rRNA and histone gene clusters and comparative genomic hybridization to determine the level of molecular differentiation of the W and Z sex chromosomes. Our results in combination with available data in the codling moth, Cydia pomonella, and other tortricids allow us a comprehensive reconstruction of chromosomal evolution across the family Tortricidae. The emerging picture is that the karyotype of a common ancestor of Tortricinae and Olethreutinae differentiated from the ancestral lepidopteran chromosome print of n = 31 by a sex chromosome-autosome fusion. This rearrangement resulted in a large neo-sex chromosome pair and a karyotype with n = 30 conserved in most Tortricinae species, which was further reduced to n = 28 observed in Olethreutinae. Comparison of the tortricid neo-W chromosomes showed differences in their structure and composition presumably reflecting stochasticity of molecular degeneration of the autosomal part of the neo-W chromosome. Our analysis also revealed conservative pattern of the histone distribution, which is in contrast with high rDNA mobility. Despite the dynamic evolution of rDNA, we can infer a single NOR-chromosome pair as an ancestral state not only in tortricids but probably in all Lepidoptera. The results greatly expand our knowledge of the genome architecture in tortricids, but also contribute to the understanding of chromosomal evolution in Lepidoptera in general.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chromosome Mapping
  • Chromosomes, Insect*
  • Comparative Genomic Hybridization
  • Evolution, Molecular*
  • Female
  • Histones / genetics
  • Karyotype*
  • Male
  • Mitosis
  • Moths / genetics*
  • Oocytes / metabolism
  • RNA, Ribosomal, 18S / genetics
  • Sex Chromosomes

Substances

  • Histones
  • RNA, Ribosomal, 18S

Grants and funding

This research was part of a Coordinated Research Project of the IAEA, Vienna (Research Agreement No. 15838). Experiments were funded by GACR 523/09/2106 and GAAV IAA600960925 grants. Additional support was provided from GAJU 137/2010/P and 059/2010/P grants. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.