Prevalence of B chromosomes in Orthoptera is associated with shape and number of A chromosomes
- 136 Downloads
We analyze the prevalence of B chromosomes in 1,601 species of orthopteran insects where chromosome number and shape are known. B chromosomes have been reported in 191 of these species. Bs are not uniformly distributed among orthopteran superfamilies, with evident hotspots in the Pyrgomorphoidea (32.3% of species carrying Bs), Grylloidea (14.9%), Acridoidea (14.6%) and Tetrigoidea (14.3%). As expected under the theory of centromeric drive, we found a correlation between B chromosome presence and A chromosome shape—Bs are more frequent in karyotypes with more acrocentric A chromosomes. We also found that Bs are less common in species with high chromosome numbers and appear to be most common at the modal chromosome number (2n = 24). Study effort, measured for each genus, was not associated with B prevalence, A chromosome shape or A chromosome number. Our results thus provide support for centromeric drive as an important and prevalent force in the karyotypic evolution of Orthoptera, just as it appears to be in mammals. We suggest that centromeric drive may provide a mechanistic explanation for White’s principle of karyotypic orthoselection.
KeywordsB chromosome Centromeric drive Chromosome number Chromosome shape Insects Orthoptera
This study was supported by grants from the Spanish Ministerio de Ciencia y Tecnología (CGL2009-11917) and Plan Andaluz de Investigación (CVI-1664), and was partially performed by FEDER funds. We thank Austin Burt for advice and the referees for helpful comments on the paper.
- Burt A (1989) Comparative methods using phylogenetically independent contrasts. Oxf Surv Evol Biol 6:33–53Google Scholar
- Burt A, Trivers R (2006) Genes in conflict: the biology of selfish genetic elements. Belknap Press of Harvard University Press, CambridgeGoogle Scholar
- Darlington CD (1958) Evolution of genetic systems. Oliver and Boyd, Edinburgh and LondonGoogle Scholar
- Gregory TR (2010) Animal genome size database. http://www.genomesize.com
- Hewitt GM (1973) The integration of supernumerary chromosomes into the orthopteran genome. Cold Spring Harb Symp Quant Biol 38:183–194Google Scholar
- Hewitt GM (1979) Grasshopper and crickets. In: John B (ed) Animal cytogenetics, vol. 3: insecta 1 Orthoptera. Gebruder Borntraeger, BerlinGoogle Scholar
- Jones RN, Rees H (1982) B chromosomes. Academic Press, LondonGoogle Scholar
- Lamb JC, Riddle NC, Cheng Y-M, Theuri J, Birchler JA (2007) Localization and transcription of a retrotransposon-derived element on the maize B chromosome. Chromosom Res 15:383–398Google Scholar
- Makino S (1951) An atlas of the chromosome number in animals, 2nd edn. The Iowa State College Press, Ames (Iowa)Google Scholar
- Östergren G (1945) Parasitic nature of extra fragment chromosomes. Bot Notiser 2:157–163Google Scholar
- White MJD (1973) Animal cytology and evolution, 3rd edn. Cambridge University Press, CambridgeGoogle Scholar