A. L. Sweigart and N. H. Martin contributed equally to this study.
Patterns of nucleotide variation and reproductive isolation between a Mimulus allotetraploid and its progenitor species
Article first published online: 29 FEB 2008
© 2008 The Authors
Volume 17, Issue 8, pages 2089–2100, April 2008
How to Cite
SWEIGART, A. L., MARTIN, N. H. and WILLIS, J. H. (2008), Patterns of nucleotide variation and reproductive isolation between a Mimulus allotetraploid and its progenitor species. Molecular Ecology, 17: 2089–2100. doi: 10.1111/j.1365-294X.2008.03707.x
- Issue published online: 19 MAR 2008
- Article first published online: 29 FEB 2008
- Received 10 November 2007; revision accepted 11 January 2008
- genome duplication;
- reproductive isolation;
Here we report our characterization of a widespread, highly selfing Mimulus allotetraploid formed by interspecific hybridization between M. nasutus and M. guttatus. Nucleotide variation at two nuclear loci (mCYCA and mAP3) within and among tetraploid populations resolves two haplotype clusters for each locus: one shares near identity with sequences from M. nasutus and the other group shares substantial variation with M. guttatus. With respect to the two loci studied, each allotetraploid individual is a ‘fixed heterozygote’ carrying sequences from both clusters. Moreover, mCYCA variation is consistent with at least two evolutionary origins for the Mimulus allotetraploid. We show that the allotetraploid is strongly reproductively isolated from M. nasutus and M. guttatus; interploidy crosses produce almost no viable seeds. By extension, we infer strong triploid block and argue that Mimulus allotetraploid formation might proceed in one step via the union of unreduced gametes in an M. nasutus–M. guttatus F1 hybrid. We also discuss the potential roles of mating system and flowering asynchrony in allotetraploid establishment.