Document Type
Article
Department/Program
Biology
Journal Title
American Journal of Botany
Pub Date
2016
Volume
103
Issue
7
First Page
1272
Abstract
PREMISE OF THE STUDY: Hybridization between diploids and tetraploids can lead to new allopolyploid species, often via a triploid intermediate. Viable triploids are often produced asymmetrically, with greater success observed for "maternal-excess" crosses where the mother has a higher ploidy than the father. Here we investigated the evolutionary origins of Mimulus peregrinus, an allohexaploid recently derived from the triploid M. xrobertsii, to determine whether reproductive asymmetry has shaped the formation of this new species. METHODS: We used reciprocal crosses between the diploid (M. guttatus) and tetraploid (M. luteus) progenitors to determine the viability of triploid M. xrobertsii hybrids resulting from paternal-vs. maternal-excess crosses. To investigate whether experimental results predict patterns seen in the field, we performed parentage analyses comparing natural populations of M. peregrinus to its diploid, tetraploid, and triploid progenitors. Organellar sequences obtained from pre-existing genomic data, supplemented with additional genotyping was used to establish the maternal ancestry of multiple M. peregrinus and M. xrobertsii populations. KEY RESULTS: We found strong evidence for asymmetric origins of M. peregrinus, but opposite to the common pattern, with paternal-excess crosses significantly more successful than maternal-excess crosses. These results successfully predicted hybrid formation in nature: 111 of 114 M. xrobertsii individuals, and 27 of 27 M. peregrinus, had an M. guttatus maternal haplotype. CONCLUSION: This study, which includes the first Mimulus chloroplast genome assembly, demonstrates the utility of parentage analysis through genome skimming. We highlight the benefits of complementing genomic analyses with experimental approaches to understand asymmetry in allopolyploid speciation.
Recommended Citation
Vallejo-Marin, Mario; Lee, Michelle Yuequi; Cooley, Arielle M.; and Puzey, Joshua R., Strongly asymmetric hybridization barriers shape the origin of a new polyploid species and its hybrid ancestor (2016). American Journal of Botany, 103(7), 1272-1288.
https://doi.org/10.3732/ajb.1500471
DOI
https://doi.org/10.3732/ajb.1500471