Origin and evolution of Fragaria cascadensis
Final Report Abstract
In this study, I used whole genome sequencing and target enrichment Hyb-Seq to investigate the origin and evolution of the decaploid Oregon Cascade endemic Fragaria cascadensis. With extensive sampling, I was able to show that F. cascadensis evolved repeatedly. The species has a higher genetic diversity in the southern part of its distribution range, which can be explained by range shift during glacial periods. The sampling strategy led to the discovery of nonaploid hybrids of F. cascadensis with octoploid F. virginiana subsp. platypetala in three different populations. These newly discovered hybrids prove that gene flow is possible between the sympatric taxa in the Cascade Mountains. Analyzing the plastid genome of 43 offspring samples of a controlled cross allowed to find evidence for paternal transmission of plastids in F. cascadensis and is therefore likely to be found in all North American polypoid taxa of Fragaria. This evidence proves that plastid phylogenies are not as easy to interpret as usually assumed. Future studies using the plastid genome should consider paternal transmission of plastids (and mitochondria) as possible explanation for phylogenetic patterns. The successful usage of whole plastid genomes for phylogenetic analysis in Fragaria led to further usage of this approach for Fragaria in the working group of A. Liston and will be published in the future. Additional follow-up studies are planned.
Publications
- (2018) Plastid genomes reveal recurrent formation of allopolyploid Fragaria. – American Journal of Botany 105(5): 1–13
Dillenberger, M.S., N. Wei, J.A. Tennessen, T.-L. Ashman, and A. Liston
(See online at https://doi.org/10.1002/ajb2.1085)
