Reticulate evolution and hybridization in willows (Salix L.)
Final Report Abstract
We studied the phylogeny and evolution notoriously difficult and species-rich genus Salix. We successfully reconstructed the first well-resolved phylogenetic framework for Eurasian shrub willows for c. 80 species by using RAD sequencing markers. This marker clearly confirmed most taxonomic species as monophyletic, but revealed unexpected relationships among species. We could confirm that both ancient and more recent hybridization events in the phylogeny have resulted in the origin of various allopolyploid species with different parental contributions. Morphological characters appear to be adaptive and highly homoplasious. Among the diploid species, a hitherto unknown radiation was detected in the Hengduan mountains and adjacent areas and spatio-temporal evolution in this area was reconstructed. In the European Alps, secondary contact hybridization happens in situ on the recently ice-freed glacier forefield between diploid species, resulting in a new hybrid combination. These early generation hybrids do have some fertility, enabling them to produce further generations. Segregation patterns suggest a predominance of backcrossing to parental species, potentially resulting in introgression of adaptive traits. We conclude that allopolyploidy, secondary contact hybridization and adaptive radiations have shaped the evolutionary history and diversification of the genus Salix.
Publications
- 2016. Evolution in situ: Hybrid origin and establishment of willows (Salix L.) on alpine glacier forefields. Heredity 116, 531–541
Gramlich S, Sagmeister P, Dullinger S, Hadacek F, Hörandl E
(See online at https://doi.org/10.1038/hdy.2016.14) - 2016. Fitness of natural willow hybrids in a pioneer mosaic hybrid zone. Ecology and Evolution 6: 7645-7655
Gramlich S, Hörandl E
(See online at https://doi.org/10.1002/ece3.2470) - 2018. Mit kleinen Schnipseln zum großen Stammbaum - Die Verwandtschaft der europäischen Strauchweiden. Biologie in unserer Zeit, 5(48): 324-331
Wagner, N.D.
(See online at https://doi.org/10.1002/biuz.201810656) - 2018. RAD sequencing resolved phylogenetic relationships in European shrub willows (Salix L. subg. Chamaetia and subg. Vetrix) and revealed multiple evolution of dwarf shrubs. Ecology & Evolution 8: 8243-8255
Wagner, N.D., Gramlich, S., Hörandl, E.
(See online at https://doi.org/10.1002/ece3.4360) - 2018. RAD-seq reveals genetic structure of the F2-generation of natural willow hybrids (Salix L.) and a great potential for interspecific introgression. BMC Plant Biology 18: 317
Gramlich, S., Wagner, N.D, Hörandl, E.
(See online at https://doi.org/10.1186/s12870-018-1552-6)
