Plastome data reveal multiple geographic origins of Quercus Group Ilex
- Published
- Accepted
- Subject Areas
- Biogeography, Ecology, Evolutionary Studies, Plant Science
- Keywords
- Fagaceae, Mediterranean, Plastome polyphyly, Ancient introgression, Incomplete lineage sorting, Decoupled phylogenies
- Copyright
- © 2015 Simeone et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
- Cite this article
- 2015. Plastome data reveal multiple geographic origins of Quercus Group Ilex. PeerJ PrePrints 3:e1615v1 https://doi.org/10.7287/peerj.preprints.1615v1
Abstract
Nucleotide sequences from the plastome are currently the main source for assessing taxonomic and phylogenetic relationships in flowering plants and their historical biogeography at all hierarchical levels. One exception is the large and economically important genus Quercus (oaks). Whereas differentiation patterns of the nuclear genome are in agreement with morphology and the fossil record, diversity patterns in the plastome are at odds with established taxonomic and phylogenetic relationships. However, the extent and evolutionary implications of this incongruence has yet to be fully uncovered. The DNA sequence divergence of four Euro-Mediterranean Group Ilex oak species (Quercus ilex L., Q. coccifera L., Q. aucheri Jaub. & Spach., Q. alnifolia Poech.) was explored at three chloroplast markers (rbcL, trnK-matK, trnH-psbA). Phylogenetic relationships were reconstructed including worldwide members of additional 55 species representing all Quercus subgeneric groups. Family and order sequence data were harvested from gene banks to better frame the observed divergence in larger taxonomic contexts. We found a strong geographic sorting in the focal group and the genus in general that is entirely decoupled from species boundaries. Main plastid haplotypes shared by distinct oak lineages from the same geographic region and high plastid diversity in members of Group Ilex are indicative for a polyphyletic origin of their plastomes. The results suggest that incomplete lineage sorting and repeated phases of unidirectional introgression among ancestral lineages of Group Ilex and two other main Groups of Eurasian oaks (Cyclobalanopsis and Cerris) caused this complex pattern. Comparison with the current phylogenetic synthesis also suggests an initial high- versus mid-latitude biogeographic split within Quercus. High plastome plasticity of Group Ilex reflects geographic area disruptions, possibly linked with high tectonic activity of past and modern distribution ranges, that did not leave imprints in the nuclear genome of modern species and infrageneric lineages.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Plastome divergence in Fagales
Intra- and intertaxonomic minimum and maximum pairwise genetic distances in Fagales based on the used plastid markers
RbcL and trnK-matK haplotype networks
haplotype networks of the investigated dataset based on rbcL and trnK-matK markers