Adaptive introgression and cold tolerance in British Rhododendron ponticum – a genomic approach

Supervisors: Richard Milne, Frank Wright, Catherine Kidner, Prof Jianquan Liu

Project Description:

Rhododendron ponticum is invasively naturalised over much of the British Isles, which is much colder than its native range.  Naturalised material contains introgressed germplasm from the highly cold-tolerant R. catawbiense, and such markers are more frequent in colder regions of the UK, suggesting but not proving that introgression from R. catawbiense confers increased cold tolerance.  

This project would make use of the recently completed full genome sequence of R. ponticum, generated by Dr Milne’s collaborators in China, who can be involved in the project.  This will be used as a basis for designing a set of RNA baits to capture sequence data from hybrid populations and herbarium samples.  The bait set will comprise candidate cold tolerant genes as well as single copy genes well dispersed over the genome to allow for FST scanning to detect frequency of introgressed regions from R. catawbiense, and to determine if cold-tolerance associated gene are over-represented in the introgressed set.

Hybridization with R. catawbiense happened in cultivation before naturalisation, followed by numerous plantings all over the country, >120 years ago, allowing for up to 10 generations since.  Thereafter, each naturalised population of R. ponticum provides a replicate test of subsequent selection effects.  Moreover, certain naturalised populations are spread over a range of altitudes (here termed “slope populations”), allowing for differential selection on cold-tolerance genes within such populations.

The student will collect material of R. ponticum from naturalised populations, especially from the top and bottoms of slope populations.  Samples of Rhododendron ponticum from its native sites and herbarium collections from early in its history in the UK will be used for comparison, and samples of R. catawbiense  will be used to confirm genotype of introgressed material. Genome regions and bait loci showing evidence of positive selection will be studied, using the full R. ponticum genome sequence and the literature, to identify the key cold tolerance loci.
This project combines fieldwork and evolutionary biology with NGS and bioinformatics.  The student will also forge connections with China and professional rhododendron breeders.


Milne RI, Abbott RJ (2000).  Origin and evolution of invasive naturalized material of Rhododendron ponticum L. in the British Isles.  Molecular Ecology,  5: 541-556.

Hart ML, Forrest LL, Nicholls JA, Kidner CA (2016) Retrieval of hundreds of nuclear loci from herbarium specimens Taxon, 65 1081-1092

Nicholls JA, Pennington RT, Erik EJM, Hughes CE, Hearn J, Bunnefeld L, Dexter KG, Stone GN,  Kidner CA (2015). Using targeted enrichment of nuclear genes to increase phylogenetic resolution in the the neotropical rain forest genus Inga (Leguminosae: Mimosoideae) Frontiers in Plant Biology 6:710. doi: 10.3389/fpls.2015.00710

If you wish to apply for this project, please go to this link.