Abstract Detail

Phylogenomics

Ning, Weixuan [1], Meudt, Heidi [2], Nicolas, Antoine [3], Plunkett, Gregory [4], Lee, William [5], Tate, Jennifer [6].

Resolving the reticulate evolutionary history of the New Zealand polyploid-rich genus Azorella (Apiaceae).

Genera with species of multiple ploidal levels provide important models for investigating the role of polyploidization in plant diversification. Such groups often have reticulate evolutionary histories partially due to few reproductive barriers between radiated species. Here, we studied 17 polyploid species in Azorella sections Schizeilema and Stilbocarpa that have divergent leaf morphologies, distinct distributional ranges, and varying ploidal levels (4x, 6x, and 10x). All are endemic to New Zealand (NZ), except A. fragosea which is native to Australia (Au). To resolve the species relationships, we sequenced Angiosperms353 bait-set captured single copy nuclear genes (SCNGs) of 125 individuals in 21 Azorella species collected from 72 sites. We also constructed the phylogeny using whole plastomes and nrDNA that were extracted from genome skimming reads from 104 individuals representing 19 Azorella species. Our goal was to determine the origins of the higher polyploids using concordance factors among SCNG trees and genomic SNP variation from bait-set sequenced reads. Although the backbone of the SCNG phylogeny remains unresolved due to the high level of polymorphisms among target genes, our result showed three major clades in Azorella section Schizeilema species (NZ1, NZ2 and Au) that were more closely related to South American relatives than to section Stilbocarpa. NZ1 contained species with three ploidal levels, which included the allodecaploid lineage A. colensoi and its putative parental species, tetraploid A. allanii and hexaploid A. hookeri, identified by network analysis and the genomic introgression test. By contrast, the NZ2 clade only comprised NZ South Island tetraploids, whose origin may be due to hybridization and introgression between species from NZ1 and Au. Finally, the topologies of the resulting plastome and nrDNA trees were not congruent with each other, nor with the SCNGs-based phylogenies. This incongruence provides further evidence to support the network relationships of New Zealand Azorella species.

1 - Massey University, School of Natural Sciences, Massey University, Private Bag 11222, Palmerston North, Palmerston North, 4442, New Zealand
2 - Museum Of New Zealand Te Papa Tongarewa, Botany, PO Box 467, Cable St, Wellington, 6140, New Zealand
3 - Manhattan College, Biology, Leo Building - Room 317D, 4513 Manhattan College Parkway, Riverdale, NY, 10471, United States
4 - New York Botanical Garden, Cullman Program For Molecular Systematics, 384 Collins Ave, Mount Vernon, NY, 10552, United States
5 - Manaaki Whenua - Landcare Research Dunedin, Ecosystems and Conservation, Dunedin 9054, New Zealand, Dunedin, 9054, New Zealand
6 - Massey University, School of Natural Sciences, Massey University, Private Bag 11222, Palmerston North, Palmerston North, 4442, New Zealand

Keywords:
Azorella
Apiaceae
hybridization
Hyb-Seq
whole-genome duplication
phylogenomics
Reticulation
genome skimming.

Presentation Type: Oral Paper
Number: PHYLO III013
Abstract ID:198
Candidate for Awards:None