Abstract Detail

Phylogenomics

Moore, Abigail [1], Schenk, John [2].

Resolving Relationships in Mentzelia Section Bartonia (Loasaceae) in the Face of Cytonuclear Discordance.

Previous phylogenetic studies of Mentzelia section Bartonia (Loasaceae) based on two nuclear ribosomal markers created the first phylogenetic framework in which to understand the evolution of the section, but limited molecular variation resulted in several large polytomies that have impeded a complete understanding of species relationships. We applied a genome skimming approach to determine whether additional genetic variation from high-throughput sequencing could robustly resolve relationships in one of the largest polytomies in the section. We constructed libraries and sequenced 20 species, which included three outgroup and 17 ingroup species. For the entire chloroplast genome, read data were assembled using a de novo approach, while reference guided approaches were taken for the nuclear ribosomal cistron region, three anonymous nuclear loci, and a fragment of the mitochondria. Exhaustive measures were taken to ensure phylogenetic and assembly-based errors were not responsible for the observed discordance among gene trees. Significant discordance was identified among the nuclear, chloroplast, and mitochondrial genomes when analyzed individually. The chloroplast genome produced a mostly resolved phylogeny, with the exception of a polytomy that consisted of M. mexicana, M. procera, and M. rusbyi. We infer that the aforementioned clade is likely the result of recent chloroplast capture associated with hybridization. Relationships within the chloroplast phylogeny were not strongly supported overall and it shared only a single common node with the nuclear ribosomal phylogeny. We discuss the evolution of incongruence that might have led to such discordance, including recent and ancient hybridization, incomplete lineage sorting, a high noise to signal ratio, low rates of molecular evolution, and the recent origin of some clades.

Related Links:
Schenk lab website

1 - Ohio University, Environmental and Plant Biology, 22 Richland Ave, Athens, OH, 45701, United States
2 - Ohio University, Department Of Environmental And Plant Biology, 22 Richland Ave., 401 Porter Hall, Athens, OH, 45701, United States

Keywords:
plastid genome
cytonuclear discordance
Genome skimming
genomics
hybridization
incongruence
Loasaceae
Mentzelia
phylogenomics
species tree.

Presentation Type: Oral Paper
Session: PHYLOII, Phylogenomics II
Location: Virtual/Virtual
Date: Tuesday, July 20th, 2021
Time: 4:30 PM(EDT)
Number: PHYLOII007
Abstract ID:440
Candidate for Awards:None