Increased resolution in the face of conflict: phylogenomics of the Neotropical bellflowers (Campanulaceae: Lobelioideae), a rapid plant radiation

Laura P. Lagomarsino, Lauren Frankel, Simon Uribe-Convers, Alexandre Antonelli, Nathan Muchhala

Research output: Contribution to journalArticlepeer-review

Abstract

Background and Aims
The centropogonid clade (Lobelioideae: Campanulaceae) is an Andean-centred rapid radiation characterized by repeated convergent evolution of morphological traits, including fruit type and pollination syndromes. While previous studies have resolved relationships of lineages with fleshy fruits into subclades, relationships among capsular species remain unresolved. This lack of resolution has impeded reclassification of non-monophyletic genera, whose current taxonomy relies heavily on traits that have undergone convergent evolution.
Methods
Targeted sequence capture using a probe-set recently developed for the centropogonid clade was used to obtain phylogenomic data from DNA extracted from both silica-dried and herbarium leaf tissue. These data were used to infer relationships among species using concatenated and partitioned species tree methods, and to quantify gene tree discordance.
Key Results
While silica-dried leaf tissue resulted in longer assembled sequence data, the inclusion of herbarium samples improved taxonomic representation. Relationships among baccate lineages are similar to those inferred in previous studies, although they differ for lineages within and among capsular clades. We improve the phylogenetic resolution of  Siphocampylus , which forms ten groups of closely related species which we informally name. Two subclades of  Siphocampylus  and two individual species are rogue taxa whose placement differs widely across analyses. Gene tree discordance (including cytonuclear discordance) is rampant.
Conclusions
This first phylogenomic study of the centropogonid clade considerably improves our understanding of relationships in this rapid radiation. Differences across analyses and the possibility of additional lineage discoveries still hamper a solid and stable reclassification. Rapid morphological innovation corresponds with a high degree of phylogenomic complexity, including cytonuclear discordance, nuclear gene tree conflict and well-supported differences between analyses based on different nuclear loci. Together, these results point to a potential role of hemiplasy underlying repeated convergent evolution. This hallmark of rapid radiations is probably present in many other species-rich Andean plant radiations.
Original languageAmerican English
JournalAnnals of Botany
Volume129
DOIs
StatePublished - May 2022

Keywords

  • Burmeistera
  • Campanulaceae
  • Centropogon
  • Lobelioideae
  • Neotropics
  • Siphocampylus
  • convergent evolution
  • cytonuclear discordance
  • gene tree conflict
  • museomics
  • phylogenomics
  • rapid radiation
  • taxonomy

Disciplines

  • Biology

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