J Syst Evol

• Research Articles •    

What is truth: Consensus and discordance in next‐generation phylogenetic analyses of Daucus

David M. Spooner*, Holly Ruess, Shelby Ellison, Douglas Senalik, and Philipp Simon   

  1. USDA, Agricultural Research Service, Department of Horticulture, University of Wisconsin, Madison, Wisconsin 53706‐1590, USA
  • Received:2019-12-04 Accepted:2020-08-20 Online:2020-08-25

Abstract:

High‐throughput (next‐generation) DNA sequencing has removed barriers to data quantity and quality, and it has produced phylogenies with high statistical support. Such data are useful to address phylogenetic congruence among individual genes. Concatenated analyses of unlinked genes often produce well‐resolved phylogenetic trees with bootstrap support on major nodes at or approaching 100%, but they have been criticized for providing incorrect phylogenies for various reasons to include a history of hybridization, introgression, and incomplete lineage sorting. The present study compares next‐generation sequencing results of the same accessions of Daucus with different genomic regions, of which three have been reported before: (i) the entire plastid genome, (ii) 47 mitochondrial genes, and (iii) 94 conserved nuclear orthologs. Here, we report a fourth dataset, (iv) 564 895 nuclear SNPs. There are areas of discordance in all four results using the same accessions analyzed with maximum parsimony, maximum likelihood, and with the nuclear data species trees through a coalescent analysis. The nuclear results show significant areas of discordance that were unexpected, because these studies used the same DNA samples, the nuclear studies were generated from large and high‐quality datasets with the SNPs distributed on all nine linkage groups of Daucus carota, and the results were supported by high bootstrap values. These results raise questions concerning the best data and analytical methods to reconstruct and understand the “truth” of a phylogeny.

Key words: carrot, phylogenetic discordance, phylogenomics, resequencing, SNPs