The tangled roots of the ant family tree
A new study in Molecular Biology and Evolution investigates the persistent conflict in ant phylogeny, revealing that complex evolutionary signals and tree reconstruction artifacts are to blame. Researchers analyzed BUSCO genes and found that individual gene trees support three competing hypotheses for the placement of the cryptic Martialinae subfamily. After concatenation, the relative strength of these signals depended on the evolutionary model used. The CAT-PMSF model, which best explained the data’s compositional heterogeneity, positioned Martialinae as the sister to all ants except Leptanillinae. The analysis uncovered strong gene- and site-discordance, with evidence that signals supporting all three hypotheses exist within ant genomes, likely due to incomplete lineage sorting and introgression during early ant evolution.
Study Significance: This research underscores the profound challenges in resolving deep phylogenetic splits, a core task in evolutionary biology, when ancient evolutionary processes like incomplete lineage sorting have left conflicting genomic signatures. For professionals focused on molecular evolution and phylogenetics, it highlights the critical importance of model selection and the inherent limitations of concatenated datasets when dealing with complex evolutionary histories. The findings suggest that for some lineages, a single, unambiguous tree of life may be an unattainable ideal, pushing the field toward more nuanced representations of evolutionary relationships that account for pervasive gene tree discordance.
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