Locating evolutionary precursors on a phylogenetic tree

Brigitte Marazzi, Cécile Ané, Marcelo F. Simon, Alfonso Delgado-Salinas, Melissa Luckow, Michael J. Sanderson

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


Conspicuous innovations in the history of life are often preceded by more cryptic genetic and developmental precursors. In many cases, these appear to be associated with recurring origins of very similar traits in close relatives (parallelisms) or striking convergences separated by deep time (deep homologies). Although the phylogenetic distribution of gain and loss of traits hints strongly at the existence of such precursors, no models of trait evolution currently permit inference about their location on a tree. Here we develop a new stochastic model, which explicitly captures the dependency implied by a precursor and permits estimation of precursor locations. We apply it to the evolution of extrafloral nectaries (EFNs), an ecologically significant trait mediating a widespread mutualism between plants and ants. In legumes, a species-rich clade with morphologically diverse EFNs, the precursor model fits the data on EFN occurrences significantly better than conventional models. The model generates explicit hypotheses about the phylogenetic location of hypothetical precursors, which may help guide future studies of molecular genetic pathways underlying nectary position, development, and function.

Original languageEnglish (US)
Pages (from-to)3918-3930
Number of pages13
Issue number12
StatePublished - Dec 2012


  • Deep homology
  • Extra-floral nectary
  • Homoplasy
  • Trait evolution

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • General Agricultural and Biological Sciences


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