Phylogenetic relationships among carnivorous plants of the angiosperm order Caryophyllales have been explored, although a robust phylogeny encompassing all carnivorous genera is absent. We sample nuclear ribosomal spacer (internal transcribed spacer) and chloroplast intergenic spacer (PY-IGS), along with previously sequenced DNA from members of the noncore Caryophyllales, for use in Bayesian statistics and maximum likelihood-based searches of phylogeny. Taxonomic relationships across genera are refined, and three strongly supported clades are identified: monophyletic Droseraceae, Nepenthaceae, and a third clade containing Ancistrocladaceae, Dioncophyllaceae, and Drosophyllaceae. In combination with phylogenetic reconstruction, stochastic character mapping is used to assess evolutionary changes in the morphology of glands that are found on the lamina and involved in the digestion of prey. The presence of sessile glands is identified as the likely ancestral character state, and stalked and pitted glands are suggested to have been acquired independently by ingroup and outgroup taxa. Additionally, in some genera we found a lack of association between gland vasculature and plant carnivory, demonstrating that the internal architecture of glands is not indicative of whether the plant is a functional carnivore. Finally, we discuss how adaptive changes resulting in the evolution of the carnivorous gland may have occurred either by emargination of the leaf blade or homologous transformation of pinnae.
All Science Journal Classification (ASJC) codes
- Ecology, Evolution, Behavior and Systematics
- Plant Science