A Sticky Situation: Assessing Adaptations for Plant Carnivory in the Caryophyllales by Means of Stochastic Character Mapping

Abstract

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Inside the trap: gland morphologies, digestive enzymes, and the evolution of plant carnivory in the Caryophyllales

“…A variety of sessile, stalked, or pitted glands associated with the carnivorous leaves allow for prey capture as well as excretion of enzymes and absorption of digested material, however, vasculature within these glands is not required for plant carnivory [16••]. Families sister to the carnivorous Caryophyllales exhibit similar gland morphologies, yet it is likely that stalked and pitted glands evolved independently in these lineages, separate from the evolution of stalked and pitted glands in the carnivores [16••]. In addition to sticky glands, waxes and superhydrophylic trichomes are located on carnivorous trap surfaces.…”

“…Most recent phylogenetic analyses have recovered families Droseraceae, Nepenthaceae, and a clade comprised of Ancistrocladaceae, Dioncophyllaceae, and Drosophyllaceae as monophyletic [16••]. …”

“…While the presence of vasculature is not a strong indicator of functional carnivory as many carnivorous glands are not vascularized (e.g. glands types of Dionaea , Aldrovanda , and Nepenthes ) (Figure 1) [16••], the multicellular glands thus far characterized in the non-carnivorous outgroups do not appear to have associated vasculature (Figure 1). Ancestral state reconstruction suggests that sessile glands without vasculature are likely the ancestral state for the carnivorous Caryophyllales, while stalked and pitted glands were acquired secondarily and independently by the non-carnivorous sister families and by various lineages of carnivores [16••].…”

“…Multicellular glands involved in plant carnivory are either sessile, stalked, or pitted, and may contain either xylem or phloem. Phylogenetic relationships depicted among major carnivorous plant genera of the Caryophyllales are based upon maximum likelihood and Bayesian inference analyses and character states refer to stochastic character mapping of gland states [16••]. Gray in the phylogeny represents non-carnivorous taxa, while black represent carnivorous taxa.…”

“…Illustrations located below character states depict examples of gland types for members of the carnivorous Caryophyllales and outgroup Plumbaginaceae (not to scale). For more detail in regard to gland morphologies, see [16••,17–19,21,64]. …”