Convergent and divergent evolution in carnivorous pitcher plant traps

Abstract

Contents Summary1035I.Introduction1035II.Evolution of the pitcher1036III.Convergent evolution1036IV.Divergent evolution1038V.Adaptive radiation and speciation1040VI.Conclusions and perspectives1040Acknowledgements1040References1040 Summary The pitcher trap is a striking example of convergent evolution across unrelated carnivorous plant lineages. Convergent traits that have evolved across pitcher plant lineages are essential for trap function, suggesting that key selective pressures are in action. Recent studies have also revealed patterns of divergent evolution in functional pitcher morphology within genera. Adaptations to differences in local prey assemblages may drive such divergence and, ultimately, speciation. Here, we review recent research on convergent and divergent evolution in pitcher plant traps, with a focus on the genus Nepenthes, which we propose as a new model for research into adaptive radiation and speciation.

A phylogenomic analysis ofNepenthes(Nepenthaceae)

“…Furthermore, in recent years a range of studies have demonstrated various ecological adaptations related to nutrient acquisition and sometimes strongly linked to this morphological variation, such as the pitchers of Nepenthes rajah, adapted to catch the faeces of tree-shrews (Bauer et al, 2008; Ulrike Bauer et al, 2012b;Bazile et al, 2015;Clarke et al, 2009;Gaume et al, 2017;Lim et al, 2014;Merbach et al, 2002;Moran et al, 2012;Pavlovič et al, 2011;Scharmann et al, 2013;Scholz et al, 2010). These, along with variations of substrate and altitude, mark them the genus as a good putative example of an adaptive radiation (Bauer et al, 2012a;Clarke and Moran, 2016;Gaume et al, 2016;Thorogood et al, 2018). Many interesting questions remain about the evolution of key adaptations and their correlation with rates of diversification, the role of ecological divergence in speciation, and the importance of introgression and gene flow in the origin of new species or the maintenance of a wider pool of genetic diversity for variation (Thorogood et al, (Bunawan et al, 2017;Golos, 2012;Merckx et al, 2015;Renner and Specht, 2011;Schwallier et al, 2016) but major inconsistencies remain.…”

Guided droplet transport on synthetic slippery surfaces inspired by a pitcher plant

“…Droplet transport on the Nepenthes peristome -Pitfall trap production in carnivorous plants is costly, so strong selection pressures should act on traps to maximise their prey intake [7,33]. Therefore, the ornate, non-planar features on the pitcher peristome are presumably functional and associated with a strong selective advantage.…”

“…Recently, the wettable surface of the carnivorous pitcher plant Nepenthes (Figure 1) has inspired new types of lubricant-infused, slippery surfaces [5,6]. Pitcher plants produce specialised leafderived 'pitfall' traps to attract, capture, retain, kill and digest animal prey to enable them to survive in nutrient-poor environments [7,8]. A key trapping feature is the peristome, which has sloping, macroscopic ridges (Figure 1a), in turn made up of microscopic ridges ( Figure 1b) [9].…”

“…Examining functional natural surfaces in vivo may also offer insights into the evolution of natural systems [19]. Whilst the aquaplaning 3 trapping mechanism of the carnivorous Nepenthes pitcher is well documented [7,20,21], the functionality of the grooves on the peristome surface remains relatively unexplored. Here, we show that capillary action pins droplets to topographical features (grooves), enabling motion along the direction of the feature whilst inhibiting motion across the feature.…”

Population genomics perspectives on convergent adaptation

“…Convergence may also occur on the level of a specific phenotype. Carnivorous pitcher plants have striking convergence for trap morphology (Thorogood et al, 2018). When convergent phenotypes arise in highly-diverged species, it has often been presumed that these changes are due to divergent genetic mechanisms (see Stern, 2013, for review).…”