Jerry Coyne writes about a paper that demonstrates a strange adaptation of certain Bornean pitcher plants: “Good to the last dropping: pitcher plant evolves to be shrew loo”
Working on Mount Kinabalu in Borneo, Lee et al. discovered that three species of pitcher plants in the genus Nepenthes (N. lowii, N. macrophylla, and the N. rajah, the worlds largest carnivorous plant, shown in Fig. 2), have evolved features that make them attractive to treeshrews of the genus Tupaia. (Treeshrews are neither rodents nor shrews; theyre a group more closely related to primates than to rodents). The plants have recurved lids that produce a sweet substance that the tree shews lap up while sitting astride the pitchers. The authors found that, depending on the species of plant, between 60% and 90% of the pitchers contained fecal pellets from treeshrews. Video cameras placed near pitchers of N. rajah captured 7 treeshrew visits, lasting an average of 24 seconds, and one of these showed the beast crapping into the pitcher. Previous analysis (Clarke et al. 2009) showed that these pellets provide a large fraction (58-90%) of the nitrogen needed by N lowii.
I find it fascinating that there have been enough tree shrews to make this scheme work for the pitcher plants. I suppose urine, which is less visible, would also supply nitrogen just as effectively.