Evolutionary experience and the phylogenetic relationships of plants have both been proposed to influence herbivore-plant interactions and plant invasion success. However, the direction and magnitude of these effects, and how such patterns are altered with increasing temperature, are rarely studied. Through laboratory functional response (FR) experiments, we tested whether the per capita feeding efficiency of an invasive generalist herbivore, the golden apple snail, Pomacea canaliculata, is dependent on the biogeographic origin and phylogenetic relatedness of host plants, and how increasing temperature alters these dependencies. The feeding efficiency of the herbivore was highest on plant species with which it had no shared evolutionary history, i.e. novel plants. Further, amongst evolutionarily familiar plants, snail feeding efficiency was higher on those species more closely related to the novel plants. However, these biogeographic dependencies became less pronounced with increasing temperature, whereas the phylogenetic dependence was unaffected. Collectively, our findings indicate that the susceptibility of plants to this invasive herbivore is mediated by both biogeographic origin and phylogenetic relatedness. We hypothesize that warming erodes the influence of evolutionary exposure, thereby altering herbivore-plant interactions and perhaps the invasion success of plants.
phylogenetic functional response
In the functional response (FR) experiment, five plant species that share an evolutionary history with P. canaliculata were chosen: Alternanthera philoxeroides (alligator weed), Eichhornia crassipes (water hyacinth), Ipomoea batatas (sweet potato), Myriophyllum aquaticum (parrot feather) and Pistia stratiotes (water lettuce). In addition, we chose five plant species with which P. canaliculata has had no evolutionary exposure: Apium graveolens (Chinese celery), Colocasia esculenta (taro), Ipomoea aquatica (water spinach), Hydrocotyle vulgaris (pennywort) and Lactuca sativa (lettuce).We collected all host plant species on the day of the experiment to ensure their freshness. Each of these species is common in wetlands and agricultural areas of South China and the snail was observed to consume all these plants to some degree in the laboratory.Then we measured the plant consumption by apple snail along 7 plant biomass gradients at 5 temperature gradients.
data for phylogenetic functional response.csv
The phylogeny of 10 species used in this study
To verify the phylogenetic structure of these species, for each of the 10 species we searched GenBank for matK gene sequences, which are commonly used in published plant phylogenies (Cadotte 2013). We included a gymnosperm Platycladus orientalis as the out-group species. Sequences were aligned with ClustalW (Thompson et al. 2002). The Bayesian phylogeny was reconstructed using BEAST version v1.8.2 (Drummond et al. 2012). The Bayesian MCMC chain was run for one million generations, and convergence was checked using Tracer version v1.6.0 (http://beast.bio.ed.ac.uk/Tracer). The maximum clade credibility tree was used to quantify phylogenetic pattern by TreeAnnotator version v1.8.2 (Drummond et al. 2012)
phylogeny for species used in this study