lants and their herbivores constitute more than half of the organisms on earth. Therefore a better understanding of the evolution of plant defenses against their herbivores may be central for our understanding of biodiversity and species interaction. Over the last half century, complementary theories and hypotheses have been developed to try to explain the extraordinary variation in plant defensive strategies, and, thanks to interdisciplinary interaction between ecologist, behaviorists, physiologist, and chemists, it has given rise to the body of work, collectively known as “plant defense theory”. Nowadays, advances in community phylogenetic and metabolomic analysis are the key components for refining plant defense theories at a novel frontier. Because until recently, only foliage defense was considered and because species evolutionary history was not fully taken in account, I aim to use powerful and detailed analyses to test plant defense theories taking the whole plant approach in a phylogenetic context.
Here I propose to study the evolution of anti-herbivore defense and their possible contribution to coexistence in three genera with species that have colonized the entire altitudinal cline of the Swiss Alps. Over the course of three years, I firstly aim to uncover altitudinal gradients of whole plant defenses and herbivory. Then I expect to answer the questions of what are the suites of defensive traits promoting habitat specialization. I will subsequently test how plant functional traits and herbivores interact to maintain habitat specialization (altitudinal levels) and coexistence between closely related species. Finally, I will focus on how habitat specialization (altitudinal levels) and herbivory shape the connection between aboveground and belowground plant defenses.
One of the keys to the success of such a project is the combination of different approaches. Plant defensive traits will be analyzed through high throughput chromatography, mass spectrometry and various other chemical analytical techniques. I will then include field experiments where plants and herbivores will be factorially manipulated to specifically quantify the relative contribution of biotic (herbivory) and abiotic (e.g. soil nutrients, temperature) to habitat specialization. Also, I will use genomic information to create phylogenetic trees of the studied species, in order to address questions on the macroevolution of defensive traits along the altitudinal cline.
All these results will enhance our knowledge of the ecological and evolutionary processes that occur among different trophic levels, and predict how the future global change might influence not only each species individually, but the various interactions as a whole.