Senses and signals: evolution of floral signals, pollinator sensory systems and the structure of plant–pollinator interactions

Communication of any sort is complex and communication between plants and animals is particularly so. Plant–pollinator mutualisms are amongst the most celebrated partnerships that have received a great deal of attention for many centuries. At the outset, most pollination studies focused on phenotypic matches and invoked co-evolution to explain plant–pollinator interactions, which gave rise to the concept of pollination syndromes. A few centuries later, there has been a substantial shift in the way we view these mutualistic interactions. In a significant departure from a co-evolutionary framework, numerous studies subsequently showed that there is usually only a loose, non-exclusive matching between flowers and their pollinators. Concurrently, the global prevalence of generalized pollination systems was demonstrated repeatedly. However, our understanding of the evolutionary processes that underlie these mutualisms is still limited. Here, we provide a concise review of the state of our knowledge on the evolution of floral traits and pollinator sensory perception and how these together shape the structure and organization of pollination networks.