Evolution of Signals and Sensory Systems

Abstract

Sensory systems allow organisms to detect relevant signals in the environment. Signals and sensory systems also connect organisms to each other, forming the foundation for all communication in both interspecific and intraspecific interactions. In this thesis, I explore the interplay between signals and senses through an evolutionary lens. In chapter 1, I survey sensory receptors across all major groups of animals to uncover emerging evolutionary patterns. Building on this characterization of receptors throughout animal evolution, I then investigate species that exemplify how conserved and lineage-specific sensory receptors shape novel organismal adaptations. In chapter 2, I show that infrared radiation is an ancient pollination signal used by cycads to attract their beetle pollinators. I then elucidate the molecular basis of both the signal and the sense: heat production by the plants and infrared detection by the beetles. In chapter 3, I trace the evolutionary trajectory of the cephalopod-chemotactile receptors (CRs), from their ancestral role as neurotransmitter receptors to sensory receptors expressed in octopus and squid arms. Finally, in chapter 4, I study pheromone-producing organs across a butterfly radiation to reveal a tradeoff in the evolution of male signals: getting too attractive is costly. These studies span levels of biological organization from molecular mechanisms to the complexity and wonder of behaviors, revealing fundamental insights into the coding logic of animals’ sensory worlds.