Cephalopods dazzle prey, woo mates and seamlessly blend into the background using skin that changes in both color and texture (Hanlon and Messenger, 1998). These diverse behaviors in cephalopods and countless others found throughout animals inspire the question of how new behaviors evolve to produce the riotous variety we see today (Tinbergen, 1963). Do novel behaviors stem from newly evolved mechanisms? Or do new behaviors primarily arise through evolutionary “tinkering”, which may co-opt, retool and recombine existing mechanisms and modules? Answering these questions is fundamental to understanding how behaviors evolve. If new mechanisms drive new behaviors, then the behaviors can be more finely tuned and optimized for their current function. Alternatively, if deeply conserved mechanisms are used in new behaviors, those behaviors may be constrained by the evolutionary history of their underpinnings. Unfortunately, relatively few studies successfully disentangle the evolutionary origins of novel behaviors and their underlying mechanisms. For my dissertation, I investigate the evolutionary history of mechanisms underlying a novel behavior of cephalopod chromatophores: the eye-independent expansion of the chromatophores in response to light (hereafter the cephalopod Light Activated Chromatophore Expansion or LACE).
My overarching dissertation research question is whether deeply conserved mechanisms underlie novel behaviors, specifically Octopus bimaculoides LACE. My preliminary data suggest that two deeply conserved modules contribute to the novel octopus LACE (see Fig. 1), resulting in two hypotheses that drive my dissertation research:
Hypothesis 1: A spatially dispersed light sense is an ancestral trait shared among mollusks. This ancestral light sense contributed to the evolution of the novel cephalopod Light Activated Chromatophore Expansion (LACE) behavior.
Hypothesis 2: A deeply conserved genetic mechanism for light detection, present in most animals, is used in mollusk dispersed light sense. These genes formed the molecular basis for phototransduction underlying the novel LACE.