How does evolution break functional barriers to fine-tune adaptation?

University of St Andrews

How do organisms adapt to their environment when faced with conflicting pressures, particularly when those pressures act in direct opposition? The mechanisms by which adaptive evolution engineers resolutions to such functional constraints remains an open question in biology. One topical theory is that traits within the same organism may vary independently of each other, a phenomenon called modularity, resulting in finely tuned adaptations which bypass functional constraints imposed by countervailing pressures. Alternatively, could what we observe be the product of an evolutionary tug-of-war, leading to sub-optimal compromises in functionality? I will test this using tropical katydids. Male katydids use modified sound-producing structures on their forewings to communicate with females, but many species have also evolved elaborate forewings which resemble dead or living leaves, enabling them to hide in plain sight from predators. How did these exaggerated leaf mimicking forewings evolve whilst simultaneously under such strong pressure for continued sound production? I will collect bioacoustics data and measure wing shape and structure in specimens from a diverse community in western Colombia and test how this dual functionality of signalling and camouflage is maintained, and the degree to which evolution repeats itself when faced with the same functional constraints. Leaf-like wings have evolved several times independently across katydids and the high species diversity found within this group of insects make them a unique system for understanding how sensory trade-offs can be resolved and the evolutionary avenues via which these resolutions can be reached. My findings will reveal how nature resolves trade-offs in design, a problem that all engineers and manufacturers need to solve.