The evolution of toxin-resistant Na+,K+-ATPases in fireflies.Flora Borne (Columbia University)

Toxic cardiotonic steroids (CTSs) act as a chemical defense in many fireflies (Lampyridae) by inhibiting the essential enzyme Na⁺,K⁺-ATPase. While most firefly species synthesize these toxins internally, some acquire them through predation onother fireflies. Using evolutionary analyses of Na⁺,K⁺-ATPase sequences and gene editing in<i>Drosophila</i>, we investigated how two ecologically distinct species have evolved CTS resistance via different genetic pathways. Our work provides insight into theevolutionary mechanisms that allow essential proteins to adapt under the constraints imposed by their critical functions and highlights the potential role of epistasis in shaping protein evolution.