Pederson's cleaner shrimp, Ancylomenes pedersoni, on its corkscrew sea anemone host in the Southern Caribbean. Photographed in Curaçao by Benjamin M. Titus. By applying topology testing and extensive demographic modeling to a shrimp species complex in the Gulf of Mexico, Titus and collaborators revealed a novel diversification pathway in the Greater Caribbean region, involving secondary contact, historical introgression, and endemic hybrid speciation.