Meeting Abstract
Throughout their evolutionary history, organisms have evolved a myriad of novel complex traits to increase their survival and reproductive success. However, the mechanism underlying the origin and diversification of novel traits is still roughly unresolved. Here, we introduce morphological and genetic studies on the origin of the upper lips of Cypridinid ostracods, which the ostracods use for bioluminescence and luminous courtship signals. The light reaction involves a substrate, luciferin, and a luminesce enzyme, luciferase, each of which is synthesized in separate gland cells in the upper lip and discharged in a mucus-like substance. Previous histology suggests specialized cell types exist in the upper lips of luminous ostracods for separately secreting enzymes, substrates, and mucus, but non-luminous lineages have fewer cell types which makes this taxon a tractable model system to study the evolution of novel traits. The close proximity to the mouth and the flexible movement of the upper lip during feeding suggest the upper lip may secrete digestive enzymes to aid in the ingestion of food. Given the relationship between luciferase and digestive enzymes, we predict that cells involved in the production of luciferase differentiated from digestive glands in the gut. We demonstrate through immunohistostaining and confocal microscopy, the localization of luciferase within the light organ and in vesicles surrounding the gut parenchyma. Our preliminary results suggest that bioluminescent cell types in the upper lip may have diversified from digestive cells in the gut parenchyma. Our study has implications for understanding the emergence of novel functional traits in organisms.
