Oogenesis in Cubozoa species: is the morphology of the female gonads different between internal and external fertilization?

Abstract

Reproductive patterns within Medusozoa (Cnidaria) are diverse. This subphylum, comprised by four classes (Hydrozoa, Scyphozoa, Staurozoa and Cubozoa), has a metagenetic life cycle, with sexual reproduction predominantly performed by the medusa stage. However, many aspects of sexual reproduction across this clade remain poorly understood. In my PhD project, I have been studying egg size variation within Medusozoa and its correlation with life-history characters (reproductive strategies, fertilization modes) and environmental conditions (temperature and depth) in order to elucidate evolutionary patterns of sexual reproduction across this group. One focus of this work has been to document oogenesis, the formation of female gonads, in Cubozoa, including new description of oogenesis in one species from Brazil.This internship will expand this documentation of reproduction characteristics within class Cubozoa, which contains roughly 50 described species. This internship proposal aims to test if morphological patterns of female gonads can be inferred by fertilization mode (external or internal), in addition to studying the oogenesis and egg size variation of species within female specimens available in the extensive collection of the National Museum of Natural History (NMNH), Smithsonian Institution (Washington D.C., United States). During this internship, I would analyze female gonads from different families and fertilization modes, comparing patterns of gonad morphology and egg size variation across Cubozoa. By accessing the rich cubozoan collection of the NMNH, which is probably the largest in the world, this internship will mitigate the scarcity of sexual data available for this class by creating and analyzing histological preparations. This project will also continue and expand upon Brazil-US collaborations with Dr. Allen Collins, a long-lasting collaborator of the lab and expert in comparative and evolutionary studies in cnidarians. (AU)