Meeting Abstract

S3-1.5  Saturday, Jan. 5  Brave New Propagules: Terrestrial Embryos of Aquatic Fish MARTIN, K.L.*; MORAVEK, C.L.; CARTER, A.L.; Pepperdine Univ.; Pepperdine Univ. ; Charleston Southern Univ. kmartin@pepperdine.edu

Species within many lineages of teleost fishes reproduce terrestrially, despite lacking the key evolutionary innovation of the amniotic egg. In contrast with shelled eggs of reptiles and birds, the anamniotic eggs that contains an embryo of a fish or amphibian is typically much smaller and enclosed in relatively simple membranes. Anamniotic embryo incubation duration is usually brief and hatchlings arrive as larvae rather than juveniles. Advantages of terrestrial incubation include the increased availability of warmer temperatures and higher oxygen levels that may speed development, while disadvantages include desiccation, exposure to novel predators and pathogens, and the risk of hatching into a hostile habitat. In most species of teleosts that nest terrestrially or semi-terrestrially, adults are fully aquatic, and resultant hatchlings often require the return to an aquatic habitat. However, some amphibious teleost fishes not only incubate eggs in air but also emerge out of water as adults and may be active terrestrially. Providing the appropriate incubation conditions and maternal investment for a fish embryo in a terrestrial environment is challenging, and most teleost examples occur in the marine intertidal zone, with its predictable ebbing and flooding of seawater. Examples of terrestrially breeding freshwater teleosts and their habitats will be provided for contrast and comparison with examples of terrestrial incubation among amphibian taxa. The selection pressures leading to successful nesting and early development out of water for fish and amphibians may provide numerous alternate routes to vertebrate land invasion, even if only for the early portion of the life cycle.