|Relationship between reproductive polymorphism in the Spotted Salamander and their algal symbiont|
|Chloe M. Dorin, Gabriela Neufeld, Michael M. Gangloff, Lynn Siefferman. Appalachian State University, Boone, NC, United States
The spotted salamander, Ambystoma maculatum, exhibits a unique reproductive polymorphism wherein some females lay clear egg masses while others lay opaque masses. A. maculatum engages in a symbiosis with a single-celled algae, Oophilia amblystomatis, that lives intracellularly within the egg envelopes of A. maculatum and provides embryos with supplemental oxygen via photosynthesis. Clear and opaque egg masses often co-occur in breeding ponds, but proportions of egg mass types vary spatially. Our previous work shows that predators preferentially consume clear egg masses so it is perplexing that they persist. Clear jelly may be an adaptation to low dissolved oxygen environments, possibly by allowing for higher light transmittance and thus increased photosynthesis by O. amblystomatis. Here, we investigate the relationship between jelly polymorphism and dissolved oxygen through both observational and experimental designs. We sampled A. maculatum breeding sites for egg mass proportions, predators, and water physiochemicals. Additionally, we raised clear and opaque egg masses under two different light treatments and then sampled embryonic respiration at two developmental stages.