The Phenology of the Symbiotic Association between Ambystoma maculatum and Unicellular Algae (Oophila) Using Molecular Techniques

The symbiosis between developing Spotted Salamanders (Ambystoma maculatum) and the unicellular alga known as Oophila amblystomatis appears to be mutualistic, with involved parties trading apparent benefits within the salamander egg capsule, but the spatiotemporal ecology of the interaction has yet to be thoroughly explored. Using newly developed primers for quantitative polymerase chain reaction (PCR), we sampled 149 salamander egg masses of various ages from six breeding ponds in northeast Alabama. We documented the presence of algal DNA within egg capsules throughout the developmental process. Regression via linear mixed model estimation showed a positive relationship between the age of egg masses and the probability of algal DNA detection and a negative trend when comparing egg-mass age and qPCR cycle quantification value. These trends indicate an increase in both the probability that a given egg will contain algal DNA and the amount of algal DNA an egg contains, if present, as age increases. We found no effects of pond, site within pond, or year of sampling in either case.