Paedomorphosis

On February 26th, our herpetology class went out the Mee-Man Park in Shelby Forest and completed a transect experiment. Our TA had gone out the day before and placed plastic species on the ground and in the trees, on and off the trail. There were two separate transects set up, one in a terrestrial environment and the other was aquatic; 26 species were placed on each trail (originally 29 on the terrestrial but 2 were lost for unknown reasons). We ran out of time so I only got to complete the terrestrial transect where I only found 20 of the specimens hidden. I thought this experiment was quite fun!

After our experiment was complete, my group had to hang around for a few minutes for the other group to return form the pond where the aquatic transect was set up. During this period, a male that works for the park I assume, brought over a specimen in a Tupperware container and said “this is a paedomorph, does anyone know what it is?” I guessed spotted salamander larvae because of the spots on the lower body, however, I was told no. Dr. Parris reminded me (in other words) that paedomorphosis refers to a developmental process in which a trait fails to develop to the point observed in the ancestral species. The species we were shown turned out to be a Mole Salamander (Ambystoma talpoideum). Morphs with larval traits can reproduce, hence their morphological development is truncated relative to their reproductive development and thus they exhibit paedogenesis. Below is a picture of the larvae and it really captures the difference between the larval stage and the adult form.

Mole Salamander Larvae


Mole Salamander Adult (photo taken on Feb 11th trip)



Serena Babin
Memphis, TN