"The effect of stress and stress hormones on dynamic colour-change in a sexually dichromatic Australian frog"

• Christina Kindermann^a, , 
• Edward J. Narayan^a, 
• Francis Wild^b, 
• Clyde H. Wild^a, 
• Jean-Marc Hero^a

Amplexus is a form of psuedocopulation found in mostly amphibians. Its when the male holds on to the females with his front legs and fertilized the female eggs with his sperm.  An Austrailian Tree Frog, Litoria wilcoxii, changes colors during amplexus. They go from brown to a bright yellow. Kindermann et al  2013, conducted a study to compare and illustrate how the color of amplecting males change. They also wanted to investigate to see if a stress hormone had anything to do with the dynamic color change of these animals. Adult males were studied in Numinbah Valley, The different types of stressors they used were, handling, saline injection, toe-clipping, and ACTH hormone injection.  The color change was measured using photography during amplexus.  They used different methods and protocols for the experimental stressors. After the first photograph, 12 frogs where handled and toe clipped, six frogs were injected with ACTH and five were injected with saline. For handing, they measured the frogs from snout to urostyle  in mm and they were weighed. The ACTH and Saline doses for the  each frog was by a 25 gauge needle. The ACTH dose for the frogs was 0.446 mmg ACTH g-1 body mass and the dose for the saline was 100uL of 0.9% saline solution. Photographs were taken within 5-10 min and then 20-30 mins after each experimental stressor.

They found that toe clippings were the only experimental stressor that  had a significant change in color.

I found this article interesting because I only thought that Chameleons where the only herp that changed colors. It's interesting to know that there are frogs that change colors also. I think it's pretty cool that these animals change colors during copulation. 

http://www.sciencedirect.com.nuncio.cofc.edu/science/article/pii/S109564331300069X?np=y