A Review of "A brighter future for frogs? The influence of carotenoids on the health, developement and reproductive success of the red-eye tree frog.

          In the Animal Conservation Journal  article, A brighter future for frogs? The influence of carotenoids on the health, development and reproductive success of the red-eye tree frog, the authors Ogilvy, Preziosi, and Fidgett comment on the lack of research in respect to diet of frogs in captivity. They cite many sources that comment on the increasing risk of extinction among amphibians worldwide and note the importance of observing the diet of these species in captivity so as to provide protection and maintain diversity among threatened species worldwide (Stuart et al., 2004). In this particular study, Ogilvy et al. focused on the species Agalychnis callidryas, or the red-eye tree frog. Specifically they wanted to know the effects of carotenoids in the diet of the red-eye tree frogs in captivity, especially as they pertained to skin color and reproductive success.
          Overall there were four parts to this study. In part one, Ogilvy et al., sought to determine if the amount of carotenoids in the diet affected the growth rate in tadpoles. the examined a total of fifty- four tadpoles and three treatment groups. The first treatment group was a control diet consisting of no carotenoids , the second treatment group diet consisted of low carotenoids and the third treatment group diet consisted of high carotenoids. They determined that there was no significant difference in the growth or developmental rate of the tadpoles.
           The second part of this study focused on the post-metamorphic stage of the tadpoles in part one. The metamorphs from part one were split into two groups that included a similar number from each tadpole diet treatment. One group remained a control while the other group continued to be fed a high carotenoid post-metamorphic diet. It was determined that there was a significant difference in females reaction to a high carotenoid post-metamorphic  diet and male reaction to a high carotenoid post-metamorphic diet. Females on a high carotenoid post-metamorhic diet grew faster than control females and male controls did not differ in growth rate significantly from males fed a high carotenoid post-metamorphic diet.
            In part three of this study, Ogilvy et al. measured the fecundity of the females fed a high carotenoid post-metamorphic diet versus the control females fed a no carotenoid diet. They discovered four out of five females fed the high carotenoid diet produced fertile spawn, while none of the control females produced fertile spawn. This part of the study in particular has important implications for the diet of red-eye tree frogs in captivity. This shows that while it may not be obvious right away the implications of a high carotenoid diet in captivity, it has a great impact on the production of future generations of red-eye tree frogs.
            Finally, in part four of the study, at seventeen months post-metamorphosis frogs being fed the control were switched to a high-carotenoid diet while frogs being fed the high carotenoid diet were switched to a no carotenoid diet. It was discovered that despite these dietary changes post-metamorphosis no change in phenotype was discovered. However, previous to these seventeen months post-metamorphosis significant changes in phenotype were seen between those fed the high carotenoid diet and the control. Those fed the high carotenoid diet had redder toe-pads and brighter green coloring. These results suggest that there is a certain point post- metamorphosis (0-17 months) in which carotenoids are essential to the red-eye tree frog's diet.
       In conclusion, it was shown in this study by Ogilvy et. al that a high carotenoid diet is essential to red-eye tree frogs in captivity, especially females. It is most critical that the females receive a high carotenoid diet in the 0-17 months post- metamorphosis as it affects their coloration and their ability to mate and produce fertile offspring. These findings are particularly important in the world of conservation biology and herpetology as more and more amphibian species are threatened or endangered. It proves that more research needs to be done on a broader range of amphibians and other reptiles to ensure that we are able to preserve as many species as possible before they become endangered or extinct. This article was particularly fascinating to me as the red-eye tree frog is my favorite amphibian. I feel as if many people are familiar with the red-eye tree frog as it is a common subject for the cover of biology textbooks or nature posters. It would be a shame to lose such and adorable frog and more seriously such diversity, especially when it can be prevented so easily, with just minor adjustments to the females post-metamorphic diet.
                             
                                                               Work Cited
      Ogilvy, V., Preziosi, R.F., Fidgett, A.L. (2012). A brighter future for frogs? The influence of carotenoids on the health, development  and reproductive success of the red-eye tree frog. Animal Conservation. 15, 480-488.