One of the most challenging things an organism will do throughout its lifetime is balance its energy budget. Energy is used to grow, develop, reproduce, survive, and how animals allocate that energy will forever be a fascinating question to biologists. If you have more energy, then in theory you should be able to be more active and be a “fitter” individual. For most lizards, excess energy can be represented by fat stores, so if individuals tend to store more energy, then they should be less able to put energy into other reproductive or physiological traits. This was the idea tested by Marzieh Rouzbehani of Trinity University, working in the lab of Michele Johnson.
They studied two anole species: crested and bark anoles (Anolis cristatellus and A. distichus) and found that the two species exhibit different energy-physiology relationships. They found crested anoles with larger eggs had more fat stores, and that crested anoles with larger eggs did not exhibit activity tradeoffs. Bark anoles on the other hand exhibited no relationship between egg mass and fat stores, but found a trend where bark anoles with larger egg masses had lower activity levels. In addition for both species, they found no relationship between hematocrit (the volume percentage of red blood cells in blood) and activity levels, and their work emphasizes the complexity that is species-specific physiological dynamics for female anoles. Different anole species are likely to have different physiological traits influence their behavior and activity in different ways. Fascinating stuff!