Reproductive and physiological response to environmental stress in Anolis sagrei and Anolis carolinensis

Abstract

Some species appear to be more well-suited than others for invasion success; Anolis sagrei (the brown anole) is one such species. What makes an invasive species like the brown anole apparently so well adapted to colonizing new environments? There have been different methods of invasion studied, but it is believed that brown anoles do not deal with stress the same as native species like Anolis carolinensis (the green anole), whose native territory the brown anole invades. Previous work demonstrated that while green anole males react to a simulated stress response with reduced territory guarding, brown anole males showed no such reduction. In the present study we tested whether female brown anoles would show the same trend with reproductive fitness (measured by egg production) when exposed to a simulated stress. We used the same method of transdermal application of corticosterone to both green anoles and brown anoles as used previously. We dosed a control group of both species with sesame oil and a treatment group of both species with a mixture of sesame oil and corticosterone. We found the brown anoles showed the expected trend where the females had the same high reproductive output whether stressed or not. The green anoles, though the reproductive output was very low, had no significant difference in egg production between the control and the treatment groups. We expected the green anoles to show a decrease in reproduction when exposed to stress, but that was not supported. We propose that because the green anoles may have been stressed beforehand during capture and shipping, and because we received our green anoles near the end of the breading season, the results we obtained for green anoles may be unreliable. Further experimentation needs to be done on female green anoles specifically to determine their reproductive response to stress.