The Anolis dewlap is a recurrent topic of discussion on Anole Annals. This is not surprising considering that it is commonly viewed as playing a role in many aspects of social interaction, including species recognition and even sexual selection, although, I am unaware of empirical studies supporting sexual selection in the context of female choice.
A recent post by Ian Wang asked the question, “Does This Dewlap Go With My Signalling Environment?” In order to answer this question I would encourage the readers of Anole Annals to have a discussion of what really is an “anole’s signaling environment.”
The paper by Ng et al. (2012) presents some interesting results, and I would encourage everyone to read this paper. The amount of data presented in this paper is impressive, with the authors combining molecular, dewlap reflectance, and satellite data (i.e., GIS data) to evaluate if there is a relationship between dewlap traits and climatic variables across populations of A. distichus. As the precision of GIS data increases, the ability to explore questions at a finer geographical scale is becoming more common. This paper nicely illustrates this approach. Additionally, A. distichus is a nice system for the study of dewlap variation. In fact, in my opinion, one of Al Schwartz’s (1968) best anole monographs describes all sorts of geographic variation in the distichus complex. This monograph is a must read for all Anole Annals fans, with beautiful plates and a lot of natural history data.
One of the main findings of Ng et al. is that geographic variation in dewlap coloration is correlated with the “habitat types” in which populations are found. Interestingly, habitat type seems to have a stronger signal than geographic or genetic distance between populations. I have to admit that I am biased, but this is music to my ears. However, before we jump into further conclusions, I feel that it is important to take a step back and evaluate the question I posed at the start of this post – namely, what is the “signaling environment”?