If you followed the barrage of blogposts we wrote from SICB 2014, you might recall some discussion of the information actually conveyed by anole displays and dewlaps (1, 2). The upshot of these studies is that anole displays are complex. We see unexpected relationships between various traits and the probability of success in male-male competition, and different traits correlate with different measures of male success. A recent study by Steffen and Guyer (2014) adds to our growing knowledge of the information conveyed by different dimensions of multimodal anole displays. When viewed together with previous research, this study presents us with an even messier picture than before of how Anolis lizards communicate with each other.
Steffen and Guyer (2014) set up paired competitions between size-matched male Anolis sagrei in a lab setting, implementing two treatments–males either compete for access to a single perch, or for mating access to a single female. All interactions were recorded, and display behaviours–headbobs, push-ups, dewlap extensions–were quantified. Further, the spectral reflectance of both the centre and the margin of the dewlap (which can be strikingly different in A. sagrei) was also measured. The question asked by the paper was straighforward: which display and dewlap traits are related to an individual lizard’s status as a winner or loser of competitions?
In both competitive contexts, only two traits seem to be important–a composite axis of behavioural variation, and one of three composite axes describing the colour of the margin of the dewlap. Lizards who headbob, push-up, and extend their dewlaps more during competitive interactions are more likely to win than lizards who display less. Curiously, lizards with lower UV reflectance of the dewlap margin are more likely to win than lizards with brightly UV-reflecting dewlap margins.
Of the two variables, display behaviour was more highly correlated with the probability of success than dewlap margin UV-reflectiveness. I’m curious about how the two variables are themselves related–do lizards that display more also have less bright dewlap margins? The authors propose that a dewlap’s reflectance might relate to its conspicuousness, and it would be interesting to know if different individuals are conspicuous in different ways.
Each of the studies conducted so far on how anoles convey information to each other has examined different dewlap and display variables, studied different competitive contexts, and used different measures of male quality. It therefore isn’t surprising that we seem far from reaching a consensus on what the dewlap says.
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Kenneth E. Barnett
Awesome stuff Ambika!
Any conjecture, on a minor tangent, as to why A. carolinensis, A. sagrei, and even A. equestris (not to mention Iguana iguana), will often head bob and or dewlap display to humans? I just had this happen with an A. carolinensis male on a stalk. It saw me, bobbed 3 or 4 times, and then let me see what he was worth pink dewlap style. How does this work? Is he hoping another anole SEES him do this to ME? 🙂
Best,
Kenny
Ambika Kamath
The usual explanation for such behaviour is “pursuit deterrence,” which means that lizards display at creatures they think might be predators to indicate that they’ve spotted the predator and will be able to escape, so it isn’t worth the predators time/effort to chase after them.
John Doe
Anoles showing their dewlap doesn’t always mean they are threatened by your presence or any of the other things you said, I’ve been around these guys for years and many of them are quite tame where I live, I can bring them food and give them water straight from a plastic cup
And they will come running to it to drink, of stick their heads in there to get a drink too. I’ve had years of experience with these lizards that gather around my house and they like it when you talk to them in a soft spoken voice and in return the male anoles with display their dewlaps and you and do pushups as well and so will the female anoles, in fact one that was battling cancer/ infection due to exposure of insecticide let me stroke underneath her tail and in return she looked at me and showed her bright red dewlap at me, she knew I was there to help and support her as she was dying of cancer/infection , her body was riddled with so much infection you could see it through her skin, it was making her face disfigured and her eyelids were so swollen she lost vision in both eyes as a result, also in the days that followed she lost her ability to eat and drink as well and after a week she stopped showing up all together and that’s when I knew she was gone, still though I made it my mission to show up and let her know that she mattered and didn’t have to suffer alone. Anoles are fascinating creatures and if you get the chance to befriend one, do because you’ll have a lifelong friend for life that enjoys not only your companionship but also becomes an out door pet that you can feed, give water too
And sometimes if they trust you enough you’ll get to pet their tails like I did with mine when I was interacting with them on my property
Thomas Sanger
Ambika, for those of us not was well versed in this literature, what do you mean by “different measures of male quality”? Just how many different measures have been used and is there any logical relationship between them (whether quantified or not)? Are these different measures driven by field versus laboratory studies where different amounts of control are possible? I found myself thinking about this seemingly minor comment for several hours this afternoon so I thought I would just ask.
Ambika Kamath
Gosh, sorry to cause you so much puzzlement, Thom! All of these measures of “male quality” seem to function as proxies for reproductive success: the probability of winning a competition (this study, and Jordan Bush’s poster at SICB ’14), territory size (Jordan Bush’s poster), performance variables such as sprint speed or jumping ability or bite force, and immunocompetence (Tess Driessen’s talk, SICB ’14). The differences among studies seem partially explained by what variables are examined in the first place. The lab/field difference is explored nicely by Jordan’s work, which questions whether these different measures of quality are actually related in ways we expect. Links to descriptions of both these other studies are in the post.
Thanks for asking me to clarify the phrasing–I shouldn’t have taken it for granted!
Thomas Sanger
Thanks. I wasn’t sure if that comment was meant to go beyond those studies into the bottomless pit of anole literature. Either way, it seems like a critical step towards consensus is to standardize the proxies on male quality. Its fun to think about and probably difficult to operationalize.
Ambika Kamath
Yeah, I think the key step will be understanding how each of those measures actually relate to reproductive success, ideally in a variety of different contexts.
Simon Lailvaux
There are a lot of problems with the way that male “quality” is conceptualized and measured generally, and this is one of my current pet peeves. Ambika, I think you are right in that this is exactly what needs to be done. For those who are interested (and at the risk of some blatant self-promotion), a review that discusses these and related issues can be found here
Ambika Kamath
Thanks for sharing the review–looking forward to reading it!