(editor’s note: this video was added by the editor. Decide for yourself whether it illustrates the experimental approach described below)
It’s no secret that grabbing a lizard by its tail will often times leave you with the tail rather than the lizard. Why? Because the tail would simply break off. The voluntarily shedding of the tail in lizards (tail autotomy) has fascinated herpetologists ever since the 70s, and it didn’t take long for those people to notice that the propensity for tail autotomy varies extensively among species, conspecific individuals, or even within the same individual at different developmental stages. Four decades have passed, what might be responsible for the variation in tail autotomy is still not entirely clear. In a recent paper, we tried to solve a piece of the puzzle by testing the hypothesis that lizards might autotomize the tail with different propensities to compensate for their intrinsic risk-taking tendency.
Our idea was simple: bolder lizards, due to their behavioral tendency, tend to expose themselves more to higher predation risk. Therefore, selection might favor higher propensities for tail autotomy in bolder lizards as a compensation mechanism. We were also interested in knowing how food availability in the environment might affect tail autotomy. So, we caught a bunch of juvenile brown anoles from the same population in New Orleans and assigned them into two dietary groups: low versus high food availability. After the lizards reached adulthood, we picked out the males and examined the relationship between boldness and the propensity for tail autotomy. (In case you wonder how we measured the propensity for tail autotomy, we refer you to a paper by Stanley Fox, who contributed greatly to our knowledge of tail autotomy.)
And here’s what we found:
Bolder lizards did autotomize their tails more readily as a means to compensate for their risk-prone personality, but only in the group raised with abundant food. Our results helped explain why lizards from the same population autotomized the tail with different propensity. Moreover, our study highlighted the role of food availability in the cost-benefit dynamics of tail autotomy, which has never been explicitly discussed or tested before. Aside from those exciting implications for the study of tail autotomy, our results also have important bearings on broader topics such as the evolution of trait compensation and animal personality. If you are interested in knowing more about this project, check out our recent paper:
CHI-YUN KUO, DUNCAN J. IRSCHICK and SIMON P. LAILVAUX. (2014). Trait compensation between boldness and the propensity for tail autotomy under different food availabilities in similarly aged brown anole lizards. Functional Ecology DOI: 10.1111/1365-2435.12324