Is digit ratio in painted male dragon lizards associated with other behaviors?

A recent article in Animal Behaviour (click to link to the paper here) examines the relationship of digit ratio to other specific male behaviors. Embryonic hormone (androgen and estrogen) exposure can be an important determinant of future phenotypic traits and behaviors. In the painted dragon lizard (Ctenophorus pictus) Mats Olsson had found previously that there is a correlation between digit ratio and bib color. In this case, bib means a yellow or orange throat patch. Previously it was established that males with a higher 3D:4D ratio have a higher incidence of bib presence.

There have been a myriad of studies of digit ratio across species, but evidence linking this trait and other behaviors is scant and inconsistent. Beyond the relationship between 3D:4D ratio and bib color, males with and without a bib have differences in reproductive strategies. This indicates that endurance and antipredator behavior may have a relationship to digit ratio as well. Finally, taken together the authors suggest that bib color, 3D:4D ratio and other behavioral traits may have the same proximate mechanisms.

For this study, they examined 3D:4D ratio, bib color, anti-predator behavior (in this case escape response) and endurance. While they found that individuals having a higher 3D:4D ratio had shorter escape response times they did not differ in endurance performance. This negative result points to a different causal mechanism for the digit ratio and bib color from the antipredator behavior and endurance.

I would like to see this study taken a step further by experimentally applying different hormone concentrations to the embryo to see what can be altered by hormones alone.

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