Dewlap size
We measured dewlap area and perimeter from digital photos in ImageJ.
Dewlap area and perimeter were measured by creating line segments
throughout the border of the dewlap, ultimately forming a polygon and
obtaining the area and perimeter of it. We measured the dewlap for each
lizard twice to verify the repeatability of this method, which was 1.0.
We used a digital x-ray system to capture skeletal images from
euthanized lizards. Using ObjectJ, a plug-in for ImageJ, we estimated of
body size by measuring snout-vent length (SVL), the distance from the
tip of the snout (i.e., the edge of the soft tissue) to the final
vertebrae that had forward-facing arms. SVL values were then
log-transformed and regressed against log-transformed dewlap area and
perimeter. The resulting residual values represent body size-adjusted
dewlap size.