Figure 1.
Schematic of butterfly flight mill used in all experiments.
A lightweight rod was attached to a post via a near-frictionless pivot. A thin wire was glued to the thorax of each monarch and the wire was attached to the rod during flight trials. A 5 cm flag was attached to the other end of the rod, and the flag passed through a photogate (not shown) with each rotation so that the speed and duration of flight could be monitored via computer. A video of this apparatus is provided as supplemental material (Video S1).
Figure 2.
Frequency-distribution of male and female orange hue scores aggregated across experiments 1–3.
See methods for description of color measurement.
Figure 3.
Relationship between orange hue score and distance flown on the flight mill for all male (A) and female (B) monarchs in this study.
Note that the x- and y-axis scales differ for the two sexes.
Figure 4.
Forewings from three monarchs that span the range of hue scores (values above wings) in this study.
Magnified sections show close-up of scales from each individual.