Fig. 2

Morphological traits related to male competitive ability (male’s ability to reach and persist in aggregations). Neither male body size nor eye asymmetry influenced the male’s ability to reach an aggregation (a-b). Males that persisted more days in the aggregations were smaller, but did not show different eye asymmetry (c-d). Median values are represented by the lines inside the boxes, which span the first and third quartiles, and points represent data outside 1.5 times the interquartile range above the upper quartile and bellow the lower quartile. Data from different colonies and aggregations were merged (see colony and aggregation effects in Additional file 4: Figure S3)