Sexual arms race gave male beetles sticky feet

Science, June 2014

Male diving beetles need fancy footwork to catch a mate. Females in the aquatic beetle family Dytiscidae thrash around to dislodge pursuing suitors, requiring males to use adhesive hairlike structures on their feet to mount them. Scientists believe this chaotic copulation sparked an evolutionary arms race where some male diving beetles evolved circular suckers on their feet in place of the grooved spatula-shaped structures more commonly found on other beetles.