Evolutionary co-option of trap-jaw ant mandible strikes: defensive interactions with antlions

The co-option of existing traits for novel functions is fundamental to many theories of trait evolution, but relatively few studies have examined evolutionary co-option at a behavioral level. Trap-jaw ants in the genus Odontomachus have a rapid and powerful mandible snap that is used during predation to disable fast or dangerous prey. Previous research suggests that some trap-jaw species may have co-opted the high forces generated by the mandibles for escape: in threatening situations ants direct their strikes against the substrate and launch themselves into the air. Until now, no actual predators or competitors have been found in the field against which trap-jaw use their “escape jumps.” Here, I examine the use of mandible snapping behavior in two trap-jaw species (Odontomachus brunneus and Odontomachus relictus) during their interactions with predatory antlions in the genus Myrmeleon. Using behavioral observations, high-speed videography, and traditional bioassays, I describe how trap-jaw ants can use their mandible strikes to escape from antlion pits. Interestingly, while both species use the mandible snap for predation, only O. brunneus use the mandible snap to escape from antlion pits. A comparison of the kinematic properties of mandible strikes suggests that differences in force generation might contribute to the behavioral differences between these species. Taken together, my results indicate that trap-jaw mandible snaps can be used to escape from natural predators, lending support to the idea that this predatory behavior has been evolutionarily co-opted for anti-predator defense.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Entomology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2012

Author dc:creator

• Larabee, Fredrick

Contributors dc:contributor

• Suarez, Andrew V.

• Trap-jaw Ants
• Evolutionary Co-Option
• Predator-Prey Interactions
• Predator Avoidance

Statement dc:rights

• Copyright 2011 Fredrick Larabee

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/29470

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/29470