Evolutionary innovations underlie the rise of diversity and complexity—the two long-term trends in the history of life. How does natural selection redesign multiple interacting parts to achieve a new emergent function? We investigated the evolution of a biomechanical innovation, the latch-spring mechanism of trap-jaw ants, to address two outstanding evolutionary problems: how form and function change in a system during the evolution of new complex traits, and whether such innovations and the diversity they beget are repeatable in time and space. Using a new phylogenetic reconstruction of 470 species, and X-ray microtomography and high-speed videography of representative taxa, we found the trap-jaw mechanism evolved independently 7–10 times in a single ant genus (Strumigenys), resulting in the repeated evolution of diverse forms on different continents. The trap mechanism facilitates a 6–7 order of magnitude greater mandible acceleration relative to simpler ancestors, currently the fastest recorded acceleration of a resettable animal movement. We found that most morphological diversification occurred after evolution of latch-spring mechanisms, which evolved via minor realignments of mouthpart structures.  This finding, whereby incremental changes in form lead to a change of function, followed by large morphological reorganization around the new function, provides a model for understanding the evolution of complex biomechanical traits, as well as insights into why such innovations often happen repeatedly.

See published paper for methodological details on the different data included in this archive.

ReadMe file for Booher et al., "Functional innovation promotes diversification of form in the evolution of an ultrafast trap-jaw mechanism in ants" PLoS Biology, Data Archive

===Included one zip archive “Supplemental Data and Code Archive”

1) Phylogenetic analyses and trees

 /ExaML/examl-fulldata  Files for running the ExaML analysis on the full dataset (885 specimens), and resulting files and logs

/ExaML/examl-reducedspecies  Files for running the ExaML analysis on the reduced dataset of high-data species (132 specimens), and resulting files and logs

/BEAST2_divdating_root1  Files for running the BEAST2 divergence dating on the fixed ML topology with root1 position and resulting logs and mcc tree

/BEAST2_divdating_root2  Files for running the BEAST2 divergence dating on the fixed ML topology with root2 position and resulting logs and mcc tree

/TreeFiles collection of trees resulting from the different analyses, as presented in the figures (Fig 2 + Fig S4, S5, S6). Node annotations are bootstraps and booster support values.  

2) Ancestral State Estimation

/Ancestral State Analyses_root1  folder including R code for the ancestral state reconstruction and associated data/functions assuming a “root1” node position. Also included is the xml and log files for reconstructing ancestral states using a relaxed clock in BEAST.

/Ancestral State Analyses_root2  folder including R code for the ancestral state reconstruction and associated data/functions assuming a “root2” node position. Also included is the xml and log files for reconstructing ancestral states using a relaxed clock in BEAST.

3) Morphometrics

Landmark data and R code to load them and perform a PCA

4) Datasets 1-4

Dataset 1: Specimens used to reconstruct the phylogeny.  Further collection information can be accessed by searching the specimen code on Antweb.org. 

Dataset 2: X-Ray micro-CT images used in this study, with scanning parameters.  

Dataset 3:  Detailed measurment data from the mandible closure experiments, used to make Figure 4A.

Dataset 4:  Compilation of kinetic data used in Figure 4C.

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CT Scan images in dicom format are included as individual Zip archives.