DOI: 10.5061/dryad.kkwh70shf
title: Morphological measurements of the ant stinging apparatus associated with: Evolutionary simplification and functional shifts of the ant stinger

description: Morphological evolution reflects a balance between the emergence of novel
 traits and the reduction or loss of existing traits, and both of these
 processes shape the diversity of life. Trait simplification, which
 involves the reduction or loss of structures, is a common phenomenon that
 provides adaptive advantages in novel ecological contexts. In this study,
 we examined the evolutionary dynamics and morphological outcomes of the
 reduction and simplification of the stinging apparatus in ants to
 elucidate the effect of these changes on broader evolutionary
 trajectories. Using a phylogenetically informed sampling of 98 ant genera,
 we explored how stinger morphology evolved in conjunction with behavioral
 and ecological changes, employing linear morphometrics and phylogenetic
 comparative methods. Our results revealed that transitions from piercing
 to nonpiercing stingers were substantially associated with dietary
 diversification and shifts in foraging strategies, thus reflecting the
 evolutionary compromises between defense, predation, and ecological
 specialization. Piercing stingers promoted predatory efficiency and
 ecological specialization, while nonpiercing stingers imparted behavioral
 and dietary versatility, such as herbivory and cooperative foraging. These
 findings highlight that morphological simplification is a key adaptive
 mechanism in driving ecological transitions and diversification and
 promoting evolutionary innovation.
description: # Morphological measurements of the ant stinging apparatus associated
 with: Evolutionary simplification and functional shifts of the ant stinger
 Dataset DOI:
 [10.5061/dryad.kkwh70shf](https://doi.org/10.5061/dryad.kkwh70shf) ##
 Description of the data and file structure This dataset
 (stinger_measurements.txt) contains measurements of individual muscle
 areas and linear traits of the ant stinging apparatus, recorded from one
 side of each specimen using 3D Slicer. All linear and cross-sectional
 measurements were obtained directly from 3D volume renderings. The dataset
 includes muscle cross-sectional areas, lengths of stinger components, and
 head width (HW) as a proxy for body size. **Variables:** *
 t8domm – Tergo-tergalis orthomedialis of segment VIII; *
 t8dpmm – Tergo-tergalis paramedialis of segment VIII; *
 t8dolm – Tergo-tergalis ortholateralis of segment VIII; *
 t8dcm – Tergo-coxalis (solus); * t8ccim – Coxo-coxalis interior; *
 t9domm – Tergo-tergalis orthomedialis of segment IX; *
 t9dcm1 – Tergo-coxalis anterior externalis; * t9dcm2 – Tergo-coxalis
 anterior internalis; * t9dcm3 – Tergo-coxalis lateralis; *
 t9dcm4 – Tergo-coxalis medialis; * t9cam1 – Coxo-apophysealis major
 anterior; * t9cam2 – Coxo-apophysealis major posterior; *
 t9cam3 – Coxo-apophysealis minor; * t9ccim – Coxo-coxalis interior; *
 gap9 – Stylet length, measured along the venom canal from its origin in
 the valve chamber to the stylet tip, following either a straight or curved
 path depending on the canal’s course. * st_leng – Stinger length, measured
 as a line extending from the articular process of the sting bulb along the
 venom canal, from its origin in the valve chamber to the stylet tip. *
 HW – Head width, used as a proxy for overall body size. **Notes** *
 Measurements are in mm² for muscle cross-sectional areas and mm for linear
 dimensions. * All measurements were taken on the right-hand side of the
 stinging apparatus. * Stinger proportion (not in the table) was calculated
 separately as stylet length (`st_leng`) / stinger base length. * Stinger
 base length (not in the table) was not measured directly but calculated as
 the difference between stinger length (`st_leng`) and stylet length
 (`gap9`). * Muscle group assignments (MG1–MG4) follow anatomical and
 functional divisions (see manuscript).