Macroevolution of sexually selected weapons: weapon evolution in chameleons

Area of Science:

• Evolutionary Biology
• Sexual Selection
• Herpetology

Background:

• Large-scale evolutionary patterns of sexually selected traits, particularly male weapons, are understudied.
• Chamaeleonid lizards offer a diverse model system with 11 weapon types across ~220 species.

Purpose of the Study:

• To analyze the evolutionary patterns of 11 weapon types in chameleons using a time-calibrated phylogeny.
• To investigate the frequency of weapon evolution, persistence, and correlation between sexes.

Main Methods:

• Phylogenetic methods were applied to data from 165 chameleon species.
• Analysis focused on the origins, losses, and long-term persistence of weapon traits.

Main Results:

• All 11 weapons evolved multiple times, with origins generally exceeding losses.
• Weapons exhibit long persistence (>30 million years, some >65 million years).
• Hotspots of weapon evolution correlate with larger male body size and show strong male-female correlation.

Conclusions:

• Weapon evolution in chameleons is characterized by frequent recurrence and long persistence.
• Body size and sexual dimorphism influence weapon evolution hotspots.
• These findings establish a baseline for understanding large-scale weapon evolution patterns in clades.