Quantifying the repeated evolution of insect raptorial forelegs.

Area of Science:

• Evolutionary biology
• Comparative morphology
• Insect anatomy

Background:

• Raptorial forelegs in insects evolved independently across lineages for prey capture.
• Common function can lead to morphological similarity, but evolutionary pathways are poorly understood.

Purpose of the Study:

• To quantify and compare the morphological evolution of raptorial forelegs and other body parts across six insect lineages.
• To investigate patterns of evolutionary similarity, including shifts in mean shape, reduced variation, and direction of evolution.

Main Methods:

• Comparative analyses of segmental dimensions to quantify shape in morphospace.
• Examination of three aspects of morphological similarity: shift in mean shape, reduction in shape variation, and similarity in evolutionary direction.

Main Results:

• Insect raptorial forelegs and forebody shapes showed low-to-moderate similarity in evolutionary direction, but not other characteristics.
• Evolutionary patterns differed between terrestrial and aquatic habitats.
• Correlated evolution between foreleg and forebody shape suggests functional relationships.

Conclusions:

• Insect raptorial foreleg evolution is not parallel or convergent; it exhibits morphological diversity, indicating a many-to-one mapping of shape to function.
• Functional relationships between foreleg and forebody are supported by correlated evolutionary patterns.
• Habitat influences the direction of morphological evolution in raptorial forelegs.