Relation between sexual allometry and function in the sawfly Leseha vespa (Hymenoptera Tenthredinidae)

Abstract

A recent theoretical model predicts that the allometries of structures under sexual selection vary according to their functions in sexual interactions. Structures that are specialized for exclusive use as courtship devices, and not as weapons or threat devices, were predicted to tend to show low allometric values. Detailed observations of behavior and morphological design in Leseha vespa indicated that the sexually dimorphic abdominal tergite VIII of males functions to court females, but does not function as a weapon or in threats directed toward other males. As predicted by the theory, the allometric slope of tergite VIII length was lower than those of other body traits that were not modified for sexual interactions.

KEY WORDS:

• static allometry
• sexual selection and allometry
• “pure” courtship function
• abdominal tergite

ACKNOWLEDGEMENTS

I am very grateful to David Smith for identifying the wasps and for kindly providing specimens of Aneugmenus flavipes, Klaus Mehltreter for identifying the fern, Kenji Nishida for commenting on the manuscript, accelerating his contribution to the Smith & Nishida paper and other favors, Paul Hanson for putting me in touch with all of the above, and Francesco Dessì-Fulgheri for help beyond the call of duty with figures. I also thank Paula Calderon for help with the SEM, and the Smithsonian Tropical Research Institute for continued support.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author.

Additional information

Funding

This study did not receive any specific from funding agencies in the public, commercial, or not-for-profit sectors.