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The evolution of two distinct strategies of moth flight

Citation

Aiello, Brett (2021), The evolution of two distinct strategies of moth flight, Dryad, Dataset, https://doi.org/10.5061/dryad.3ffbg79jp

Abstract

Across insects, wing shape and size have undergone dramatic divergence even in closely related sister groups. However, we do not know how morphology changes in tandem with kinematics to support body weight within available power and how the specific force production patterns are linked to differences in behavior. Hawkmoths and wild silkmoths are diverse sister families with divergent wing morphology. Using 3d kinematics and quasi-steady aerodynamic modeling, we compare the aerodynamics and the contributions of wing shape, size, and kinematics in 10 moth species. We find that wing movement also diverges between the clades and underlies two distinct strategies for flight. Hawkmoths use wing kinematics, especially high frequencies, to enhance force, and wing morphologies that reduces power. Silkmoths use wing morphology to enhance force, and slow, high amplitude wingstrokes to reduce power. Both strategies converge on similar aerodynamic power and can support similar body mass ranges. However, inter-clade within-wingstroke force profiles are quite different and linked to the hovering flight of hawkmoths and the bobbing flight of silkmoths. These two moth groups fly more like other, distantly related insects than they do each other, demonstrating the diversity of flapping flight evolution and a rich bio-inspired design space for robotic flappers.

Methods

Live specimens of five different species from each sister-family (10 total species). Species from the hawkmoth (Sphingidae) family include: Eumorpha achemon, Amphion floridensis, Hyles lineata, Paonias myops, and Smerinthus ophthalmica. Species from the silkmoth (Saturniidae) family include: Actias luna, Automeris io, Antheraea polyphemus, Hyalophora euryalus, and Eacles imperialis.

The body and wing morphology was digitized for each live specimen using the StereoMorph package (version 1.6.2) (2) in R (version 3.4.2; The R Foundation for Statistical Computing). The methods are outlined in detail in the manuscript methods.

Each moth was then recorded by three high-speed cameras flying in a wind tunnel. The details of the cameras and calibrations are outlined in the methods of the text.

The data uploaded in this repository include: raw kinematic data, raw morphological data, and the images used to digitize the morphology of each specimen. In addition, we include flight videos of each species, which are all labeled according to the species name. The raw kinematic data contains the Fourier Coefficients for every wingstroke of every individual of every species used in this study. The corresponding equation to evaluate these coefficients is found in the methods section of the manuscript. We also include the cofficients for the species-averages kinematics of every species. Raw .csv files are also included that contain the x, y, and z points of the full wing and body kinematics for every species. The columns are all labeled with the appropriate landmark name which can be correlated with the methods of the main text. The output data from the analysis of all these raw data are all included as supplemental data files in the main text.