Explaining dimorphism polymorphism: Stronger interspecific sexual differences may be favored when females search for mates in the presence of congeners
Data files
May 17, 2024 version files 504.82 KB
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Centroid_Measurement.xlsx
15.65 KB
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Final_Wing_Landmarks.xlsx
45.46 KB
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ForeFemur_Length_Raw.xlsx
13.75 KB
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LandmarkAverage.xlsx
145.51 KB
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LandmarkCheck.xlsx
200.13 KB
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RawLandmarkData.xlsx
81.49 KB
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README.md
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Abstract
Why are some species sexually dimorphic while other closely related species are not? While all females in genus Strauzia share a multiply-banded wing pattern typical of many other true fruit flies, males of four species have noticeably elongated wings with banding patterns “coalesced” into a continuous dark streak across much of the wing. We take an integrative phylogenetic approach to explore the evolution of this dimorphism and develop general hypotheses underlying the evolution of wing dimorphism in flies. We find that the origin of coalesced and other darkened male wing patterns correlate with the inferred origin of host plant sharing in Strauzia. While wing shape among non-host-sharing species tended to be conserved across the phylogeny, shapes of male wings for Strauzia species sharing the same host plant were more different from one another than expected under Brownian models of evolution and overall rates of wing shape change differed between non-host-sharing species and host-sharing species. A survey of North American Tephritidae finds just three other genera with specialist species that share host plants. Host-sharing species in these genera also have wing patterns unusual for each genus. Only genus Eutreta is like Strauzia in having the unusual wing patterns only in males, and of genera that have multiple species sharing hosts, only in Eutreta and Strauzia do males hold territories while females search for mates. We hypothesize that in species that share host plants, those where females actively search for males in the presence of congeners may be more likely to evolve sexually dimorphic wing patterns.
https://doi.org/10.5061/dryad.k6djh9w90
The dataset includes images of all Strauzia wings that were mounted, landmarked, and analyzed. Each wing image was landmarked using ImageJ and the raw landmark coordinates are included in an Excel Spreadsheet. Wing landmark coordinates were compared across all Strauzia species to determine if host plant sharing and mate searching behaviors impact wing shape and pattern variation. We find that wing shape and pattern differs among male Strauzia that share the same host plants, but not in males that do not share hosts with other Strauzia species. This pattern may also be true in other host plant sharing Tephritidae.
Description of the data and file structure
Each file is an image of a Strauzia wing saved in the .tif format. We photographed all Strauzia wings using a Leica IC80 HD camera linked to a Leica M125 microscope (Leica Microsystems, Wetzlar, Germany) set to 2X magnification. These wing images were processed in ImageJ as described in the manuscript and landmarks were placed in 8 locations on each image. The images are named with the specimen ID number which corresponds to the sample ID numbers in Supplemental Table 1. In some cases, the image ID will also include the species ID, sex (M/F), the magnification level (2), and the right or left wing (R/L). Species IDs may include ARC = S. arculata, LTUDE = S. longitudinalis, VITT = S. vittigera, LONG = S. longipennis, NOCT = S. noctipennis, RUG = S. rugosum, VERB = S. verbesinae, UVE = S. uvedaliae, STRUM = “strumosus fly”, INT = S. intermedia, PERF = S. perfecta, BUSH = “Bush’s fly”, or UNK = unknown species.
This dataset also includes the raw landmark coordinates obtained for each image included in the analysis. RawLandmarkData includes the specimen ID and each image was landmarked twice, so there is a 1 or 2 to designate which set of landmarks are listed. The remaining columns X1, Y1 through X8, Y8 are the X and Y coordinates for each of the 8 landmarks. LandmarkCheck shows the error checking protocol for each landmarked individual. LandmarkAverage shows the averaging of the two sets of landmarks for each individual. The X in the Final Wing column indicates that the following coordinates are the final, averaged set that are used for analysis. Final_Wing_Landmarks shows the final wing landmarks for each specimen and includes a column identifying the species for each individual. ForeFemur_Length_Raw shows the raw fore femur measurements for each species and individual listed. Centroid_Measurement lists the image ID, the measured centroid size, and the species identification.
Wing pictures were taken using a Leica IC80 HD camera linked to a Leica M125 microscope (Leica Microsystems, Wetzlar, Germany) set to 2X magnification. Wing landmarks were placed in ImageJ and landmark analyses were completed using geomorph v4.0.1 and PAST v4.04.