DOI: 10.5061/dryad.k6djh9w90
title: Explaining dimorphism polymorphism: Stronger interspecific sexual differences may be favored when females search for mates in the presence of congeners

description: 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.
description: 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.
description: # Explaining dimorphism polymorphism: Stronger interspecific sexual
 differences may be favored when females search for mates in the presence
 of congeners
 [https://doi.org/10.5061/dryad.k6djh9w90](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.