Explaining dimorphism polymorphism: Stronger interspecific sexual differences may be favored when females search for mates in the presence of congeners

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-sh..., 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., , # 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 ...