Received: 24 February 2021 | Revised: 22 April 2021 | Accepted: 12 May 2021 DOI: 10.1111/jeb.13875 RESEARCH PAPER Female reproductive mode shapes allometric scaling of male traits in live- bearing fishes (family Poeciliidae) Andrew I. Furness1 | Andres Hagmayer2 | Bart J. A. Pollux2 1Department of Biological and Marine Sciences, University of Hull, Hull, UK Abstract 2Department of Animal Sciences, Reproductive mode is predicted to influence the form of sexual selection. The viviparity- Wageningen University, Wageningen, The driven conflict hypothesis posits that a shift from lecithotrophic (yolk- nourished) to Netherlands matrotrophic (mother- nourished or placental) viviparity drives a shift from precopula- Correspondence tory towards post- copulatory sexual selection. In lecithotrophic species, we predict Andrew I. Furness, Department of Biological and Marine Sciences, University of Hull, that precopulatory sexual selection will manifest as males exhibiting a broad distribu- Hull, UK. tion of sizes, and small and large males exhibiting contrasting phenotypes (morphology Email:
[email protected] and coloration); conversely, in matrotrophic species, an emphasis on post- copulatory Funding information sexual selection will preclude these patterns. We test these predictions by gathering Netherlands Organization for Scientific Research, Grant/Award Number: data on male size, morphology and coloration for five sympatric Costa Rican poeciliid 864.14.008; Academy Ecology Fund 2017; species that differ in reproductive mode (i.e. lecithotrophy vs. matrotrophy). We find U.S. National Science Foundation, Grant/ Award Number: 1523666 tentative support for these predictions of the viviparity- driven conflict hypothesis, with some interesting caveats and subtleties. In particular, we find that the three lec- ithotrophic species tend to show a broader distribution of male sizes than matrotrophic species.