Female reproductive mode shapes allometric scaling of male traits in live‐bearing fishes (family Poeciliidae)

Abstract

Reproductive mode is predicted to influence the form of sexual selection. The viviparity‐driven conflict hypothesis posits that a shift from lecithotrophic (yolk‐nourished) to matrotrophic (mother‐nourished or placental) viviparity drives a shift from precopulatory towards post‐copulatory sexual selection. In lecithotrophic species, we predict that precopulatory sexual selection will manifest as males exhibiting a broad distribution of sizes, and small and large males exhibiting contrasting phenotypes (morphology and coloration); conversely, in matrotrophic species, an emphasis on post‐copulatory sexual selection will preclude these patterns. We test these predictions by gathering data on male size, morphology and coloration for five sympatric Costa Rican poeciliid species that differ in reproductive mode (i.e. lecithotrophy vs. matrotrophy). We find tentative support for these predictions of the viviparity‐driven conflict hypothesis, with some interesting caveats and subtleties. In particular, we find that the three lecithotrophic species tend to show a broader distribution of male sizes than matrotrophic species. Furthermore, large males of such species tend to exhibit proportionately large dorsal and caudal fins and short gonopodia relative to small males, while these patterns are expressed to a lesser extent in the two matrotrophic species. Finally, large males in some of the lecithotrophic species exhibit darker fins relative to small males, a pattern not evident in either matrotrophic species. One unexpected finding was that even in the matrotrophic species Poeciliopsis retropinna and Poeciliopsis paucimaculata, which lack courtship and dichromatic coloration, some morphological traits exhibit significant allometric relationships, suggesting that even in these species precopulatory sexual selection may be present and shaping size‐specific male phenotypes in subtle ways.

Multiple paternity in superfetatious live‐bearing fishes

“…In this study we investigated two species that carried on average two simultaneous, overlapping broods. There is, however, pronounced variation among species in the level of superfetation across the Poeciliidae, with the maximum number of simultaneous broods per female in a given species ranging from 2 up to 14 (Furness, Avise et al, 2021, Furness, Hagmayer et al, 2021; Pires, Banet et al, 2011; Pires, Bassar et al, 2011). To study how higher levels of superfetation might affect multiple paternity and paternity skew, future studies should include species that can carry more simultaneous broods (e.g.…”

“…The males have small bodies, long genitalia (i.e. copulatory organs called gonopodia) and lack bright coloration, conspicuous ornamental display traits and courtship behaviour, a combination of traits that is typically associated with sneak or coercive mating behaviour (Furness, Avise et al, 2021, Furness, Hagmayer et al, 2021; Pollux et al, 2014). Both species exhibit superfetation, carrying on average two broods per female, both in P .…”

Morphological traits for allometric scaling of the European Sea Bass Dicentrarchus labrax (Linnaeus, 1758) from Southern Portugal population

“…These concepts directly contribute to estimating fish biomass from length data (Kapiris & Klaoudatos, 2011; Konan, 2017; Randall, 2002; Rodríguez et al ., 2017; Sangun et al ., 2007), providing a species condition factor (Jisr et al ., 2018; Prestes et al ., 2019), helping to predict fish feed consumption (Wiff & Roa‐Ureta, 2008) and estimate stocking densities under land‐base farm‐like conditions (Merino et al ., 2022). However, allometry also differentiates life‐history and morphologic traits, such as growth patterns during early developmental stages (Comabella et al ., 2013; Lackmann et al ., 2022; Mitra et al ., 2016; Osse & Boogaart, 1995; Stoltz et al ., 2005) and fish behaviour (Baldauf et al ., 2010; Barros et al ., 2015; Dunlap et al ., 2019; Taugbol et al ., 2020), which in turn influence population and community structure and set distinctive spatial, evolutionary and geographical distributions (Davenport, 2003; Furness et al ., 2021; Garita‐Alvarado & Ornelas‐Garcia, 2021; Kapiris & Klaoudatos, 2011; Oliveira et al ., 2018; Summers & Ord, 2022; Vega‐Trejo et al ., 2022). Therefore, allometric relations may improve the current knowledge on commercially important fish species, foreseeing their conservation and/or sustainable exploration of fish stocks, e.g ., by assessing optimal release size in fish‐stocking programs (Lorenzen, 2000).…”