Testing ontogenetic patterns of sexual size dimorphism against expectations of the expensive tissue hypothesis, an intraspecific example using oyster toadfish (Opsanus tau).

Teresa L Iglesias,Gabriela Hogue,Richard Morris,Alex Dornburg,Katerina L Zapfe,April Lamb,Richard Wong,Dan L Warren,Laura Lukas

doi:10.1002/ece3.3835

Abstract

Trade‐offs associated with sexual size dimorphism (SSD) are well documented across the Tree of Life. However, studies of SSD often do not consider potential investment trade‐offs between metabolically expensive structures under sexual selection and other morphological modules. Based on the expectations of the expensive tissue hypothesis, investment in one metabolically expensive structure should come at the direct cost of investment in another. Here, we examine allometric trends in the ontogeny of oyster toadfish (Opsanus tau) to test whether investment in structures known to have been influenced by strong sexual selection conform to these expectations. Despite recovering clear changes in the ontogeny of a sexually selected trait between males and females, we find no evidence for predicted ontogenetic trade‐offs with metabolically expensive organs. Our results are part of a growing body of work demonstrating that increased investment in one structure does not necessarily drive a wholesale loss of mass in one or more organs.

Highlights

Pronounced differences in ecology, life history, or morphology between males and females of the same species are common features of the vertebrate Tree of Life (Barrett & Hough, 2012; Herler, Kerschbaumer, Mitteroecker, Postl, & Sturmbauer, 2010; Karp et al, 2017; Lamb et al, 2017; Nottebohm & Arnold, 1976)
Potential energetic trade-offs between selection for Sexual size dimorphism (SSD) and investment in metabolically expensive organs are rarely considered, precluding a broader understanding of how SSD shapes fundamental aspects of phenotypic evolution in vertebrates
The swim bladders of oyster toadfish and their close relatives (Batrachoididae) are not primarily used for buoyancy, but instead serve as highly derived sound production organs that are unusual among teleost fishes (Fine, 1975)

Summary

Introduction

Pronounced differences in ecology, life history, or morphology between males and females of the same species are common features of the vertebrate Tree of Life (Barrett & Hough, 2012; Herler, Kerschbaumer, Mitteroecker, Postl, & Sturmbauer, 2010; Karp et al, 2017; Lamb et al, 2017; Nottebohm & Arnold, 1976). Potential energetic trade-offs between selection for SSD and investment in metabolically expensive organs are rarely considered, precluding a broader understanding of how SSD shapes fundamental aspects of phenotypic evolution in vertebrates.

Methods

Findings

Discussion

Conclusion