How predation shaped fish: the impact of fin spines on body form evolution across teleosts

Abstract

It is well known that predators can induce morphological changes in some fish: individuals exposed to predation cues increase body depth and the length of spines. We hypothesize that these structures may evolve synergistically, as together, these traits will further enlarge the body dimensions of the fish that gape-limited predators must overcome. We therefore expect that the orientation of the spines will predict which body dimension increases in the presence of predators. Using phylogenetic comparative methods, we tested this prediction on the macroevolutionary scale across 347 teleost families, which display considerable variation in fin spines, body depth and width. Consistent with our predictions, we demonstrate that fin spines on the vertical plane (dorsal and anal fins) are associated with a deeper-bodied optimum. Lineages with spines on the horizontal plane ( pectoral fins) are associated with a wider-bodied optimum. Optimal body dimensions across lineages without spines paralleling the body dimension match the allometric expectation. Additionally, lineages with longer spines have deeper and wider body dimensions. This evolutionary relationship between fin spines and body dimensions across teleosts reveals functional synergy between these two traits and a potential macroevolutionary signature of predation on the evolutionary dynamics of body shape.

Dissecting a potential spandrel of adaptive radiation: Body depth and pectoral fin ecomorphology coevolve in Lake Malawi cichlid fishes

“…Previous hypotheses of the adaptiveness of body depth might benefit from reinterpretation in light of constructional constraints, but differences in body depth could still be advantageous in groups like Malawi cichlids for several reasons (Wainwright, Alfaro, Bolnick, & Hulsey, 2005). Increased body depth could function as an impediment to gape limited predators as has been suggested for many other species (Domenici et al, 2008;Magnhagen & Heibo, 2004;Price et al, 2015). But, it would be interesting to document whether predation differs substantially between closely related species only due to body depth or whether pectoral fin morphology might simultaneously influence their predation rates.…”

“…Both body depth and pectoral fin morphology could commonly influence critical aspects of organismal diversification such as habitat specialization (Geerlink, 1983;Gerstner, 1999;Fulton et al, 2001;Higham, 2007aHigham, , 2007bTobler et al 2008;Weese et al, 2012;Hulsey et al, 2013;Colombo et al, 2016), trophic convergence (Collar, Wainwright, & Alfaro, 2008;Krabbenhoft et al, 2009;Ruber & Adams, 2001;Rupp & Hulsey, 2014), and speciation (Elmer et al, 2010;Hendry & Taylor, 2004;Husemann et al, 2017;Pfaender et al, 2010). What also seems likely is that each trait individually influences a number of both independent and correlated behaviors across species that link morphology to species interactions (Brönmark & Miner, 1992;Bakker & Mundwiler, 1999;Hechter, Moodie, & Moodie, 2000;Wainwright et al, 2002;Pigliucci, 2003;Domenici et al, 2008;Blob et al 2010;Monteiro & Nogueira, 2010;Head et al, 2013;Price et al, 2015). Further examinations of the evolutionary associations and functions of both external and internal traits will be necessary to fully understand the phenotypic bases of adaptive radiation.…”

“…Changes in body depth could also influence a number of behaviors that link morphology to organismal behavior and functional abilities. For instance, the depth of the profile of the fish could determine susceptibility to predators (Abate, Eng, & Kaufman, ; Brönmark & Miner, ; Chivers, Zhao, Brown, Marchant, & Ferrari, ; Eklöv & Jonsson, ; Frommen et al, ; Nilsson, Brönmark, & Pettersson, ; Price, Friedman, & Wainwright, ), detection by prey (Domenici, ; Seamone, Blaine, & Higham, ; Webb, ), sexual attractiveness to mates (Head, Kozak, & Boughman, ), and swimming performance (Webb, ; Svanbäck & Eklöv, ; Domenici, Turesson, Brodersen, & Brönmark, ; Blob et al ). However, a better understanding of what internal structures are changing when fish diverge along a body depth axis could provide improved insight into the ecological, evolutionary, and functional mechanisms structuring adaptive changes in body depth.…”

Ecology shapes the evolutionary trade‐off between predator avoidance and defence in coral reef butterflyfishes

“…Given their size, their body depth lies above the 97th percentile of teleost families (based on data from Price et al . ). Our results show that in contrast to the macroevolutionary pattern found across teleosts (Price et al .…”

“…Our results show that in contrast to the macroevolutionary pattern found across teleosts (Price et al . ), body depth is constrained within butterflyfishes and has not evolved synergistically with spine length (Fig. a).…”