Reef-associated fishes have more maneuverable body shapes at a macroevolutionary scale

The deep sea is a hot spot of fish body shape evolution

“…First, decreasing light availability in the deep ocean is expected to impact activity patterns of fishes as well as vision‐based interactions. Second, shallow seas harbour an abundance of complex coral and rocky reef habitats that are home to a large fraction (roughly half) of the species captured in our shallow depth zone (Larouche et al, 2020). Life for fishes in these physically and biologically complex habitats likely places different demands on both swimming capabilities and feeding strategies than is experienced by fishes in the deep ocean.…”

“…Teleost fishes, with over 15,000 marine species, are distributed broadly across ocean habitats and depths (Helfman et al, 1997) and display an incredible degree of morphological diversity. Body shape is particularly variable across fishes and is often associated with factors like the hydrodynamic conditions that species typically encounter (Bejarano et al, 2017; Langerhans, 2008; Webb, 2006) and structural complexity of the habitats they occupy (Claverie & Wainwright, 2014; Friedman et al, 2020; Larouche et al, 2020). One reason for this is that body shape is thought to be associated with locomotor ability and therefore impacts how organisms capture prey and avoid predators (Mihalitsis & Bellwood, 2019; Webb, 1984), undertake large‐scale migratory movements (Kipanyula & Maina, 2016; Riddel & Leggett, 1981), and navigate structured environments (Larouche et al, 2020; Webb, 2006).…”

“…Body shape is particularly variable across fishes and is often associated with factors like the hydrodynamic conditions that species typically encounter (Bejarano et al, 2017; Langerhans, 2008; Webb, 2006) and structural complexity of the habitats they occupy (Claverie & Wainwright, 2014; Friedman et al, 2020; Larouche et al, 2020). One reason for this is that body shape is thought to be associated with locomotor ability and therefore impacts how organisms capture prey and avoid predators (Mihalitsis & Bellwood, 2019; Webb, 1984), undertake large‐scale migratory movements (Kipanyula & Maina, 2016; Riddel & Leggett, 1981), and navigate structured environments (Larouche et al, 2020; Webb, 2006). To the extent that the nature of these and other swimming‐related activities vary with respect to ocean depth, morphological traits associated with locomotion may also change accordingly.…”

“…Habitat complexity is another important factor for fish locomotion. Shallow sea environments include a number of structured habitats, many nearshore (e.g., coral and rocky reefs), that harbour large numbers of species with body plans specialized for manoeuvrability and navigation of complex surroundings (Larouche et al, 2020). Structured environments exist in the deep sea (e.g., sea mounts and hydrothermal vents) but are highly dispersed across vast expanses of relatively featureless benthic environments, like the abyssal plains (e.g., Won et al, 2003).…”

Ecological variation drives morphological differentiation in a highly social vertebrate

“…2). Deep bodies have been predicted to evolve under high risk and high structural complexity, and are expected to be counter-selected in habitats with limited shelter sizes (Webb, 1982(Webb, , 1984Brönmark & Miner, 1992;Nilsson et al, 1995;Ruehl & DeWitt, 2005;Domenici et al, 2008;Takahashi et al, 2009;Langerhans & Reznick, 2010;Ruehl et al, 2011;Larouche et al, 2020). The finding that the fish had the deepest bodies in habitats featuring high predation pressure suggests that this may serve as a morphological protection against predation risk, especially if shelter access is not hampered by a deep body.…”