Getting in shape: habitat-based morphological divergence for two sympatric fishes

Abstract

Freshwater fishes often show large amounts of body shape variation across divergent habitats and, in most cases, the observed differences have been attributed to the environmental pressures of living in lentic or lotic habitats. Previous studies have suggested a distinct set characters and morphological features for species occupying each habitat under the steady–unsteady swimming performance model. We tested this model and assessed body shape variation using geometric morphometrics for two widespread fishes, Goodea atripinnis (Goodeidae) and Chirostoma jordani (Atherinopsidae), inhabiting lentic and lotic habitats across the Mesa Central of Mexico. These species were previously shown to display little genetic variation across their respective ranges. Our body shape analyses reveal morphometric differentiation along the same axes for both species in each habitat. Both possess a deeper body shape in lentic habitats and a more streamlined body in lotic habitats, although the degree of divergence between habitats was less for C. jordani. Differences in the position of the mouth differed between habitats as well, with both species possessing a more superior mouth in lentic habitats. These recovered patterns are generally consistent with the steady–unsteady swimming model and highlight the significance of environmental forces in driving parallel body shape differences of organisms in divergent habitats. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114, 152–162.

Genetic composition of a population of natural common bream Abramis brama × roach Rutilus rutilus hybrids and their morphological characteristics in comparison with parent species

“…Thus, these species must efficiently perform both long-distance steady swimming and local unsteady swimming. Diet composition and habitat structural complexity are principal factors shaping fish morphology (most recently Foster et al, 2015;Prado et al, 2016;Restrepo-Escobar et al, 2016;Lazzarotto et al, 2017;Siqueira-Souza et al, 2017). Anatomically, relative trunk and tail lengths are related to the absolute number, size and relative distribution of vertebrae.…”

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“…The specimens from the Borač and Grošnica upper flows showed lower body depth, a sharper snout and a more spindle-shaped body than specimens from the Petrovačka and Grošnica lower flows. This is specific to lotic environments since they tend to select a body shape that reduces drag because a fusiform shape reduces resistance in aquatic environments, allowing effective propulsion and maintenance of velocity at a lower energy cost (Webb, 1984;Langerhans & Reznick, 2009;Foster et al, 2015). A certain degree of differentiation between two localities from the Grošnica River, above the dam and below the lake, was also detected.…”

“…The differences in the morphometry of B. balcanicus between the Borаč River and Petrovačka River could be due to their belonging to different river basins and their lack of connectivity. Differences in prey type and abundance between different habitats may have given rise to morphological character diversification, such as mouth position and head size (Foster et al, 2015), which is noticeable among groups of both sexes. Considering that environmental conditions between the localities were not greatly different (Tukey's HSD, p > 0.05), the observed morphological divergence may be partly attributed to stream damming, which acts as a stressor and permanently alters the systems, shifting them into a new ecological medium.…”

Body-shape variation ofAcroneuria lycorias(Plecoptera∶Perlidae) nymphs across magnitude and frequency stream flows

“…Nevertheless, flow regime components are the major abiotic variable in stream systems and their linkage to other stream organisms is well documented. Fish in streams possess a much more elongated (streamlined) body shape than individuals of the same species in lake systems (Foster et al 2015). Bullhead Minnows (Pimephales vigilax) in a reservoir above a dam showed a rapid morphological shift to increased body depth relative to populations in the stream below the dam (Cureton and Broughton 2014).…”