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. 2014 Mar 6;9(3):e89832.
doi: 10.1371/journal.pone.0089832. eCollection 2014.

Morphology and Efficiency of a Specialized Foraging Behavior, Sediment Sifting, in Neotropical Cichlid Fishes

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Free PMC article

Morphology and Efficiency of a Specialized Foraging Behavior, Sediment Sifting, in Neotropical Cichlid Fishes

Hernán López-Fernández et al. PLoS One. .
Free PMC article

Abstract

Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis on a set of ecomorphological traits from 27 species of Neotropical cichlids. For most sifting taxa, feeding behavior could be effectively predicted by a linear discriminant function of ecomorphology across multiple clades of sediment sifters, and this pattern could not be explained by shared evolutionary history alone. Additionally, we tested foraging efficiency in seven Neotropical cichlid species, five of which are specialized benthic feeders with differing head morphology. Efficiency was evaluated based on the degree to which invertebrate prey could be retrieved at different depths of sediment. Feeding performance was compared both with respect to feeding mode and species using a phylogenetic ANCOVA, with substrate depth as a covariate. Benthic foraging performance was constant across sediment depths in non-sifters but declined with depth in sifters. The non-sifting Hypsophrys used sweeping motions of the body and fins to excavate large pits to uncover prey; this tactic was more efficient for consuming deeply buried invertebrates than observed among sediment sifters. Findings indicate that similar feeding performance among sediment-sifting cichlids extracting invertebrate prey from shallow sediment layers reflects constraints associated with functional morphology and, to a lesser extent, phylogeny.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Species of Neotropical cichlids used in foraging experiments.
A Geophagus cf. brachybranchus, B ‘Geophagussteindachneri, C Mikrogeophagus altispinosus, D Satanoperca daemon, E Thorichthys ellioti (picture shown is of the congeneric T. cf meeki), F Amatitlania siquia, G Hypsophrys nematopus. Phylogeny and times of divergence follow López-Fernández et al. .
Figure 2
Figure 2. Linear discriminant function analysis (LDA) of morphological attributes in 27 species of Neotropical cichlids.
LDA produced an axis of variation that effectively separated non-sifters (top panel) from specialized sediment-sifting species (bottom panel) by their morphological attributes. Among sediment-sifters, the model distribution to the left represents individuals “misclassified” by the LDA analysis as non-sifters, including Thorichthys ellioti (5/5), Mikrogeophagus ramirezi (4/4) and Biotodoma wavrini (1/5). Images marked with an “*” depict genera used in feeding efficiency experiments.
Figure 3
Figure 3. Mean consumption of chironomid larvae buried at 0, 1, 2, or 3-sifting (2 species) and sediment-sifting (5) Neotropical cichlids.
Consumption by each species is illustrated in S2.
Figure 4
Figure 4. Mean consumption of chironomid larvae buried at 0, 1, 2, or 3 cm depth by the heroine Neotropical cichlid Hypsophrys nematopus.
Even (filled circles) versus clumped (empty triangles) distributions. The horizontal line indicates weight loss of chironomid larvae in control tanks.

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Grant support

Funding for this project was provided by the NSF Undergraduate Mentoring in Environmental Biology Program (grant #0203992), NSF DEB grant #0516831 to KOW, RLH and HLF, and by an NSERC Discovery Grant to HLF. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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