Competition and phylogeny determine community structure in Müllerian co-mimics

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Until recently, the study of negative and antagonistic interactions (for example, competition and predation) has dominated our understanding of community structure, maintenance and assembly1. Nevertheless, a recent theoretical model suggests that positive interactions (for example, mutualisms) may counterbalance competition, facilitating long-term coexistence even among ecologically undifferentiated species2. Müllerian mimics are mutualists that share the costs of predator education3 and are therefore ideally suited for the investigation of positive and negative interactions in community dynamics. The sole empirical test of this model in a Müllerian mimetic community supports the prediction that positive interactions outweigh the negative effects of spatial overlap4 (without quantifying resource acquisition). Understanding the role of trophic niche partitioning in facilitating the evolution and stability of Müllerian mimetic communities is now of critical importance, but has yet to be formally investigated. Here we show that resource partitioning and phylogeny determine community structure and outweigh the positive effects of Müllerian mimicry in a species-rich group of neotropical catfishes. From multiple, independent reproductively isolated allopatric communities displaying convergently evolved colour patterns, 92% consist of species that do not compete for resources. Significant differences in phylogenetically conserved traits (snout morphology and body size) were consistently linked to trait-specific resource acquisition. Thus, we report the first evidence, to our knowledge, that competition for trophic resources and phylogeny are pivotal factors in the stable evolution of Müllerian mimicry rings. More generally, our work demonstrates that competition for resources is likely to have a dominant role in the structuring of communities that are simultaneously subject to the effects of both positive and negative interactions.

At a glance


  1. Phylogenetic relationships of Corydoradinae including co-mimics.
    Figure 1: Phylogenetic relationships of Corydoradinae including co-mimics.

    The pie chart shows percentage of mimetic species per lineage. Branches with mimetic species at tips are indicated with coloured circles (coded by lineage). Nodes with support below 0.8 (Bayesian inference; BI) probability and 70% (maximum likelihood; ML) are denoted with black open circles. Codes on pictures indicate snout types as determined by morphometrics and genetic lineage (L, long; S, short; IS, intermediate short; XL, extra long; IL, intermediate long). Representative images of morphotypes and colour patterns clockwise from lineage 1: (L-1) Corydoras maculifer, (L-1) C. simulatus, (L-1) C. sp. C109, (L-1) C. sp. C92, (L-1) C. narcissus; (S-2) A. poecilius*; (L-3) S. prionotus; (IS-4) C. mamore; (IS-5) C. sp. CW19, (IS-5) C. nijsseni; (S-6) C. paleatus, (S-6) C. nattereri; (S-7) C. sp. CW26; (XL-8) C. multiradiatus*; (IS-8) C. sodalis*; (IL-8) C. imitator, (IL-8) C. sp. CW6, (IL-8) C. seussi, (IL-8) C. sp. C122; (S-9) C. sp. C91, (S-9) C. gossei, (S-9) C. adolfoi, (S-9) C. metae, (S-9) C. araguaiaensis, (S-9) C. arcuatus, (S-9) C. julii. *Non-mimetic taxa.

  2. Geographical distribution of mimetic communities.
    Figure 2: Geographical distribution of mimetic communities.

    Genetic lineages are denoted by coloured circles; small grey rectangles represent independent mimetic communities numbered 1–24. Larger black rectangles indicate communities belonging to the same drainage or basin. Grey ellipses indicate approximate geographical distribution. Species images: (1) C. paleatus, C. ehrhardti; (2) C. nattereri, Scleromystax prionotus; (3) S. barbatus, S. macropterus; (4) C. maculifer, C. sp. C122, C. araguaiaensis; (5) C. julii, C. sp. C109; (6) C. oiapoquensis, C. condisciplus; (7) C. sp. C135, C. sp. C136; (8) C. evelynae, C. sp. CW13; (9) C. kanei, C. crimmeni; (10) C. sp. CW19, C. sp. CW26; (11) C. metae, C. simulatus; (12) C. imitator, C. adolfoi, C. nijsseni; (13) C. serratus, C. cf. arcuatus; (14) C. narcissus, C. sp. CW6, C. arcuatus; (15) C. sp. C84, C. sp. C156; (16) C. sp. CW28, C. pulcher; (17) C. trilineatus, C. leopardus; (18) C. tukano, C. sp. CW11; (19) C. sp. C91, C. sp. C92; (20) C. similis, C. sp. C66, C. ourastigma; (21) C. cruziensis, C. mamore; (22) C. gossei, C. seussi; (23) C. sterbai, C. haraldshultzi; (24) C. sp. C76, C. sp. C77.


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Author information


  1. Environment Centre Wales, Molecular Ecology and Fisheries Genetics Laboratory, School of Biological Sciences, College of Natural Sciences, Bangor University, Bangor LL57 2UW, UK

    • Markos A. Alexandrou,
    • Marjorie Maillard,
    • Simon Creer &
    • Martin I. Taylor
  2. Departamento de Morfologia, Instituto de Biociencias, Universidade Estadual Paulista, 18618-970 Botucatu, SP, Brazil

    • Claudio Oliveira
  3. NERC Life Sciences Mass Spectrometry Facility, Scottish Universities Environmental Research Centre, Rankine Avenue, East Kilbride G75 0QF, UK

    • Rona A. R. McGill &
    • Jason Newton


M.I.T. conceived the study, contributed to all data collection, analysis and writing and supervised M.A.A.; M.A.A. conducted fieldwork, DNA sequencing, stable isotope analysis, morphology and colour pattern analysis, data analysis and writing. C.O. co-supervised M.A.A. and organized and participated in field sampling and writing. M.M. and R.A.R.M. conducted DNA sequencing and stable isotope analysis, respectively; J.N. provided stable isotope advice and guidance; and S.C. co-supervised M.A.A. and contributed to writing.

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The authors declare no competing financial interests.

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Sequence data have been deposited in GenBank ( with accession numbers detailed in Supplementary Table 1.

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  1. Supplementary Information (5.9M)

    This file contains Supplementary Figures 1-9 with legends and Supplementary Tables 1-4.

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