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The evolution of mimicry of friarbirds by orioles (Aves: Passeriformes) in Australo-Pacific archipelagos

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Observations by Alfred Wallace and Jared Diamond of plumage similarities between co-occurring orioles (Oriolus) and friarbirds (Philemon) in the Malay archipelago led them to conclude that the former represent visual mimics of the latter. Here, we use molecular phylogenies and plumage reflectance measurements to test several key predictions of the mimicry hypothesis. We show that friarbirds originated before brown orioles, that the two groups did not co-speciate, although there is one plausible instance of co-speciation among species on the neighbouring Moluccan islands of Buru and Seram. Furthermore, we show that greater size disparity between model and mimic and a longer history of co-occurrence have resulted in a stronger plumage similarity (mimicry). This suggests that resemblance between orioles and friarbirds represents mimicry and that colonization of islands by brown orioles has been facilitated by their ability to mimic the aggressive friarbirds.
Cite this article: Jønsson KA, Delhey K,
Sangster G, Ericson PGP, Irestedt M. 2016
The evolution of mimicry of friarbirds
by orioles (Aves: Passeriformes) in
Australo-Pacific archipelagos. Proc. R. Soc. B
283: 20160409.
Received: 23 February 2016
Accepted: 25 May 2016
Subject Areas:
ecology, evolution
Australo-Papua, coexistence,
community assembly, competition,
island biogeography, molecular phylogeny
Author for correspondence:
Knud Andreas Jønsson
Electronic supplementary material is available
at or
The evolution of mimicry of friarbirds
by orioles (Aves: Passeriformes) in
Australo-Pacific archipelagos
Knud Andreas Jønsson1,2, Kaspar Delhey3,4, George Sangster5,6,
Per G. P. Ericson5and Martin Irestedt6
Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of
Copenhagen, 2100 Copenhagen Ø, Denmark
Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UK
School of Biological Sciences, Monash University, Clayton Campus, Clayton, 3800 Victoria, Australia
Max Planck Institute for Ornithology, Radolfzell 78315, Germany
Department of Zoology, and
Department of Bioinformatics and Genetics, Swedish Museum of Natural History,
PO Box 50007, Stockholm 10405, Sweden
Observations by Alfred Wallace and Jared Diamond of plumage similarities
between co-occurring orioles (Oriolus) and friarbirds (Philemon) in the Malay
archipelago led them to conclude that the former represent visual mimics of
the latter. Here, we use molecular phylogenies and plumage reflectance
measurements to test several key predictions of the mimicry hypothesis. We
show that friarbirds originated before brown orioles, that the two groups
did not co-speciate, although there is one plausible instance of co-speciation
among species on the neighbouring Moluccan islands of Buru and Seram.
Furthermore, we show that greater size disparity between model and mimic
and a longer historyof co-occurrence have resulted in a stronger plumage simi-
larity (mimicry). This suggests that resemblance between orioles and friarbirds
represents mimicry and that colonization of islands by brown orioles has been
facilitated by their ability to mimic the aggressive friarbirds.
1. Introduction
Species may resemble each other in appearance for various reasons. For example,
closely related species may not have had sufficient time to diverge phenotypi-
cally, or convergence may lead to a similar appearance across distantly related
species. This could have developed in the course of millions of years either
by random chance or because a given design (shape or colour) is favoured in a
particular habitat or environment. Alternatively, mimicry may increase the
resemblance of one species (mimic) to another (the model), thereby leading to
an advantage for the mimic or for both species [1,2].
Interspecific social dominance mimicry (ISDM) is a proposed form of social
parasitism in which a subordinate species evolves to mimic and deceive a domi-
nant ecological competitor to avoid attack by the dominant model species.
Among the roughly 10 000 species of birds, there may be about 50 phylogenetically
independent origins of visual ISDM (reviewed by Prum [3]), and game-theoretic
models have shown the plausibility of this hypothesis [4]. However, few of these
putative cases have been investigated in detail.
Wallace [5] wasthe first, to the best of our knowledge, to describe visual mimi-
cry between orioles (Oriolus, Oriolidae) and friarbirds (Philemon,Meliphagidae)in
the Moluccan islands. He suggested that orioles could avoid attack by hawks by
mimicking the aggressive friarbirds. Stresemann [6] disputed the mimicry claim,
which he thought was simply the result of convergent evolution (“Resultat unab-
¨ngiger Convergenz der Entwicklungsrichtungen”). More recently, Diamond [7]
provided a detailed account of the various explanations of the mimicry between
orioles and friarbirds and based on field observations suggested that orioles do
mimic the friarbirds to avoid attack from the friarbirds when feeding in the
&2016 The Author(s) Published by the Royal Society. All rights reserved.
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