Social-trap or mimicry? An empirical evaluation of the Hypoplectrus unicolor–Chaetodon capistratus association in Bocas del Toro, Panama

• Published in: Coral reefs Vol. 37; no. 4; pp. 1127 - 1137
• Main Authors: Puebla, Oscar, Picq, Sophie, Lesser, Justin S., Moran, Benjamin
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-12-2018; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Body shape; Body size; Chaetodon capistratus; Colour; Conspecifics; Content analysis; Empirical analysis; Evaluation; Fish; Freshwater & Marine Ecology; Hypoplectrus unicolor; Hypotheses; Life Sciences; Marine fishes; Mimicry; Morphometry; Oceanography; Prey; Reefs; Reproductive behaviour; Stomach; Stomach content; Surveys; Sympatric populations; Panama; Resemblance; Aggressive mimicry; Social-trap; Hamlets; Reef fishes
• ISSN: 0722-4028; 1432-0975
• DOI: 10.1007/s00338-018-01741-0

Associations between resembling species have been noted long ago by naturalists and have been traditionally interpreted in terms of mimicry, whereby a mimetic species is naturally selected to resemble a model (Batesian and aggressive mimicry) or a co-mimic (Müllerian mimicry). Recently, it has been proposed that resemblances among reef fishes might be coincidental and that associations between them may result from social-traps, i.e., out-of-normal-context responses toward similar-looking individuals. The social-trap hypothesis is stimulating and calls for an in-depth reassessment of putative cases of mimicry in reef fishes. Nevertheless, an explicit field-based evaluation of these two hypotheses has yet to be conducted. Here, we test five specific predictions derived from the two hypotheses in the association between the butter hamlet (
Hypoplectrus unicolor
, Serranidae) and the foureye butterflyfish (
Chaetodon capistratus
, Chaetodontidae), which was one of the associations considered to develop the social-trap hypothesis. We present the results from 117 h of behavioral observation, 21 transect surveys covering 8400 m
2
of reef, stomach content analysis of 107 fish, morphometric analysis of 165 fish and size measurements of 386 fish from Bocas del Toro, Panama. These data indicate that (i)
C. capistratus
is 14 times more abundant than
H. unicolor
at our study site, (ii) the association with
C. capistratus
represents only 4% of
H. unicolor
’s time, (iii) the association targets
Coryphopterus
gobies in particular and deceives this prey, (iv)
H. unicolor
departs from sympatric hamlets not only in terms of color pattern but also behavior, diet, size and body shape, and (v)
H. unicolor
spends only 0.66% of its time with conspecifics out of mating contexts. We conclude that the association between
H. unicolor
and
C. capistratus
in Bocas del Toro is a true mimetic relationship, but do not rule out the possibility that a social-trap might have contributed to its evolution.