Animals often change their habitat throughout ontogeny; yet, the triggers for habitat transitions and how these correlate with developmental changes – e.g. physiological, morphological and behavioural – remain largely unknown. Here, we investigated how ontogenetic changes in body coloration and of the visual system relate to habitat transitions in a coral reef fish. Adult dusky dottybacks, Pseudochromis fuscus, are aggressive mimics that change colour to imitate various fishes in their surroundings; however, little is known about the early life stages of this fish. Using a developmental time series in combination with the examination of wild-caught specimens, we revealed that dottybacks change colour twice during development: (i) nearly translucent cryptic pelagic larvae change to a grey camouflage coloration when settling on coral reefs; and (ii) juveniles change to mimic yellow- or brown-coloured fishes when reaching a size capable of consuming juvenile fish prey. Moreover, microspectrophotometric (MSP) and quantitative real-time PCR (qRT-PCR) experiments show developmental changes of the dottyback visual system, including the use of a novel adult-specific visual gene (RH2 opsin). This gene is likely to be co-expressed with other visual pigments to form broad spectral sensitivities that cover the medium-wavelength part of the visible spectrum. Surprisingly, the visual modifications precede changes in habitat and colour, possibly because dottybacks need to first acquire the appropriate visual performance before transitioning into novel life stages.
The authors declare no competing or financial interests.
F.C. conceived the study and designed the experiments together with N.J.M., K.L.C. and W.S. F.C., Z.M., S.M.S., N.S.H. and U.E.S. performed the experiments and analysed the data. F.C., Z.M., K.L.C., W.S. and N.J.M. wrote the initial manuscript. All authors reviewed and approved the final version of the manuscript.
F.C. was supported by an Australian Endeavour Research Fellowship (2012), Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung Doctoral Mobility and Early Postdoctoral Mobility Fellowships (148460; 165364), and a Doctoral Fellowship (2013) from the Lizard Island Research Station, a facility of the Australian Museum; Z.M. was supported by Novartis – Universität Basel Excellence Scholarship for Life Sciences; S.M.S. was supported by the German Academic Exchange Service (Deutscher Akademischer Austauschdienst) (2012–2014); N.S.H. was supported by an Australian Research Council QEII Research Fellowship (DP0558681); U.E.S was supported by an Australian Research Council APD Fellowship (DP557285); K.L.C. was supported by the University of Queensland and the Australian Research Council; W.S. was supported by the Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung and the European Research Council; and N.J.M. was supported by the Australian Research Council.
Supplementary information available online at http://jeb.biologists.org/lookup/doi/10.1242/jeb.139501.supplemental
- Received February 22, 2016.
- Accepted June 9, 2016.
- © 2016. Published by The Company of Biologists Ltd