Abstract
Animal colouration is hugely diverse and functions in many adaptive ways. For instance, cryptic colouration has evolved under natural selection to prevent the detection of an animal by its predators, whilst sexual selection has favoured the evolution of conspicuous colour patterns which function in intraspecific sexual communication. Additionally, many animals are capable of changing their colouration during their life history. Colour change can occur permanently, asis often associated with ontogenetic development, or rapidly and reversibly through dynamic colour change (DCC). Research on DCC has historically focused on the cellular and molecular mechanisms underlying the phenomenon. For instance, the mechanisms of DCC are well understood in zebrafish (Danio rerio), owing to the species’ popularity as a model organism for studying colour development and regulation. However, the ultimate functions of DCC in zebrafish, among other species, have received little research attention. Here, the functions of DCC in zebrafish are investigated, considering crypsis from predators and intraspecific communication as two prevailing hypotheses. It is demonstrated that zebrafish use DCC in both crypsis and communication; individuals changed their overall colouration to more closely match the colour
of their background, and individuals also increased their internal luminance contrast when around conspecifics, which likely functions in social signalling. These results, in conjunction with existing literature on the mechanisms of DCC in zebrafish, lay the groundwork for future studies investigating the adaptive significance of DCC in fishes and other taxa. As such, we can begin integrating what is known of DCC from both proximate and ultimate perspectives, helping to build a comprehensive picture of how and why DCC has evolved and been maintained across the animal kingdom.
| Date of Award | 5 Dec 2023 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Christos C Ioannou (Supervisor) |