Variation on a theme: pigmentation variants and mutants of anemonefish

Abstract

Pigmentation patterning systems are of great interest to understand how changes in developmental mechanisms can lead to a wide variety of patterns. These patterns are often conspicuous, but their origins remain elusive for many marine fish species. Dismantling a biological system allows a better understanding of the required components and the deciphering of how such complex systems are established and function. Valuable information can be obtained from detailed analyses and comparisons of pigmentation patterns of mutants and/or variants from normal patterns. Anemonefishes have been popular marine fish in aquaculture for many years, which has led to the isolation of several mutant lines, and in particular color alterations, that have become very popular in the pet trade. Additionally, scattered information about naturally occurring aberrant anemonefish is available on various websites and image platforms. In this review, the available information on anemonefish color pattern alterations has been gathered and compiled in order to characterize and compare different mutations. With the global picture of anemonefish mutants and variants emerging from this, such as presence or absence of certain phenotypes, information on the patterning system itself can be gained.

Anemonefishes: A model system for evolutionary genomics

“…49,50 Such rearing methods and intrinsic features of anemonefish has expanded their potential as a model organism by opening new avenues for the use of molecular tools (e.g., microinjections 51,52 ), functional approaches, and ecotoxicological and/or pharmacological experiments (reviewed in 2 ). Crosses can be performed in the laboratory 16 and anemonefish can spawn every two to three weeks, typically laying between 100 and 500 eggs on the substrate near their host anemone (Figure 2d). Further, they have a short embryonic and larval development (which have been characterized in precise detail 53,54 ) of 10-15 days (depending on the water temperature and the species), thus allowing large-scale studies.…”

“…95 The clownfish is a conspicuously colored species (possessing a bright orange body with three iridescent white bars bordered with black), and understanding the molecular basis of pigmentation has also become a fundamental question of evolutionary biology. 2,14,16,96 Studies on A. ocellaris and A. percula have provided insights on how pigmentation patterns are phylogenetically conserved but also exhibit developmental and environmental plasticity. 15,86 Other applications of transcriptomics in anemonefish research have provided in-depth characterization of visual opsins 59,77,87 and the rhythmic expression of internal clock genes.…”

“…We then present a detailed synthesis of recent research that has provided important insights into the incredible adaptive radiation anemonefish have undergone, [7][8][9][10][11] and how their genomic architecture underlies the evolution of complex phenotypic traits such as sex change 12,13 and color patterning. [14][15][16] We further describe how researchers are using anemonefish as a model system to understand the genomic basis of symbiosis with giant sea anemones 10,[17][18][19] and environmental plasticity. 20,21 2.…”

Harbours as unique environmental sites of multiple anthropogenic stressors on fish hormonal systems

“…Indeed, thyroid hormones (TH, notably thyroxine (T4) and triiodothyronine (T3)); Holzer et al, 2017) and cortisol (Jesus et al, 1991) act in concert to control and modulate metamorphosis. TH levels increase during post-embryonic development to reach a peak which induces metamorphosis; TH then coordinate ontogenetic transformations from the larval to the juvenile stages (Gilbert et al, 1996;Wada, 2008;Isorna et al, 2009;McMenamin and Parichy, 2013;Campinho, 2019;Klann et al, 2021). As TH signalling is critical for neurogenesis and the development of sensory organs, it may play a role in determining the "quality" of future juveniles, i.e., their capacity to select suitable habitats, feed efficiently, as well as detect predators and escape from them, which are all crucial for fish to successfully recruit into adult populations (Besson et al, 2020).…”

Colour patterns influence symbiosis and competition in the anemonefish–host anemone symbiosis system

“…This hypothesis is supported by the fact that the differences in the number of white bars between species inhabiting the same area are significantly greater than would be expected at random [27]. In addition, anemonefish patterns change during ontogeny in some species [7,[23][24][25]27], and the different patterns of juveniles from adults may be a dishonest signal to conceal their presence and reduce agonistic interactions [26,27,30]. The second hypothesis is that the contrast of the bright base colour and white stripes is disruptive and functions to hide the fish silhouette.…”