Figure 1.

Figure 1.

(A) Examples of major carotenoid types including yellow zeaxanthin, red astaxanthin, and orange β-carotene, with factors required for entry into cells and chemical modification (Main text). (B) Erythrophore presence (red circles) or absence (light gray circles) indicated by direct observation or prior species descriptions (Fang and Kottelat, 2000; Quigley et al., 2005; Engeszer et al., 2007; Kullander and Fang, 2009; Kullander, 2012; Kullander and Norén, 2016; Spiewak et al., 2018; McCluskey et al., 2021). A composite phylogeny based on several molecular evolutionary studies is shown; gray branches indicate lineage placements inferred by morphology alone (Tang et al., 2010; Kullander, 2012; Kullander et al., 2015; McCluskey and Postlethwait, 2015). Gray boxes across branches indicate lineages in which erythrophores are inferred most parsimoniously to have been lost. (C) Anal fin details of zebrafish (rerio) without erythrophores and other species with erythrophores. Cells are shown in their typical native states, with pigment dispersed, and following treatment with epinephrine, which causes pigment to be contracted toward cell centers. Scale bar: 100 μm.