A Sensory Bias Has Triggered the Evolution of Egg-Spots in Cichlid Fishes

Egger, Bernhard; Klaefiger, Yuri; Theis, Anya; Salzburger, Walter

doi:10.1371/journal.pone.0025601

Cited by 43 publications

(33 citation statements)

References 32 publications

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“…The egg spots (yellow anal fin patches thought to mimic eggs) of male cichlids have been reported to influence several behaviours, including male–male aggression, mate choice and fertilization (Wickler ; Hert ; Egger et al . ; Theis et al . ).…”

Section: Discussionmentioning

confidence: 99%

Variable light environments induce plastic spectral tuning by regional opsin coexpression in the African cichlid fish, Metriaclima zebra

Dalton

Leips

et al. 2015

Molecular Ecology

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Critical behaviors such as predation and mate choice often depend on vision. Visual systems are sensitive to the spectrum of light in their environment, which can vary extensively both within and among habitats. Evolutionary changes in spectral sensitivity contribute to divergence and speciation. Spectral sensitivity of the retina is primarily determined by visual pigments, which are opsin proteins bound to a chromophore. We recently discovered that photoreceptors in different regions of the retina, which view objects against distinct environmental backgrounds, coexpress different pairs of opsins in an African cichlid fish, Metriaclima zebra. This coexpression tunes the sensitivity of the retinal regions to the corresponding backgrounds and may aid detection of dark objects, such as predators. Although intraretinal regionalization of spectral sensitivity in many animals correlates with their light environments, it is unknown whether variation in the light environment induces developmentally plastic alterations of intraretinal sensitivity regions. Here, we demonstrate with fluorescent in situ hybridization and qPCR that the spectrum and angle of environmental light both influence the development of spectral sensitivity regions by altering the distribution and level of opsins across the retina. Normally M. zebra coexpresses LWS opsin with RH2Aα opsin in double cones of the ventral but not the dorsal retina. However, when illuminated from below throughout development, adult M. zebra coexpressed LWS and RH2Aα in double cones both dorsally and ventrally. Thus, environmental background spectra alter the spectral sensitivity pattern that develops across the retina, potentially influencing behaviors and related evolutionary processes such as courtship and speciation.

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Section: Discussionmentioning

confidence: 99%

Variable light environments induce plastic spectral tuning by regional opsin coexpression in the African cichlid fish, Metriaclima zebra

Dalton

Leips

et al. 2015

Molecular Ecology

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“…A. elegans [175]; Pseudotropheus aurora [177]; P. lombardi [178]), but in other species this is not the case ( A. burtoni [176,179]). Interestingly, female Pseudocrenilabrus multicolor prefer males with spots, even though their own males don’t have them, possibly indicating an ancestral sensory bias [180]. Finally, there is some evidence that eggspots may have an intimidating effect in aggressive interactions in A. burtoni [176,179].…”

Section: Figmentioning

confidence: 99%

Colour variation in cichlid fish: Developmental mechanisms, selective pressures and evolutionary consequences

Maan

Sefc

2013

Seminars in Cell & Developmental Biology

181

149

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Cichlid fishes constitute one of the most species-rich families of vertebrates. In addition to complex social behaviour and morphological versatility, they are characterised by extensive diversity in colouration, both within and between species. Here, we review the cellular and molecular mechanisms underlying colour variation in this group and the selective pressures responsible for the observed variation. We specifically address the evidence for the hypothesis that divergence in colouration is associated with the evolution of reproductive isolation between lineages. While we conclude that cichlid colours are excellent models for understanding the role of animal communication in species divergence, we also identify taxonomic and methodological biases in the current research effort. We suggest that the integration of genomic approaches with ecological and behavioural studies, across the entire cichlid family and beyond it, will contribute to the utility of the cichlid model system for understanding the evolution of biological diversity.

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“…Variation in size, number, and color of the egg-spots has been observed both between and within species ). Egg-spots appear to play a prominent role in mating behavior (Wickler 1962), although their exact function remains elusive (Egger et al 2011;Theis et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Molecular Characterization of Two Endothelin Pathways in East African Cichlid Fishes

Diepeveen

Salzburger

2011

J Mol Evol

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The adaptive radiations of cichlid fishes in East Africa have been associated with the acquisition of evolutionary novelties as well as the ecological opportunities existing in the East African Great lakes. Two remarkable evolutionary innovations are the pharyngeal jaw apparatus, found in all cichlid species, and the anal fin egg-spots of mouthbrooding cichlids. Based on their conserved functions during the development of both the jaw apparatus and pigmentation, the endothelin ligands and receptors form a putative link between these naturally and sexually selected traits. Here we study the evolutionary history of four members of two endothelin pathways (Edn1/EdnrAa and Edn3b/EdnrB1a) to elucidate their possible roles during the evolution and development of key innovations in East African cichlids species. The analyses performed on partial sequences (ca. 6,000 bp per taxon) show that all four endothelin family members evolved under purifying selection, although both ligands are characterized by an accelerated rate of protein evolution in comparison to the receptors. In accordance with earlier findings, we show that the mature protein sequence of Edn1 and Edn3 are highly conserved, also in cichlids, whereas the preproendothelin parts are variable indicating relaxed selective constraints. In the receptors, nonsynonymous substitutions were mainly found in the ligand-binding domains suggesting functional divergence. Gene expression assays with Real-Time PCR indeed reveal that the two studied endothelin pathways are expressed in the cichlid pharyngeal jaw and in the haplochromine egg-spot (among other pigment-cell containing tissues), suggesting their involvement during morphogenesis of naturally and sexually selected traits in cichlids.

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A Sensory Bias Has Triggered the Evolution of Egg-Spots in Cichlid Fishes

Cited by 43 publications

References 32 publications

Variable light environments induce plastic spectral tuning by regional opsin coexpression in the African cichlid fish, Metriaclima zebra

Variable light environments induce plastic spectral tuning by regional opsin coexpression in the African cichlid fish, Metriaclima zebra

Colour variation in cichlid fish: Developmental mechanisms, selective pressures and evolutionary consequences

Molecular Characterization of Two Endothelin Pathways in East African Cichlid Fishes

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