Transcriptomics of morphological color change in polychromatic Midas cichlids

Area of Science:

• Evolutionary Biology
• Genetics
• Developmental Biology

Background:

• Animal pigmentation is crucial for adaptation and speciation, but underlying genetic changes are often unknown.
• Midas cichlids exhibit ontogenetic color change, making them a model for studying pigmentation evolution and speciation.
• This color change may also inform research into human pigmentation disorders.

Purpose of the Study:

• To investigate the genetic underpinnings of color change in Midas cichlids using transcriptomic analysis.
• To identify differentially expressed genes associated with pigmentation differences and speciation.
• To explore potential parallels with human skin disorders.

Main Methods:

• RNA sequencing (RNAseq) of skin transcriptome from Midas cichlids at three color transformation stages.
• Comparative analysis of gene expression levels across different color morphs using differential expression analyses.
• Genetic cross to validate gene association with phenotype.

Main Results:

• Identified 46 candidate differentially expressed genes between Midas cichlid color morphs.
• Found melanosomal pathway genes upregulated in normally pigmented fish.
• Observed upregulation of immediate early and inflammatory response genes in transitional fish, similar to human skin disorders.

Conclusions:

• Transcriptomic analysis successfully identified key gene expression differences related to Midas cichlid color morphs.
• These findings advance understanding of speciation mechanisms driven by color polymorphism and sexual selection.
• Identified genes and their human orthologs may serve as markers for human pigmentation disorders.