Non-sex-linked color polymorphism is common in animals and can be maintained in populations via balancing selection or, when under diversifying selection, can promote divergence. Despite their potential importance in ecological interactions and the evolution of biodiversity, their function and the mechanisms by which these polymorphisms are maintained are still poorly understood. Here, we combine field observations with life history and molecular data to compare four sympatric color morphs of the coral reef fish Paracirrhites forsteri (family Cirrhitidae) in the central Red Sea. Our findings verify that the color morphs are not sex-limited, inhabit the same reefs, and do not show clear signs of avoidance or aggression among them. A barcoding approach based on 1,276 bp of mitochondrial DNA could not differentiate the color morphs. However, when 36,769 SNPs were considered, we found low but significant population structure. Focusing on 1,121 FST outliers, we recovered distinct population clusters that corresponded to shifts in allele frequencies with each color morph harboring unique alleles. Genetic divergence at these outlier loci is accompanied by differences in growth and marginal variation in microhabitat preference. Together, life history and molecular analysis suggest subtle divergence between the color morphs in this population, the causes for which remain elusive.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): CRG-1-2012-BER-002
Acknowledgements: This study was supported by KAUST Award No. CRG-1-2012-BER-002 and baseline research funds to M.L.B., an Environment and Agriculture Visiting Scholar Scheme (EAVSS) Fellowship at Curtin University to M.R.G., and startup funding from the University of Central Florida to M.R.G. For logistic support in Saudi Arabia, we thank Eric Mason at Dream Divers, the KAUST Coastal and Marine Resources Core Lab, and Amr Gusti, as well as members of the Reef Ecology Lab at KAUST. For assistance with library preparation at KAUST, we thank Craig Michell. We acknowledge important contributions from Lutz Froenicke and the staff at the UC Davis Genome Center. We also thank Pablo Saenz-Agudelo for help in testing structure runs with their computing cluster at the Austral University of Chile and Shelley Jones for her assistance with taxonomic research.