Developmental plasticity and variability in the formation of egg‐spots, a pigmentation ornament in the cichlid Astatotilapia calliptera

Research output: Contribution to journalResearch articleContributedpeer-review


  • Bethan Clark - , University of Cambridge (Author)
  • Aaron Hickey - , University of Cambridge (Author)
  • Aleksandra Marconi - , University of Cambridge (Author)
  • Bettina Fischer - , University of Cambridge (Author)
  • Joel Elkin - , University of Cambridge (Author)
  • Rita Mateus - , Tissue Organization and Dynamics (with MPI-CBG) (Junior Research Group), Max Planck Institute of Molecular Cell Biology and Genetics (Author)
  • M. Emília Santos - , University of Cambridge (Author)


Vertebrate pigmentation patterns are highly diverse, yet we have a limited understanding of how evolutionary changes to genetic, cellular, and developmental mechanisms generate variation. To address this, we examine the formation of a sexually-selected male ornament exhibiting inter- and intraspecific variation, the egg-spot pattern, consisting of circular yellow-orange markings on the male anal fins of haplochromine cichlid fishes. We focus on Astatotilapia calliptera, the ancestor-type species of the Malawi cichlid adaptive radiation of over 850 species. We identify a key role for iridophores in initializing egg-spot aggregations composed of iridophore-xanthophore associations. Despite adult sexual dimorphism, aggregations initially form in both males and females, with development only diverging between the sexes at later stages. Unexpectedly, we found that the timing of egg-spot initialization is plastic. The earlier individuals are socially isolated, the earlier the aggregations form, with iridophores being the cell type that responds to changes to the social environment. Furthermore, we observe apparent competitive interactions between adjacent egg-spot aggregations, which strongly suggests that egg-spot patterning results mostly from cell-autonomous cellular interactions. Together, these results demonstrate that A. calliptera egg-spot development is an exciting model for investigating pigment pattern formation at the cellular level in a system with developmental plasticity, sexual dimorphism, and intraspecific variation. As A. calliptera represents the ancestral bauplan for egg-spots, these findings provide a baseline for informed comparisons across the incredibly diverse Malawi cichlid radiation.


Original languageEnglish
Article numbere12475
JournalEvolution & Development
Issue number3
Early online date30 Mar 2024
Publication statusPublished - May 2024

External IDs

unpaywall 10.1111/ede.12475
Scopus 85189614147
Mendeley 13f1c858-84b8-396f-9eb8-1bba61e01a88



  • developmental plasticity, pigment pattern formation, cichlids