Molekulare Mechanismen der Entstehung und Evolution von Farbmustern in Buntbarschen.

• Antragsteller: Professor Dr. Claudius Kratochwil
• Fachliche Zuordnung: Evolutionäre Zell- und Entwicklungsbiologie der Tiere ; Allgemeine Genetik und funktionelle Genomforschung ; Evolution, Anthropologie
• Förderung: Förderung von 2019 bis 2022
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 423396155

• Erstellungsjahr: 2022

Zusammenfassung der Projektergebnisse

The adaptive radiations of cichlids with their famously diverse and colorful species provide an excellent opportunity to study the genetic basis of color patterns, their diversification and repeated (i.e. convergent and/or parallel) evolution. Cichlids are an exceptional model system to study the genotype-phenotype relationships. They have several practical advantages, the most powerful being the possibility for forward genetics, functional experiments and the possibility to observe color patterns already in early larvae. Aim of this study was to integrate forward genetics, molecular analyses, genome editing, phylogenetic approaches, and behavioral assays to uncover the genomic and mechanistic substrates of color patterns, their function and their astonishing evolutionary dynamics. The specific aim was to investigate color patterns at different levels of biological organization by studying a) the genetic basis of color patterns, b) studying how patterns are formed at a cellular level through the multi-layered vertical arrangements of pigment cells within the skin and c) to obtain insights into the selective forces driving the evolution of these patterns. By conducting a hybrid cross in Lake Malawi cichlids we could identify the genomic basis of stripe and bar patterns and show how incremental fine-tuning through the evolution of additional modifier loci might have influenced the evolution of color patterns. Genomic analysis also provided more in-depth genetic insights into the independent recruitment of regulatory alleles that control the “stripe gene” agrp2. A particularly noteworthy discovery is also that the evolution of the alleles that underlie stripe-non-stripe divergence in the >500 species cichlid radiation precedes the adaptive radiation. We could also show that agrp2 seems to be also involved in stripe pattern formation outside of East African cichlids providing a macroevolutionary perspective on the evolution of this common color pattern. Moreover, work supported by this grant gave insights into the cellular processes that shape color patterns in cichlid fishes. Lastly, an integrative analysis of the evolution of stripe patterns in cichlid fishes demonstrated that its evolution is frequent, correlated with the evolution of body morphology and likely not linked to sexual selection and mate choice. In summary this project identified genomic, mechanistic and functional underpinnings of color pattern diversification and repeated evolution in cichlid fishes. It addressed fundamental questions regarding the genomic architecture of repeatedly evolved traits, modular trait architecture as well as the adaptive function of color patterns. The results thereby gave insights into how genetic variations translate to complex phenotypic changes. Through integrating genetic, molecular, developmental, behavioral and evolutionary concepts and approaches we are now able to more comprehensive understand the repeated and diversifying evolution of coloration phenotypes.

Projektbezogene Publikationen (Auswahl)

• Contrasting signatures of genomic divergence during sympatric speciation. Nature, 588(7836), 106-111.
  Kautt, Andreas F.; Kratochwil, Claudius F.; Nater, Alexander; Machado-Schiaffino, Gonzalo; Olave, Melisa; Henning, Frederico; Torres-Dowdall, Julián; Härer, Andreas; Hulsey, C. Darrin; Franchini, Paolo; Pippel, Martin; Myers, Eugene W. & Meyer, Axel
  
• Developmental and Cellular Basis of Vertical Bar Color Patterns in the East African Cichlid Fish Haplochromis latifasciatus. Frontiers in Cell and Developmental Biology, 8.
  Liang, Yipeng; Gerwin, Jan; Meyer, Axel & Kratochwil, Claudius F.
  
• Different Sources of Allelic Variation Drove Repeated Color Pattern Divergence in Cichlid Fishes. Molecular Biology and Evolution, 38(2), 465-477.
  Urban, Sabine; Nater, Alexander; Meyer, Axel & Kratochwil, Claudius F.
  
• Neural innervation as a potential trigger of morphological color change and sexual dimorphism in cichlid fish. Scientific Reports, 10(1).
  Liang, Yipeng; Meyer, Axel & Kratochwil, Claudius F.
  
• Functional conservation and divergence of color‐pattern‐related agouti family genes in teleost fishes. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution, 336(5), 443-450.
  Liang, Yipeng; Grauvogl, Maximilian; Meyer, Axel & Kratochwil, Claudius F.
  
• Of bars and stripes: A Malawi cichlid hybrid cross provides insights into genetic modularity and evolution of modifier loci underlying colour pattern diversification. Molecular Ecology, 30(19), 4789-4803.
  Gerwin, Jan; Urban, Sabine; Meyer, Axel & Kratochwil, Claudius F.
  
• An intronic transposon insertion associates with a trans-species color polymorphism in Midas cichlid fishes. Nature Communications, 13(1).
  Kratochwil, Claudius F.; Kautt, Andreas F.; Nater, Alexander; Härer, Andreas; Liang, Yipeng; Henning, Frederico & Meyer, Axel
  
• The repeated evolution of stripe patterns is correlated with body morphology in the adaptive radiations of East African cichlid fishes. Ecology and Evolution, 12(2).
  Urban, Sabine; Gerwin, Jan; Hulsey, C. Darrin; Meyer, Axel & Kratochwil, Claudius F.