Coloration plays key roles in fundamental physiological, ecological, and evolutionary processes. We study coloration phenotypes to gain an integrative understanding of how genetic, developmental, and cellular changes lead to evolutionary diversification.
The research of our lab is currently focusing on two lines of research:
Cichlid fishes are an excellent model system for understanding phenotypic diversification from a genomic standpoint. They are a famous example of explosive adaptive radiation — in less than a few million years over 1,200 species evolved in the three East African Lakes Victoria, Tanganyika, and Malawi. This astonishing rate of diversification makes them a suitable family of vertebrates to investigate the genetic changes associated with the diversification of traits, including coloration.
Coloration is undoubtedly one of the traits that strongly affected the adaptation and exceptional rate of speciation. The exceptional degree of phenotypic diversification we find in cichlids is only associated with a very low degree of genetic diversification. As a result of recent divergence, many cichlids can be hybridized permitting Quantitative Loci Mapping (QTL) studies. Also, we established a state-of-the-art toolset including Crispr-Cas9 mutagenesis and Tol2-transgenesis that allow us to confirm and further investigate target genes and mutations. We take advantage of this exceptional model system to study fascinating genotype-phenotype relationships.
Relevant publications:
Claudius Kratochwil, Yipeng Liang, Jan Gerwin, Joost Woltering, Sabine Urban, Frederico Henning, Gonzalo Machado-Schiaffino, Darrin Hulsey, and Axel Meyer (2018). Agouti-related peptide 2 facilitates convergent evolution of stripe patterns across cichlid fish radiations. Science 362:457–460.
Andreas Kautt*, Claudius Kratochwil*, Alexander Nater*, Gonzalo Machado-Schiaffino, Melisa Olave, Frederico Henning, Julián Torres-Dowdall, Andreas Härer, Darrin Hulsey, Paolo Franchini, Martin Pippel, Gene Myers, and Axel Meyer (2020): Contrasting signatures of genomic divergence during sympatric speciation. Nature 588:106-111.
The color of tissues results from the multi-layered organization of pigment cell types with different structural and pigmentary properties. On a macroscopic scale, the emergence of particular color patterns arises from spatial differences in pigment cell properties and arrangements.
To understand how color patterns are formed by the concerted action of pigment cells in the skin, we use state-of-the-methodologies to analyze cellular differences (single-cell RNA-sequencing) and the three-dimensional arrangement of pigment skills (fluorescence microscopy and 3-dimensional electron microscopy).
Cichlids are also ideal for monitoring the development of pigmentation phenotypes, which constitutes a further approach that we take advantage of. The development and formation of pigmentation phenotype can be followed over days and weeks and development — an analysis that is particularly powerful when different species that vary in their adult patterns are investigated.
Relevant publications
Our research is carried out at the Institute of Biotechnology (BI), HiLIFE, University of Helsinki (UH). BI is a research institute with the mission to carry out high-quality research. BI is one of the most international research units in Finland and is organized into three research programs: Genomics & Evolutionary Biology, Cell & Tissue dynamics, and Structural & Quantitative Biology. The number of PIs working on connected topics (Evo-Devo questions, biology of epithelia, behavioral biology, genomic basis of traits) and methodologies (genome and transcriptome sequencing, tissue analysis, imaging, behavioral experiments) creates a critical mass necessary for high quality genomic, evolutionary, and cell biological research. GEB and CTD programs have well-equipped laboratories with state-of-the-art instruments. The BI hosts several core facilities including histology unit, genomics & sequencing, electron and light microscopy units, and expert personnel. We have a fully equipped laboratory, microscopes, a microinjection workstation, and an established state-of-the-art tropical fish facility.