Genetic Mapping of Stickleback Morphological Variation
Work on stickleback in the Cresko lab has led to the discovery that the developmental genetic basis of parallel bone evolution in these fish largely involves genes of major effect, most likely due to regulatory mutations in developmental genes. Surprisingly, the same genes and alleles have been implicated in populations that have independently evolved similar phenotypes. The Cresko lab is now in the process of understanding how these alleles effect their developmental changes, and how this genotype-to-phenotype mapping is affected by different environmental and population genetic contexts.
Technology Development: High Throughput RAD microarray genotyping
A beautiful aspect of the stickleback system is the globally replicated divergence of numerous phenotypes. Identifying additional loci for these quantitative traits in different populations, and drawing general conlcusions about the interactions of development during stickleback evolution, will require the development of new tools and techniques for examining gene expression on global scales, and examine numerous genetic markers simultaneously. To make this possible, the Cresko and Johnson laboratories have produced the first microarray resouces for stickleback, and are pushing to make expression and simple nucleotide polymorphism (SNP) genotyping arrays available at low cost to the stickleback community.
Developmental Genetic Basis of Highly Modified Phenotypes: Pipefish and Seahorse Evo-Devo
In addition to stickleback work, members of the Cresko lab are examining how the developmental genetics of pipefish and seahorses, sister taxa to stickleback, have changed to produce an amazing array of diversity in dermal bones and head shapes. Other members of the laboratory are examining the developmental genetics of vertebral number variation (from a few dozen up to several hundred) among populations of garter snakes. Studies in both of these taxa will lead to much better understanding the genetics of fundamental developmental processes.
Origins of Phenotypic Complexity: Gene and Genome Duplicatio
Lastly, in collaboration with the Postlethwait laboratory, the Cresko lab is studying the evolution of duplicated genes and genomes, and their relationship to organismal diversity. Half of all vertebrate species are teleost fish, and recent evidence suggest that genomic features, including a whole-genome duplication event at the base of the ray-fin fish, may have played a significant role in the teleost radiation. Work in the Cresko lab examines how the partitioning of ancestral subfunctions between gene copies may affect the lineage-specific diversification of developmental programs. Also, in collaboration with Allan Force and F. Bryan Pickett, members of the Cresko laboratory have develped theory to understand how genetic information arises in developmental genetic networks, and how genome duplication affects the structure of these networks.
