The evolution of development is central to questions of how old forms are modified and how apparent novelties originate. The Cresko Lab investigates the genetic basis of phenotypic evolution over shallow and deep time scales. Stickleback populations have diversified in phenotype, sometimes over very short periods (in a matter of decades). Some of the most striking of these morphological differences can be seen in comparing freshwater and marine fish, whose skeletons may differ in size, shape and the number and robustness elements. Rich variation is seen in populations where these ecotypes have interbred. Lab members are interested in tracing morphological differences in cranial bones, for example, to regions of the genome using morphometric analysis and GWAS in natural populations that vary in skeletal traits, followed by candidate gene analysis using in situ hybridization to look at gene expression during development and alteration of gene function using CRISPR. On a much deeper evolutionary time scale, we are investigating the evolution of novel morphology in the syngnathid fish, which have a derived and specialized head shape for “pipette” suction feeding, an elongated body encased in dermal armor, loss of pelvic fins, and gain (in males) of specialized, placenta-like structures for brooding embryos. We are building genomic resources (an annotated genome assembly, with an integrated genetic map, using short-read sequencing of genomic DNA and transcripts) for the study of these specializations and other evolutionary aspects of Syngnathus scovelli, the gulf pipefish.