Genomics and vertebrate adaptive radiation: A celebration of the first cichlid genome

Abstract

The symposium ‘‘Genomics and Vertebrate Adaptive Radiation: A Celebration of the First Cichlid Genome’’ was held at the annual meeting for the Society of Integrative and Comparative Biology in Boston in January, 2009. While the central topic was the genomics of adaptive radiation in cichlid fishes, the symposium integrated speakers studying genotype-to-phenotype maps in other model organisms. Genomic studies investigating cichlid phenotypes were paralleled with studies using similar techniques to answer questions in other adaptive radiations. The topics were not restricted to any one research area in order to foster interdisciplinary discussions from developmental, physiological, and behavioral research with the common goal to apply and enhance genome-level analyses. Research programs such as the genetics and development of craniofacial diversity, behavior, and color patterns in zebrafish, mouse, and stickleback were described and then augmented with speakers focusing on the genetic and developmental architecture of cichlids’ jaws, behavior, and color. This integration across both established model systems and the new cichlid model sought to capitalize upon a comparative organismal framework that focused on how linking genomic information to studies of phenotype could hasten scientific discovery. The comparative and integrative approach inherent in most cichlid research extends to the current genome sequencing effort. Multiple cichlids have been chosen for genome sequencing because of their important applied as well as scientific value. The genomes of the cichlid fish Tilapia nilotica and as many as three other species representing the faunas of the largest East African Rift lakes will be sequenced. Astatotilapia burtoni could represent the 400 species present within Lake Tanganyika and its surrounding rivers because it is a genomic model for social regulation of behavior (Renn et al. 2008). Paralabidochromis chilotes could provide a representative for the !350 species from Lake Victoria, a radiation being strongly affected by ecological change (Seehausen et al. 2008). Metriaclima zebra could also be sequenced because it has been used to build a haplochromine linkage map (Albertson et al. 2005) and is a member of the !500–1000 species in the very recent radiation from Lake Malawi. These three other cichlid species, representing independent radiations within the East African Rift Lakes, span the incredible craniofacial, color, and behavioral diversity of the nearly 2000 species that inhabit this region (Salzburger 2008). Tilapia nilotica will be the first cichlid genome completed, and it is not only a major source of protein for much of the world but also is a focal organism for comparative renal physiology, ion balance, and endocrinology (Rengmark et al. 2007; Inokuchi et al. 2009). The sequencing of these cichlid genomes will provide an unprecedented view simultaneously into the genetics of one of the world’s major protein sources and into the unequalled phenotypic diversity of these fishes. In the symposium, researchers studying cichlids and other model vertebrate organisms focused on exploring the ways in which genomic studies can inform our mechanistic understanding of adaptive phenotypic diversity. The repeated phenotypic convergence in cichlid fishes makes this diverse vertebrate group exceptional for comparative analyses of genetics and development. Dr Darrin Hulsey described how cichlids are an ideal group to examine the similarities and differences in genomic and developmental changes that have lead to repeated convergence in neuralcrest-derived attributes as diverse as jaws, color,