Developmental genomics of brains and behavior: Recent work in the lab capitalizes on striking diversity in brain anatomy and social behaviors across Lake Malawi cichlid species. We endeavor to identify the genes and developmental pathways that control these differences. We have shown how gene expression variation at gastrula stage drives divergence in anterior-posterior and dorsal-ventral brain patterning among rock- vs. sand-dwelling Malawi cichlids, and we have used small-molecule manipulation of signaling pathways to phenocopy rock- vs. sand- neural development. Our studies of the genetic and neural basis of adult social behaviors include analysis of (i) sand-dwelling species that construct pit vs. sand castle bowers and (ii) the genomics of rock- vs. sand- social interaction.
York, R. A., Patil, C., Abdilleh, K., Johnson, Z. V., Conte, M. A., Genner, M. J., … Streelman, J. T. 2018. Behavior-dependent cis regulation reveals genes and pathways associated with bower building in cichlid fishes. Proceedings of the National Academy of Sciences, USA 201810140.
York, R.*, C.K. Patil, C.D. Hulsey, J.T. Streelman* and R. Fernald. 2015. Evolution of bower building in Lake Malawi cichlid fish: phylogeny, morphology and behavior. Frontiers Ecol. Evol. 3:18. *indicates co-corresponding authors.
Sylvester, J.B., C.A. Rich, C. Yi, J.N. Peres, C. Houart and J.T. Streelman. 2013. Competing signals drive telencephalon diversity. Nature Comm. 4:1745.
Sylvester, J.B., C.A. Rich, Y-H.E. Loh, M.J. van Staaden, G.J. Fraser and J.T. Streelman. 2010. Brain diversity evolves via differences in patterning. Proceedings of the National Academy of Sciences, USA 107:9717-9723. PMCID: 2906875.
Developmental patterning and regeneration of dentitions: Malawi cichlids exhibit tremendous diversity in tooth shape, tooth number and tooth patterning (size and spacing of teeth). Moreover, every tooth in the jaw is replaced throughout life, de novo, from dental stem cells. In projects supported by the NIH since 2003, we have shown how dental diversity arises during embryonic development, and how tooth patterning is maintained during adult regeneration. Most recently, we have identified and manipulated oro-dental stem cells, demonstrating long-lasting developmental plasticity between cichlid teeth and taste buds.
An, Z., Sabalic, M., Bloomquist, R. F., Fowler, T. E., Streelman, T., & Sharpe, P. T. 2018. A quiescent cell population replenishes mesenchymal stem cells to drive accelerated growth in mouse incisors. Nature Communications, 9(1), 378.
Bloomquist, R.F., N.F. Parnell, K.A. Phillips, T.E. Fowler, T.Y. Yu, P.T. Sharpe and J.T. Streelman. 2015. Co-evolutionary patterning of teeth and taste buds. Proceedings of the National Academy of Sciences, USA, 112: E5954-62. PMCID: 4640805.
Fraser*, G.J., R.F. Bloomquist* and J.T. Streelman. 2013. Common developmental pathways link tooth shape to regeneration. Dev. Biol. 377: 399-414. *indicates equal contribution. PMCID: 3640738.
Fraser, G.J., R. Cerny, V. Soukup, M. Bronner-Fraser and J.T. Streelman. 2010. The odontode explosion: origin of tooth-like structures in vertebrates. Bioessays 32:808-817. PMCID: 3034446.
Fraser, G.J., C.D. Hulsey, R.F. Bloomquist, K. Uyesugi, N.R. Manley and J.T. Streelman. 2009. An ancient gene network is co-opted for teeth on old and new jaws. PLoS Biology 7(2):e31. PMCID: 2637924.
Genomics of evolutionary radiation: Our lab explores the genome-wide patterns and signatures of rapid evolutionary radiation in African cichlids. The two main messages from this work are that (i) Malawi cichlid species possess incredibly similar genomes and share polymorphism due to periodic hybridization and retention of ancestral variation, and (ii) it is possible to identify the signatures of divergent selection against this background of allele sharing and genomic homogeneity. Subsequent studies of other vertebrate radiations (stickleback, finches) have supported divergent selection on standing genetic variation as a primary force in adaptive evolution.
Brawand, D., C. Wagner, Y.I. Li…(69 authors)…J.T. Streelman*, K. Lindblad-Toh*, O. Seehausen* and F. DiPalma.* 2014. The genomic substrate for adaptive radiation in African cichlid fish. Nature 513:375-381. *indicates co-corresponding authors. PMCID: 4353498.
Loh, Y-H.E., E. Bezault, F.M. Muenzel, R.B. Roberts, M. Barluenga, C.E. Kidd, A.E. Howe, F. Di Palma, K. Lindblad-Toh, J. Hey, O. Seehausen, W. Salzburger, T.D. Kocher and J.T. Streelman. 2013. Origins of shared genetic variation in African cichlids. Mol. Biol. Evol. 30:906-917. PMCID: 3603313.
Loh, Y-H.E., S.V. Yi and J.T. Streelman. 2011. Evolution of microRNAs and the diversification of species. Genome Biol. Evol. 3:55-65. PMCID: 3017390.
Loh, Y-H.E., L. Katz, M.C. Mims, T.D. Kocher, S.V. Yi and J.T. Streelman. 2008. Comparative analysis reveals signatures of differentiation amid genomic polymorphism in Lake Malawi cichlids. Genome Biology 9:R113. PMCID: 2530870.
Genetic mapping of adaptive traits: Streelman’s postdoctoral research, which was funded in part by a fellowship from the Alfred P. Sloan Foundation, focused on approaches to identify the genetic basis of key traits in natural populations, rather than inferring trait history from phylogenies. This work borrowed quantitative trait locus (QTL) genetic mapping methods from laboratory model organisms (e.g., the mouse) and produced some of the first QTL analyses in animals from natural populations. In particular, this work showed that adaptive features of the cichlid jaw and the striking orange-blotch color polymorphism had a simple genetic basis in Lake Malawi cichlids.
Parnell, N.F and J.T. Streelman. 2013. Genetic interactions controlling sex and color establish the potential for sexual conflict in Lake Malawi cichlid fishes. Heredity 110:239-246. PMCID: 3668650
Parnell, N.F., C.D. Hulsey and J.T. Streelman. 2012. The genetic basis of a complex functional system. Evolution 66:3352-3366. PMCID: 3490443.
Albertson, R.C., J.T. Streelman, T.D. Kocher and P.C. Yelick. 2005. Integration and evolution of the cichlid mandible: the molecular basis of alternative feeding strategies. Proceedings of the National Academy of Sciences, USA 102:16287-16292. PMCID: 1283439.
Streelman, J.T., R.C. Albertson and T.D. Kocher. 2003. Genome mapping of the orange blotch colour pattern in cichlid fishes. Molecular Ecology 12:2465-2471.