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RESEARCH INTERESTS
Vertebrate genetics, development, and evolution
Genetic basis of adaptive change in natural populations of vertebrates
Evolution and development of vertebrate limb reduction
Evolution of the vertebrate skeleton
PUBLICATIONS
What are the genetic and developmental origins of unique traits in natural populations and species of vertebrates? Both evolutionary and medical biologists are interested in the ways that genotypic changes can influence growth and morphology, yet we know remarkably little about the genetic and developmental mechanisms that generate natural morphological diversity. For example, in most cases of adaptive skeletal evolution, we do not know how many genes are involved, which genes are actually responsible for morphological change, whether alterations to these genes affect coding or regulatory regions, or whether the same genes are involved repeatedly in the evolution of similar traits in different populations and species. To address these topics, we combine genetics, developmental biology, and fieldwork to study morphological evolution in natural populations and species.
Genetic architecture of evolutionary change: Sticklebacks are ideal model organisms for genetic and developmental studies of natural populations because different populations of these fish vary dramatically in skeletal structures, yet fish from throughout the Northern Hemisphere can be readily crossed in the laboratory to generate large numbers of progeny. Using an integrative approach that combined genome-wide linkage mapping, quantitative trait loci (QTL) analysis, comparative sequencing analysis, and in situ gene expression studies, we determined that cis-acting regulatory changes in the Pitx1 locus are responsible for limb loss in a pelvic-reduced population of threespine sticklebacks. Remarkably, similar genetic changes appear to control pelvic reduction in ninespine sticklebacks, a different genus of fish that last shared a common ancestor with threespine fish over 10 million years ago.
One of our principal long-term goals is to develop a general understanding of the molecular mechanisms that underlie major evolutionary changes in vertebrate morphology. Toward this goal, we are using the ninespine stickleback for further genetic and developmental studies of natural diversity. Ninespine sticklebacks show interpopulational variation in many skeletal, behavioral, and physiological traits, including some (like pelvic reduction) that also occur in threespine sticklebacks. By comparing genetic results from the two different types of fish, we can critically test whether similar mechanisms repeatedly produce similar traits in divergent but closely related genera, a topic of enduring interest to geneticists and evolutionary biologists.
Broader implications: Many aspects of development are highly conserved among vertebrates. Thus, new insights gleaned from our work will illuminate the genetic mechanisms that control tissue growth, morphology, and functional traits in many other organisms, including both normal and abnormal development in human populations. Ultimately, we hope that our studies of natural variation will inform our understanding of the genetic bases of both adaptive evolutionary change and human disease..
Selected References
M.D. Shapiro (corresponding author), B.R. Summers, S. Balabhadra, A.L. Miller, C. Cunningham, J.T. Aldenhoven, M.A. Bell, D.M. Kingsley. (2009) The genetic architecture of skeletal convergence and sex determination in ninespine sticklebacks. Current Biology 19: 1140-1145.
J.A. Ross, J.R. Urton, J. Boland, M.D. Shapiro, C.L. Peichel. (2009) Turnover of sex chromosomes in the stickleback fishes (Gasterosteidae). PLoS Genetics 5: e1000391.
M.D. Shapiro, M.A. Bell, and D.M. Kingsley. (2006) Parallel genetic origins of pelvic reduction in vertebrates. Proceedings of the National Academy of Sciences of the USA 103:13753-13758.
M.D. Shapiro, N.H. Shubin, and J.P. Downs. (2006) Limb reduction and diversity in reptilian evolution. In B.K. Hall (ed.), Fins and Limbs: Evolution, Development, and Transformation, University of Chicago Press.
M.D. Shapiro, M.E. Marks, C.L. Peichel, B.K. Blackman, K.S. Nereng, B. Jonsson, D. Schluter, and D.M. Kingsley. (2004) Genetic and developmental basis of evolutionary pelvic reduction in threespine sticklebacks. Nature 428: 717-723.
P.F. Colosimo, C.L. Peichel, K. Nereng, B.K. Blackman, M.D. Shapiro, D. Schluter, D.M. Kingsley. (2004) The genetic architecture of parallel armor plate reduction in threespine sticklebacks. Public Library of Science - Biology 2(5): 635-641.
M.D. Shapiro, J. Hanken, and N. Rosenthal. (2003) Developmental basis of evolutionary digit loss in the Australian lizard Hemiergis. Journal of Experimental Zoology 297B(1): 48-56. (Cover article)
M.D. Shapiro, H. You, N.H. Shubin, Z. Luo, and J.P. Downs. (2003) A large ornithomimid pes from the Lower Cretaceous of the Mazongshan Area, Northern Gansu Province, China. Journal of Vertebrate Paleontology 23(3): 695-698.
M.D. Shapiro. (2002) Developmental morphology of limb reduction in Hemiergis (Squamata: Scincidae): chondrogenesis, osteogenesis, and heterochrony. Journal of Morphology 254(3): 211-231. (Cover article)
M.D. Shapiro and T.F. Carl. (2001) Novel features of tetrapod limb development in two non-traditional model species: a skink and a direct-developing frog, pp. 337-361. In M. Zelditch (ed.), Beyond Heterochrony: The Evolution of Development. New York: Wiley-Liss. (Cover photo)
J. Xavier-Neto, M.D. Shapiro, L. Houghton, and N. Rosenthal. (2000) Sequential programs of retinoic acid synthesis in the myocardial and epicardial layers of the developing avian heart. Developmental Biology 219(1): 129-141.
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