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Discussion 2 - Abzhanov2004

Discussion 2 - Abzhanov2004 - REPORTS 19 Materials and...

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19. Materials and methods are available as supporting material on Science Online. 20. J. N. Reeve, J. Nolling, R. M. Morgan, D. R. Smith, J. Bacteriol. 179 , 5975 (1997). 21. R. K. Thauer, Microbiology 144 , 2377 (1998). 22. S. J. Hallam et al ., data not shown. 23. S. Angelaccio et al ., J. Biol. Chem. 278 , 41789 (2003). 24. L. Chistoserdova et al ., Microbiology 146 , 233 (2000). 25. C. J. Marx, J. A. Miller, L. Chistoserdova, M. E. Lid- strom, J. Bacteriol. 186 , 2173 (2004). 26. C. H. Kuhner, B. D. Lindenbach, R. S. Wolfe, J. Bacte- riol. 175 , 3195 (1993). 27. Special thanks to L. Christianson, P. Girguis, and V. Orphan at MBARI for technical assistance, and the pilots of the ROV Tiburon and the captain and crew of the R/V Western Flyer. We also thank S. Pitluck and the Joint Genome Institute staff for technical assistance, and W. Ussler and D. Graham, who provided insight and commentary. This study was supported by the David and Lucille Packard Foun- dation, NSF grant MCB-0236541, and the U.S. De- partment of Energy’s Office of Science, Biological and Environmental Research Program, and the Uni- versity of California, Lawrence Livermore National Laboratory, under contract W-7405-ENG-48, Law- rence Berkeley National Laboratory contract DE- AC03-765F00098, and Los Alamos National Labo- ratory contract W-7405-ENG-36. Sequences have been submitted to GenBank under accession num- bers AY714814 to AY714873. Additional data are available at www.jgi.doe.gov/aom. Supporting Online Material www.science.org/cgi/content/full/305/5689/1457/ DC1 Materials and Methods Figs. S1 to S3 Tables S1 and S2 References and Notes 6 May 2004; accepted 23 July 2004 Bmp4 and Morphological Variation of Beaks in Darwin’s Finches Arhat Abzhanov, 1 Meredith Protas, 1 B. Rosemary Grant, 2 Peter R. Grant, 2 Clifford J. Tabin 1 * Darwin’s finches are a classic example of species diversification by natural selection. Their impressive variation in beak morphology is associated with the exploitation of a variety of ecological niches, but its developmental basis is unknown. We performed a comparative analysis of expression patterns of various growth factors in species com- prising the genus Geospiza. We found that expression of Bmp4 in the mesenchyme of the upper beaks strongly correlated with deep and broad beak morphology. When misexpressed in chicken embryos, Bmp4 caused morphological transformations par- alleling the beak morphology of the large ground finch G. magnirostris . Darwin’s finches are a group of 14 closely related songbird species on the Gala ´pagos Is- lands and Cocos Island ( 1 3 ) collected by Charles Darwin and other members of the Beagle expedition in 1835 ( 4 ). Many biology textbooks use these birds to illustrate the history of evolutionary theory as well as adaptative radiation, natural selection, and niche partition- ing ( 5 7 ). The diverse shapes and sizes of the finch beaks are believed to be maximally effec- tive for exploiting particular types of food, including seeds, insects, and cactus flowers ( 3 , 7 ). The external differences in beak morpholo- gy reflect differences in their respective cranio- facial skeletons ( 3 , 8 ). The specialized beak shapes are apparent at hatching ( 3 , 8 ) and thus are genetically determined.
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