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The evolution of beak size and shape in Darwin’s Finches. The role of Developmental Genes and Environmental Conditions. Lindsey Williams Elisabet Minter Corita Fields. Smithsonian: Osteology Hall. Smithsonian: Osteology Hall. Smithsonian: Osteology Hall. Examples of Beak Morphology. - PowerPoint PPT Presentation
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The evolution of beak size and shape in Darwin’s Finches
The role of Developmental Genes and Environmental Conditions
Lindsey WilliamsElisabet Minter
Corita Fields
Smithsonian: Osteology Hall
Smithsonian: Osteology Hall
Examples of
Beak Morphology
Smithsonian: Osteology Hall
Beak Components
Frontonasal massMaxillary prominences
Lateral nasal prominences
Mandibular prominences
Beak Morphology
• Beak length, width, and depth– Environmental
• Parental Diet• Food Availability
– Developmental Genes• BMP4 and Calmodulin
• Parental Diet• Food Availability– Small beaked finches prefer small seeds– Large beaked finches prefer large seeds but have
the ability to consume small seeds
Environmental Influence
Environmental Influence
• During drought of 1977– soft seeds less abundant– Tribulus seeds more abundant• Large, difficult to open
• Larger beaked finches were more fit than their smaller beaked counterparts
• Larger beaks survived due to their ability to open Tribulus seeds easier.
Genetic Influence
• Bone morphogenic protein 4 (BMP4)
• Calmodulin (CaM)
BMP4 Expression
• Examined BMP4 Expression in distal beak mesenchyme of finches
Figure . A. Beak morphologies. B. Stage 26 BMP4 expression C. Stage 29 BMP4 expression
• Result– Enhanced cell proliferation – larger beaks due to significant increases in width,
and depth• Conclusion– Darwin’s finches exhibit different beak
morphologies in part due to the expression of BMP4
BMP4 Expression
Calmodulin Expression
• Embryonic Stage – Injected CaM via a RCAS
virus into embryo at stage 24
– Collected specimens at day 10
• Result and Conclusion Figure . A shows the wild type specimen without additional presence of calmodulin. B shows the RCAS:CaM infected specimen.
Calmodulin Expression
• Examined expression and calmodulin in the skull of embryonic finches
• Conclusion
Figure . A. and B. Morphologies from a monophyletic group. C. Skeletal morphological differences. D. CaM expression in distal –ventral domain in the mesenchyme of the upper beak.
BMP4 and CaM Expression
Conclusion and Further Research
• Beak morphology is influenced by both developmental genes and environmental factors, not just one
• Expression of CaM and BMP4 in other anatomical structures in both birds and mammals
• What protein is expressed that increases beak length once CaM is expressed?
Bibliography
• Abbott, Ian, L. K. Abbott, and P. R. Grant. "Seed Selection and Handling Ability of Four Species of Darwin's Finches." The Condor 7.3 (1975): 332-35.
• Abzhanov, Arhat, Winston P. Kuo, Christine Hartmann, B. Rosemary Grant, Peter R. Grant, and Clifford J. Tabin. "The Calmodulin Pathway and Evolution of Elongated Beak Morphology in Darwin's Finches." Nature 442.7102 (2006): 563-67. Print.
• Abzhanov, Arhat, Meredith Protas, B. Rosemary Grant, Peter R. Grant and Clifford J. Tabin. “Bmp4 and Morphological Variation of Beaks in Darwin's Finches.” Science 305.5689 (2004): 1462-465.
• Freeman, Scott, and Jon C. Herron. Evolutionary Analysis. 4th ed. Upper Saddle River, NJ: Pearson Prentice Hall, 2007. Print
• Grant, Rosemary B. and Peter R. Grant. “High Survival of Darwin's Finch Hybrids: Effects of Beak Morphology and Diets.” Ecology 77. 2 (1996): 500-509.
• Herrel, A., J. Podos, S. K. Huber, and A. P. Hendry. "Bite Performance and Morphology in a Population of Darwin's Finches: Implications for the Evolution of Beak Shape." Functional Ecology 19.1 (2005): 43-48.
• Snodgrass, Robert E. "The Relation of the Food to the Size and Shape of the Bill in the Galapagos Genus Geospiza." The Auk 19.4 (1902): 367-81. JSTOR. Web. 19 Apr. 2011. <http://www.jstor.org/stable/4069598 .>.
• Wu, Ping, Ting-Xin Jiang, Sanong Suksaweang, Randall Bruce Widelitz, and Cheng-Ming Chuong. "Molecular Shaping of the Beak." Science 305.5689 (2004): 1465-466.
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