Transcript Evolution of beak size and shape

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
Beak Components
Frontonasal mass
Maxillary prominences
Lateral nasal prominences
Mandibular prominences
Beak Morphology
• Beak length, width, and depth
– Environmental
• Parental Diet
• Food Availability
– Developmental Genes
• BMP4 and Calmodulin
Environmental Influence
• 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
• 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
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
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.
Questions?