a new look at the major features of evolution stevan j. arnold department of integrative biology...
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A New Look at the Major Features of Evolution
Stevan J. ArnoldDepartment of Integrative Biology
Oregon State University
Outline
• Criteria for the conservation of individual species
• G. L. Simpson’s modes of evolution• Evolution of body size: data• Evolution of body size: models• The concept of quantum evolution• The concept illustrated with African birds• A new criterion for the conservation
Criteria for conservation
• Threatened status• Ecological importance (e.g., keystone species)• Useful to humans• Charisma (e.g., flagship species)• Uniqueness (e.g., aardvark)
Simpson’s two evolutionary modes: phyletic evolution and quantum evolution
Simpson 1944
Simpson’s concept of quantum evolution
Simpson 1944
Modern version of quantum evolution
Lande 1976
Uyeda et al. 2011
Uyeda et al. 2011
Uyeda et al. 2011
±65% change in body size
Uyeda et al. 2011
“The Blunderbuss Pattern”
Uyeda et al. 2011
The multiple-burst model: a process that produces quantum evolution
(peak movement, evolution of the lineage mean)
Uyeda et al. 2011
A single lineage
Time (generations)
Line
age
mea
n
Burst timing distribution (mean time between
bursts = 25 my)
White noise distribution
(dashed)
Burst sizedistribution
(solid)Probability
Prob
abili
ty
Div
erge
nce
B
C
A
Interval (years)
The model that best fits the datahas two modes: phyletic & quantum
Uyeda et al. 2011
Can we detect quantum evolution in the birds of Central Africa?
Provisos• Phylogeny ignored• Exclusive focus on body size• Measure of body size includes tail• Focus on Central Africa ignores
relatives elsewhere
No quantum evolution
Quantum evolution of Great Blue Turaco
Quantum evolution of ground hornbills
Quantum evolution of the Giant Kingfisher
Criteria for conservation
• Threatened status• Ecological importance (e.g., keystone species)• Useful to humans• Charisma (e.g., flagship species)• Uniqueness (e.g., aardvark)• Replacement time (e.g., 25 million years ≧
for a ground hornbill)
Conclusions
• To account for evolutionary pattern in a large data set we need a model with two modes: phyletic and quantum.
• Quantum evolutionary events can lead to rapid, substantial evolution but they are rare, with an average waiting time of 25 million years.
• Some families of birds in Central Africa appear to have experienced quantum evolution (e.g., hornbills, kingfishers, and turacos).
References
Simpson, G. L. 1944. Tempo and Mode in Evolution. Columbia Univ. Press.
Simpson, G. L. 1954. The Major Features of Evolution. Columbia Univ. Press.
Lande, R. 1976.Uyeda, J., T. Hansen, S. J. Arnold, J. Pienaar. 2011. The million-year
wait for evolutionary bursts. Proceedings of the National Academy of Science. U.S.A.
Arnold, S. J. 2014. Phenotypic evolution, the ongoing synthesis. American Naturlist
Van Perlo, Ber. 2002. Birds of Western and Central Africa. Princeton Univ. Press.
AcknowledgementsPhD advisor: Arnold Kluge
Research collaborators: Suzanne Estes, Josef Uyeda, Thomas Hansen, Jason Pienaar
Data: Phil Gingerich, Andrew Hendry, Michael Kinnison NSF OPUS program: Mark Courtney