A New Look at the Major
Features of Evolution
Stevan J. Arnold
Department 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)
Lineage mean
A single lineage
Time (generations)
Uyeda et al. 2011
The model that best fits the data
A
has two modes: phyletic & quantum
B
Divergence
White noise
distribution
(dashed)
Burst size
distribution
(solid)
Burst timing distribution
(mean time between
bursts = 25 my)
Uyeda et al. 2011
Probability
Probability
C
Interval (years)
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.
Acknowledgements
PhD 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