Ideas on Development, Evolution and Community Assembly: For Discussion
Dr. Stuart Kauffman
University of Vermont, Complex Systems Center
September 16, 2010
107 Jeffords Hall
Light refreshments will be served beginning at 3:30 pm in 110 Jeffords.
C.H. Waddington, famous mid-20th-century developmental and evolutionary biologist, developped the metaphor of an epigenetic landscape with the zygote at the top of a hill, with daughter cells rolling downhill into branching valleys corresponding to cell differentiation lineages. Models of large genetic regulatory networks confirm "Wad's" intuition and lead to renewed understanding of differentiation, cancer, and evolution. In addition, old puzzling results of Stuart Pimm and Mac Post showing that model econlogical communities have the property that as new species are added, at random, to an ecosystem with abundant energy, at first adding species is easy, then becomes progressively harder. This phenomenon MAY be related to the famous KSat phase transition, which I will discuss for our joint discussion.
A further potential development of the KSat framework is that MULTIPLE solutions to the KSat problem may exist, each corresponding to one vertex on an N dimesnional community Boolean hypercube representing which species are present or absent. Each such solution is a simplified "community" whose species, if present, can co-exist. Then the vertices that are solutions may be 1 move Hamming neighbors on the hypercute, allowing community construction and evolution via one species additions or deletions from the community. These "permissible" communities may form connected, percolating walks in communit composition space, hence allow rapid evolution of community structure. In contrast, permissiable communities of species that can co-exist may form isolated islands of vertices, or isolated community vertices. From this we may be able to derive numerical results that addition of an extra species may induce avalanches of extinction events whose size distriubtion appears to be a power law.
Dr. Stuart Kauffman, who holds a medical degree (M.D.) from the University of California, San Francisco, is well known for his work on models in various areas of biology, including autocatalytic sets in origin of life research, gene regulatory networks in developmental biology, and fitness landscapes in evolutionary biology. He holds the founding broad biotechnology patents in combinatorial chemistry and applied molecular evolution, and received a MacArthur Fellowship for 1987-1992.
Dr. Kauffman rose to prominence through his association with the Santa Fe Institute (a non-profit research institute dedicated to the study of complex systems), where he was faculty in residence from 1986 to 1997 and where he continues to be an external professor. In January of 2010, he joined the University of Vermont faculty where he is continuing his work with UVM's Complex Systems Center.
For more information about Dr. Kauffman, please see his UVM webpage.