Mathematical models of genetic regulatory networks or immune networks, or the behavior of the stock market, are typical examples. Any thoughts or suggestions on sources, methods and readings to introduce complexity theory to liberal arts undergrads, esp. There are several good books that are introductions to complexity theory. Two books called Complexity, one by Mitch Waldrop, and the other by Roger Lewin, are both fine introductions to complexity and the Santa Fe Institute. John Holland's book Emergence is another fine book, and my own second book, At Home in the Universe, is also a very readable introduction to many of the topics central to complexity theory.
None is overburdened with equations.
The powerlaw lifetime distribution of species and genera. The powerlaw distribution of species per genus, genera per family, and so on. If the biosphere's normal behavior is self-organized critical, then habitat fragmentation and other human impacts on the global ecosystem may be unleashing a major extinction event. Careful modeling and further scientific work needs to be carried out to explore the self-organized criticality hypothesis. The company that I founded to apply complexity theory to practical business and organizational problems, Bios Group Inc., has been making models of optimal organizational structure to preserve the capacity to adapt.