Fig. 6

The ecologic structure of turnover pulses. a Reduction of an abundant, widespread species (a metapopulation consisting of sources and sink populations, 1–5) to a few isolated remnants (6–8)—a situation likely to promote a bout of allopatric speciation (if the population remnants are not too small). b Simultaneous collapse of numerous local ecosystems (1) that were connected in various ways (2) to produce a regional network, resulting in a few disconnected remnants (3). c Turnover in terms of changes in relative abundance of the resident organisms (a–j), with some rare species becoming abundant (1), prominent species reduced in abundance (2), and reduction or complete elimination of other species (3)