Synthesis: Back to Santa Rosalia, or No Wonder There Are So Many Species
Modern competition research started with G.E. Hutchinson’s, Homage to Santa Rosalia, and his now-famous question “why are there so many species?” (Hutchinson 1959,1961). This confronted observed species richness with the competitive exclusion principle, a
- PDF / 1,459,116 Bytes
- 12 Pages / 439.32 x 666.12 pts Page_size
- 26 Downloads / 190 Views
Modern competition research started with G.E. Hutchinson's, Homage to Santa Rosalia, and his now-famous question "why are there so many species?" (Hutchinson 1959,1961). This confronted observed species richness with the competitive exclusion principle, a principle that had been derived from theory and from highly artificial experiments. It would always have been easy to point at the "artificial" character of the competitive exclusion principle. Indeed many researchers have refused to deal with Hutchinson's question because they considered it a pseudo-problem, which arose from a contradiction between overly simplified theory and complicated reality. However, those who took Hutchinson's challenge seriously have gained fundamental insights into how competition plays out in nature, how species coexist, and how communities function. In this final chapter we attempt to synthesize these insights as they have been presented in this book. We focus on six key topics: • Identification of major trade-off axes (Sect. 8.1) • Confirmation of the "intermediate disturbance hypothesis", and detection of interactions among competition, resource supply, predation and disturbance in field experiments (Sect. 8.2) • The interplay of space colonization, dispersal and neighborhood competition in sessile communities (Sect. 8.3) • Potential for chaotic, self-generated heterogeneity in communities (Sect. 8.4) • Role of exclusive resources in competition among mobile animals (Sect. 8.5) • Coexistence by slow exclusion (Sect. 8.6) In addition to this summary, we attempt to resolve the debate on equilibrium vs. non-equilibrium dynamics (Sect. 8.7) and outline what we consider important research questions for the decade ahead (Sect. 8.8). We call for an investigation into the relative importance of competition in determining local species richness.
Ecological Studies, Vol. 161 U. Sommer, B. Worm (Eds.) Competition and Coexistence
208
U. Sommer and B. Worm
8.1 Trade-Offs All mechanisms of coexistence discussed in this book have a prerequisite which is usually taken for granted in experimental competition research: species have to conform to the principle "a jack in every trade is a master in none", i.e. that there have to be trade-offs in the ability to withstand different selection pressures. For example, the best competitor would usually not be the best in resisting predation, or in colonizing newly opened sites. In this sense, life-history trade-offs form a unifying principle behind species coexistence. The examples provided in this book show that there are obvious trade-offs in competitive abilities for different resources, but that they are not the only trade-offs which facilitate coexistence. Particular trade-offs are: • Trade-off in resource requirements for growth: While all primary producers require essentially the same resources (light, CO2, mineral nutrients, and for land plants also water) there are differences in optimal ratios of resource supply and competitive abilities for the different resources. Now we have good empirical e
Data Loading...
