Fitness: the relative contribution to the gene pool in the next generation
Species Interactions Change in Fitness as a Result of the Interaction + net gain of fitness 0 no net change of fitness - net loss of fitness Fitness: the relative contribution to the gene pool in the next generation
Species Interactions Species ASpecies B - - - + 0 0 + + Competition Predation Neutralism Mutualism Change in Fitness as a Result of the Interaction + net gain of fitness 0 no net change of fitness - net loss of fitness Fitness: the relative contribution to the gene pool in the next generation
Competition - / - Experiments by Russian ecologist Gause in 1934 examined two closely related species of protozoans. When cultured on a constant food source separately, both reached carrying capacity. When cultured together, P. aurelia proved to be a better competator and drove P. caudatum to extinction.
Two possible outcomes to competition: Competitive exclusion = extinction Niche partitioning = coexistence
Competition - / - Two possible outcomes to competition: 1.Competitive exclusion = extinction (one species dominates) 2. Niche partitioning = coexistence (species have slightly different niches) Therefore, many species may coexist and still use similar resources in a similar way, if they can specialize in their ecosystem.
It is important to remember that this is not the absence of interaction.
Neutralism 0 / 0 Where neutralism becomes more important is when examining larger numbers of species interactions in a bounded community. Example: Tide pool communities. Though their members interact frequently, many neither benefit nor cost one another. Studies suggest that 5% or less show significant correlations in abundance, for example.
Interactions in a tropical ecosystem Eciton burchelli
What types of interactions are present in the army ant situation? Write them in your notebook and explain your thinking.
Now it is your turn to form analogies. In your notebook, come up with analogies for ecological community interactions using your own neighborhood community or school. Explain and draw a quick picture illustrating competition, predation, neutralism and mutualism.