Module 9S1 Ecological Interactions

Big Picture

Humans live with other humans. For the most part, our interactions with other species are limited to the family pet, or to food from the grocery store. Organisms in the wild, however, live in complex communities comprised of many species of different trophic levels, interacting daily in positive, negative, and competitive relationships. We have little understanding of the instinctive and learned behaviors that allow organisms to live (and die) together while competing for the same scarce resources. Over the millennia, successful ‘partnerships’ have developed between species. As long as these relationships improve survival, the alleles that govern them will remain in the population. Chemical, physical, and behavioral defenses that improve survival have been selected for in the same way. The species make-up of a community changes over time – not due to evolution, but due to natural successions that see new producer and consumer players filling niches as habitats age and change.

You will explore the following essential questions:

• What are the living relationships that exist between individuals that ensure survival?
• What mechanisms protect individuals in a population from individuals in other populations?
• How can the various populations that make up a community change over time, or remain as a climax community?