Interactions between organisms, ranging from mutual dependencies to host-pathogen and predator-prey interactions, underlie social and ecological systems. Interaction systems are complex. For example, interactions between cells will influence both lower (molecular level) and higher (organismic and social) systems. Moreover systems change over time and will respond to environmental perturbations in various, often unexpected ways. Systems thinking provides an analytical context to consider biological systems at all levels, from the gene to the ecosystem.
- 10.0: Introduction to Social Systems
- At the molecular level it is common to focus on the interactions between proteins and DNA (genes) that control gene expression. These molecular level interactions play an important role in determining how cells behave. Interactions between cells influence the behaviors of the interacting cells, as well as the overall behavior(s) of biological communities and multicellular organisms. Interactions between organisms, ranging from mutual dependencies to host-pathogen and predator-prey interactions,
- 10.1: Microbial Communities
- Some organisms secrete toxins to control the growth of others. Some secrete molecules that influence the behaviors of other organisms (including themselves). There are complex molecular level conversations going on between the organisms within an ecosystem and the cells within an organism. Organisms are not independent, their behaviors are altered by their environment and they in turn, alter their environment.
- 10.2: Making Metazoans
- As we move from quorum sensing between organisms of the same type, we come to what are known as biofilms. These are microbial communities, such as the plaque that forms on your teeth, and consist of a number of different types of often co-dependent organisms. While horizontal gene transfer may occur between these different organisms, they remain distinct and give rise to organisms genetically related to their parent(s).