Sockeye salmon natural selection against large bodies. Populations with higher levels of predation tend to evolve smaller body size. Without the threat of predation, salmon that breed early in the season live longer than those that breed late in the season. Other ecological factors like stranding effect select for smaller body size in sockeye salmon when present in a habitat. Stranding is when salmon swim into dry land or shallow water during their migration for spawning and die from suffocation. In fact, studies show that the Sockeye salmon with the largest bodies are most susceptible to stranding mortality. Reproduction is marked by
The purpose of a system is what it does be balanced by a more straightforwardly descriptive view. The term is used in many fields including biology and management. The purpose of a system is what it does The purpose of a system is what it does (POSIWID) is a systems thinking heuristic coined by Stafford Beer. Stafford Beer coined the term POSIWID and used it many times in public addresses. In his address to the University of Valladolid, Spain, in October 2001, he said "According to the cybernetician, the purpose of a system is what it does. This is a basic dictum. It stands for bald fact, which makes