the science of ecology and the Gaia hypothesis

Ecology is the science that studies organisms and their relationships with each other and the environment.  Ecology is a very broad science that encompasses a lot of topics because the Earth has a lot of species and a lot of environments, and is considered by some (Lovelock, James 2007) to be one big interconnected ecosystem, rather than many isolated ones.  Some even consider the Earth to be a single organism made up of many interconnect parts, that tries to maintain homeostasis.  I'm fond of this theory, called the Gaia hypothesis, because I believe that ecosystems are always connected to and affected by other ecosystems.  The evidence for the theory that the Earth is one single organism stems from three pieces of evidence for the fact that the Earth somehow maintains homeostasis: by keeping atmospheric content, ocean salinity, and global temperatures relatively constant despite changing inputs.  One of the reasons that I think this theory has merit is that homeostasis seems to be a common theme to both organisms and natural environments, so why not the whole Earth?  Feedback responses (both positive and negative) are observed to be activated in organisms and natural environments when conditions vary too much from the set point of a particular parameter.  I also likes this theory because it expands on Charles Darwin's theory of evolution by adding the idea of the evolution of natural environments.  In other words, the Earth, as a single organism maintaining homeostasis around set points that can change with time, selects for environments which help it to do that, and these environments select for the species that occupy them.