[MUSIC] Hi learners. Welcome to the 11th lecture of my course, Ecology From Cells to Gaia. Today we will talk about fundamental ecological processes. We can classify ecological entities in an interactical manner. From genes to individuals, populations, species, communities, ecosystems and finally, to the biosphere. The basic question to develop a planetolary ecology is for any planet with carbon based life, which persists over geological time scales, what is the fundamental set of ecological processes that must be present? In 2001, Norman Peace has outlined a number of reasons for thinking that any life in the universe will be based on organic chemistry. One of the most widely discussed possibility about the origin of life is the colonization or recolonization of the Earth from Mars via microbes transported in meteorites originating from planetary surfaces. An interesting variation of this idea is that during a large asteroid impact on Earth, microorganisms could be ejected into the space inside rocks which later fall back onto the new sterile Earth, so reseeding our planet. Any process which tends to increase the survival of life on a planet is said to have a positive Gaian effect, while one that decreases the chances of survival has a negative Gaian effect at this base. Gaia theroy, proposed by James Lovelock and co-developed by the microbiologist Lee Margulis in 1970s suggests that organisms interact with their inorganic surroundings on earth to form a symbiotic self regulating complex system that helps to maintain and perpetuate the condition for life on the planet. This theory explains how the biosphere and evolution of life beings influence the stability of all salinity, global temperature, oxygen in the atmosphere, a liquid hydropshere and other environmental conditions that affect the habitability of Earth. The second law of thermodynamics states that heat flows from a hotter to a colder body so that entropy is greater, or at least not lower, after any given process has taken place. In 1995, Margulis and Sargon described organisms as island of water in an ocean of cows. To survive, all organisms must acquire energy from their environment. In so doing, produce waste products which they release back into their surroundings. Indeed, this is so fundamental that it could be considered the basic concept of ecology. Lanton, in 2004, described Gaia as a type of planetary scale open thermodynamic system with abundant life supported by a flux of free energy from a nearby star. If transport on some planets may be organized to produce entropy at the maximum possible rate. The universal requirement for increased entropy from the second law of thermodynamics is responsible for the general circulation of the atmosphere on Earth, and other similar planets. So organisms maintain their highly ordered state by taking in free energy from the environment, and as usual, these energies cannot be 100% efficient, releasing waste product back into the environment. So planetary ecology can work because of diversity. As Tyler in 1998, has written, a monocultural planet is, therefore, a thought experiment with no place in reality. In any successful ecological system, it is necessary for material and waste products to be recycled to make them available for use. Any ecological system that produced an product which couldn't be broken down would, on the geological time scale, be in trouble. I provide you an example of recycling. White-rot fungi, break down both lignin and cellulose. Their food source is the cellulose only. However, they need to break down the lignin enzymatically to get it. Consuming organ is not evolved, this could have proved problematic for abundant life on Earth. With increasing amounts of resources and organic deposit and unavailable to life. So one species waste product can be a resource for another species. An ecological system needs organisms from at least two major guilds, autotroph and decomposers, which really is a material from waste products, including dead autotrophs. As such, any ecological system, which has survived for a geological period of time on a planet, must consist of at least two types of organism. So at the end of this lesson, I have a question for you. What is the importance of other major guilds, such as predators and parasites, in the equilibrium of ecological system in a Gaian perspective? Try to formulate an answer, and we will analyze this process in the next lesson. See you next time, bye. [MUSIC]