 hierarchy of ecology, first the contents, ecology, ecological hierarchy, organism, population, community, ecosystem and the biosphere. First the definition of ecology. Ecology is basically a branch of science or a branch of biology which deal with the interaction of organisms with each other and with their physical environment. If we simply talk about ecology, we focus on two things. The living organisms in the environment, how they are interacting with each other, how you are interacting with each other and how they are interacting with their physical environment. The interaction with their physical environment is like this. So we focus on two things, ecological. Studies are ecology. So if we look at ecology, different types of animals are present. Living organisms, plants, microbes, different types of living things are present in the environment. So the environments, they form a specific hierarchical pattern within the ecosystem, the ecological environment. So what is ecological hierarchy? We also call hierarchy as a pattern in which we categorize a specific species. Some animals are at a lower level, then at a higher level, then at a higher level. So when we make different levels in any system, these levels are called hierarchy. So in the ecosystem, the levels of hierarchy are actually helpful in studying different components of ecological environment or ecosystem. To study different components of ecology, the levels of hierarchy are very important. So in ecology, there are five levels of hierarchy. Animals, the living organisms have five levels of hierarchy divided. The first level of hierarchy is the organism level. The second one is the population level. The third one is the community level. The fourth one is the ecosystem level. And the fifth one is the biosphere level. So organism level of hierarchy. In ecology, the first level, the base, the lower group of hierarchy, that is the organism level. So in organism level, we study the single individual. We study one organism because sometimes we say it is the individual level. The organism level is also called the individual level. In the individual level, we see how a single organism plays its role in the environment. How a single organism is interacting with its environment. How does it interact in the environment? A single individual can be human. Even if we have an animal, it may be a bear, it may be a dog, it may be a lion. When we study a single animal, it will be the individual level. The second level in ecological hierarchy is the population level. So population is a group of animals, a group of organisms. When an organism has a group that belongs to the same species, and is living in the same place, what can we say? It is the population. So what will be the definition of the population? Population is a group of organisms belonging to the same species, present at the same area at the same time. When the members of the same species are present at the same place, at the same time, what can we say? That is the population. So at the population level, we see how a population is interacting with its environment. So at the population level, we study how the members of the population they are interacting with each other, how they are living together, and how they are interacting with other members of the ecosystem. The third level in ecological hierarchy is the community level. So normally at one area, many populations are present. So all the populations present at one area, they collectively call the community. Different populations that are present at one place, what will we name them? We will name them as a community. For example, if we talk about an environment, there are deer populations in it. If there are buffaloes, there are wild populations. If there are giraffes, there will be a third population. If there are trees, there will be one type of tree, one type of population, another type of tree, another type of population. Overall, there will be many populations there, and collectively all the populations are called as the community. What we call a community structure. Normally, the different types of populations or species are present, we say it is rich in diversity. So the number of populations in the community will be more. If there is less diversity in it, we will say it is a simple community. So this community is less diversity in it. What do we study in community ecology? You say, what do we study in ecology at the community level? At the community level, we study how the populations that make the community interact with each other. At the population level, we see how the members interact with each other. When it comes to community populations, at the community level, we see how the populations interact with the other populations. The main things that are discussed are the predation. How the lion population affects the deer population. Parasitism. How the worms or insects affect the cattle population. This is how we have competition. The competition is that two different types of populations are using the same resources. They compete with each other. So these are some attributes of the community level, the hierarchy level. The next is the ecosystem level. The ecosystem basically is a system in which the living and non-living things interact with each other. When a community interacts with their physical environment, it will be called an ecosystem. We give it an ecosystem name. In the ecosystem, the living organism is called biotech components, and the non-living organism is called abiotic components. In the ecosystem, we see how the biotech components interact with the abiotic components or the biotech components that interact with each other. Different physical factors like temperature, weather, and other conditions are discussed on this level. The last level of the colloquial hierarchy is the biosphere level. Biosphere is the global ecosystem. That is, wherever life is present on earth, if we collect it, it will become a biosphere. Whether it is present on earth, on oceans, on land, or in the air, microbes are present. When we discuss everything in a combined way, we say it is the biosphere. Biosphere is the part of the earth where life exists. So, what will be the focus on the biosphere level? The focus on the biosphere level is on the large scale. The focus is on geology. The shape of the earth doesn't mean what is its overall pattern. What is the climate? We will study the climate at the biosphere level. From this, water availability, water bodies, where they are present in the biosphere, where they are present, where they are not, where they are not present. Then the latitude. Latitude indicates that, latitude and longitude are 2-devain. Longitude and longitude are not present. Longitude means longitude, longitude means longitude. Longitude is imaginary lines that are dividing it. The environment changes between latitude and longitude. So, we discuss this in a Biosphere level.