Many organisms have relationships that are not understood until it is too late. Dodo Bird Calvaria tree
The dodo bird and the calvaria tree is an example of how one species interacts with another species. Ecology is the study of relationships among organisms and between organisms and their environment.
The dodo bird and the calvaria tree are living in the part of the Earth called the biosphere. The biosphere is the part of the Earth that supports living organisms.
Abiotic Factors in the Biosphere All organisms depend on the environment around them. Water, soil, sunlight, temperature, and air are all abiotic factors. Abiotic factors are the non-living things of the environment. a = not biotic = living
Abiotic Factors in the Biosphere The abiotic factors in an area determine what organisms are able to live in that environment. Remember natural selection? Desert fox Arctic fox
Biotic Factors in the Biosphere Abiotic factors do not provide everything an organism needs to live. All organisms also depend on other organisms for food, shelter, protection, or reproduction. Living organisms in the environment are called biotic factors.
Biotic Factors in the Biosphere Examples of biotic factors helping organisms to live: Mushrooms would not be able to grow without the decaying bodies of other organisms to feed on. Bees could not live without pollen from flowers.
Ecosystem Community Population Levels of Biological Organization You have already learned that the living world is highly organized (classification unit). The biotic and abiotic factors are organized, too.
Populations Individual organisms of the same species that live in the same place and can produce young form a population.
Populations Members of populations compete for food, water, mates, and space. The resources of the environment and how the organisms use these resources determine how large a population can be.
Communities Groups of populations that interact with each other in an area form a community. Populations in a community depend on each other for food, shelter, or for other needs.
Ecosystems An ecosystem is made up of a biotic community and the abiotic factors that affect it. Ecosystem = biotic factors + abiotic factors
Characteristics of Populations Population Density: the size of a population in an area of a specific size Example: If there are 100 mice in an area of a square kilometer, the population density is 100 mice per km2.
Characteristics of Populations 2. Limiting Factors: Any biotic or abiotic factor that restricts (limits) the number of individuals in a population. Examples of limiting factors: amount of food, water, living space, mates, and nesting sites.
Characteristics of Populations 3. Carrying Capacity: The largest number of individuals an environment can support and maintain for a long period of time.
Characteristics of Populations If a population becomes bigger than the environment’s carrying capacity, some individuals will not have enough resources.
Interactions in Communities Populations are regulated not only by the supply of food, water, and sunlight, but also by the actions of other populations.
Interactions in Communities The most obvious way one population can limit another is by predation. Predation is when one organism eats another organism.
Interactions in Communities Predators are more likely to kill old, sick, or very young prey (organisms that get hunted and eaten). This helps keep the population of prey healthy and strong. “Survival of the Fittest”
Interactions in Communities Many species of organisms have close, complex relationships with each other for survival. Symbiosis is any close relationship between two (2) or more different species
Interactions in Communities Mutualism: a symbiotic relationship that benefits (helps) both species
Interactions in Communities Commensalism: a symbiotic relationship that benefits (helps) one partner but does not help or hurt the other partner.
Interactions in Communities Parasitism: a symbiotic relationship that helps the parasite and hurts the parasite’s partner, or host.
Habitats and Niches In a community, every species has a job. Each also has a certain place it lives. Where an organism lives is called its habitat. The job an organism has is called its niche.
Habitats and Niches What a species eats, how it gets its food, and how it interacts with other organisms are all parts of its niche.
Energy moves through an ecosystem in the form of food. Producers are organisms that capture energy from the sun and use it for photosynthesis.
Consumers are organisms that get their energy when they eat producers or other organisms.
Decomposers are organisms that get their energy from breaking down the bodies of dead organisms.
Food Chains A food chain is a simple way of showing how energy from food passes from one organism to another.
Food Webs There are many food chains in any ecosystem. A food web is a series of overlapping food chains.
Ecological Pyramids Energy is lost as it travels up a food chain. Only a small part of the energy that comes from the sun is captured by plants to make food.
Ecological Pyramids When an herbivore (an animal that eats only plants) eats a plant, some of the energy in the plant is transferred to the herbivore, but most is given off into the atmosphere as heat.
Ecological Pyramids The same thing happens when a carnivore eats an herbivore.
Energy Pyramid The energy pyramid shows how energy is lost as it goes up the food chain.
The Cycles of Matter Matter on Earth is never lost or gained, but used over and over again. In other words, it is recycled. The carbon atoms in your body right now have been on Earth since the planet was formed billions of years ago.
The Cycles of Matter Many important materials that make up your body cycle through ecosystems. These materials include: Water Carbon Nitrogen
Ecological Succession Ecological succession is the process of gradual change from one community of organisms to another.
Primary Succession Primary succession is ecological succession that begins in a place that does not have soil.
Primary Succession The first community of organisms to move into a new environment is called the pioneer community. These are usually organisms that can survive in bad conditions.
Primary Succession Pioneer communities change the conditions in their environment to make it better for other organisms to start living there. These new organisms gradually take over.
Secondary Succession Secondary succession is succession that begins in a place that already has soil and was once the home of living organisms.
Climax Communities A climax community is a community that has reached the final stage of ecological succession.
Climax Communities As succession happens, the abiotic and biotic factors change. The amount of sunlight, nutrients, and water changes as new species grow. In a climax community, the abiotic and biotic factors stay the same unless the trees are cut down or there is a fire.