CHAPTER 2 NOTES: INTERACTIONS OF LIVING THINGS
SECTION 1: EVERYTHING IS CONNECTED
Ecology- the study of the interactions between organisms and their environment.
2 parts to an environment:
- biotic- all of the organisms that live together and interact with one another.
-abiotic- all of the physical factors of the environment. Like the water, soil, light, and temperature. These things affect organisms living in a particular area.
Organization of the Environment
- environments are arranged in different levels. (You illustrated each level in class)
Level 1: Individual organism (Example: you)
Level 2: similar organisms forming a population (Example: your family)
Level 3: different populations forming a community. (Example: all of the families that make up your neighborhood-they all come from different backgrounds)
Level 4: a community and its abiotic environment. This forms an ecosystem. (Example: all of the families and the plants, animals, lakes, ponds, air, dirt, etc.)
Level 5: All ecosystems forming the biosphere (Example: All parts of the world)
-populations are a group of individuals of the same species that live together in the same area at the same time.
-communities are all of the populations of different species that live and interact in an area.
- ecosystems are made up of a community of organisms and its abiotic environment.
-biospheres are the part of the Earth where life exists.
SECTION 2: LIVING THINGS NEED ENERGY
3 classification groups of how organisms obtain their energy
- Producers- use sunlight directly to make food. Most producers are plants.
- Consumers- organisms that eat producers or other organisms for energy.
4 types:
1. Herbivore- a consumer that eats plants. (Ex. grasshoppers, gophers)
2. Carnivore- a consumer that eats animals (Ex. coyotes, owls)
3. Omnivores- Eat both plants and animals. (Ex. Humans)
4. Scavengers- animals that feed on the bodies of dead animals. (Ex. crayfish, worms, crabs)
- Decomposers- organisms that get energy by breaking down the remains of dead organisms. Bacteria and fungi are examples. These are nature’s recyclers.
Food Chains/Food Webs
-food chains represent how the energy in food molecules flows from one organism to the next. Sometimes the energy source comes from many different organisms because rarely do animals eat one type of organism.
- food webs show the many different pathways possible for energy transfer among animals. Read on page 42 for an example and instructions on how to read a food web.
Energy Pyramids
-energy pyramids show the loss of energy at each level of a food chain. The base holds more energy because there are more plants available as an energy source. The next layer has less energy because the number of organisms decreases . The third level decreases in organisms and energy because of the type of organisms present. The top layer has the least number of organisms and the least amount of energy. See page 43 for a diagram.
Wolves and the Energy Pyramid
-Some consumers can control the populations of many other species.
- Wolves eat anything form lizards to elk. When the United States was being settled, gray wolves were almost wiped out. This in turn left no predators for the elk and the elk became overpopulated. This led to overgrazing and starvation to other animals because all of the producers were getting eaten by the elk since they eat producers. In order for everything to be balanced, the U.S. depends on the gray wolves for a consistent energy flow.
Habitat and Niche
- A habitat is an organisms environment in which it lives. An example would be that a wolf lives in forests, grasslands, deserts, and northern tundras. We live the same areas but in houses.
- A niche is an organism’s way of life within its ecosystem. This includes the organism’s habitat, its food, its predators, and the organisms with which it competes. An example would be the wolf’s habitat, grasslands, forest, deserts, etc. and the elk and lizards they eat, and its predators, other carnivores, and the competition of food with these other carnivores. A niche can also include how the organism affects and is affected by the abiotic factors in its environment. We effect our environment by polluting the air and in turn this pollution causes health problems. You can read about a wolves niche on pages 44 and 45 for a more detailed example.
SECTION 3: TYPES OF INTERACTIONS
Interactions with the Environment
- Most organisms produce more offspring than will survive. The biotic and abiotic factors in the environment control population size which causes the same population number to occur year after year. In “Finding Nemo,” Nemo’s siblings were eaten by a shark at the beginning. This is part of the interaction of organisms in its environment. If you noticed, Nemo’s parents produced a lot of eggs and only one of them, Nemo, survived.
- Limiting Factors: Limiting factors are when resources become scarce due to overpopulation of a species. Overpopulation can cause food, water, living space, and other needed resources to deplete or lessen which makes it a limiting factor.
- Carrying Capacity: Carrying capacity is the largest population that a given environment can support over a long period of time. When a population reaches its carrying capacity, limiting factors began to show themselves and the population gets smaller because the resources are not there.
4 Main ways Species/Individuals Affect Each Other:
1. Competition- when two or more individuals or populations try to use the same limited resource, food, water, shelter, space, or sunlight.
2. Predators and Prey- The organism that is eaten is the prey and the organism that eats the prey is the predator. Predators have to be able to catch their prey. Some of them use speed as their adaptation and others used a method of ambushing. Preys have ways of protecting themselves against predators with their own special adaptations. Some are poisonous to other predators or they have speed and run away, they can camouflage themselves, stay in groups, burrow, or hide within the environment.
3. Symbiosis- a close, long-term association between two or more species.
3 types of symbiosis:
- Mutualism: a symbiotic relationship in which both organisms benefit. An example would be a clown fish and a sea anenome. The clown fish benefits by having a shelter inside the sea anenome and the sea anenome benefits because the clown fish keeps it clean.
- Commensalism: A symbiotic relationship in which one organism benefits while the other organism is unaffected. An example would be you and the mites that live on your skin. The mites benefit because they feed off of your dead skin cells and in turn you are not harmed nor are you affected because you do not know they are there.
- Parasitism: A symbiotic relationship in which one organism benefits(parasite) while the other organism (host) is harmed. An example would be a cat and a tapeworm. The tapeworm lives inside of the cat’s stomach feeding off of the nutrients the cat gets from eating food. The cat eventually does not get the nutrients it needs and it will die. The tapeworm is the parasite in this example because it benefits and the cat is the host because it dies and is harmed.
4. Coevolution- a long-term change that takes place in two species because of their close interactions with one another. An example would be ants and a tropical tree. The ants protect the tree on which they live by attacking other herbivores that approach the tree. The tree has coevolved special structures on its stems that produce food for the ants and the ants also live inside other structures on the tree. The tree has coevolved because of this close long-term relationship between the ant and the tree.
