Interaction of Living Things Chapter 12 Page 304 – 325

Everything is Connected Page 306 Everything is Connected Studying the Web of Life All living things are connected in a web of life. Scientists who study the connections among living things specialize in the science of ecology. Ecology = the study of the interactions between organisms & their environment. An Environment Has Two Parts An organism’s environment is anything that affects the organism. It consists of two parts. Biotic = all of the organisms that live together & interact with one another. Abiotic = all of the physical factors that affect organisms living in a particular area. physical factors (water, soil, light, temperature)

Organization in the Environment Page 307 Organization in the Environment At first glance, the environment may seem disorganized. To ecologist, however, the environment can be arranged into different levels. Level 1 = individual organism Level 2 = a population Level 3 = a community Level 4 = an ecosystem Level 5 = a biosphere

Page 308 Population Population = a group of individuals of the same species that live together in the same area at the same time. The individuals in the population compete with one another for food, nesting space, & mates.

Page 308 Communities Communities = all the populations of different species that live & interact in an area. The different populations in a community depend on each other for food, shelter, & many other things.

Page 308 Ecosystems Ecosystem = a community of organisms & its abiotic environment. An ecologist studying the salt-marsh ecosystem would examine how the ecosystem’s organisms interact with each other & how temperature, precipitation, & soil characteristics affect the organisms.

Page 309 The Biosphere Biosphere = the part of Earth where life exists. It extends from the deepest parts of the ocean to very high in the atmosphere, where tiny insects & plant spores drift, & it includes every ecosystem. Ecologists study the biosphere to learn how organisms interact with the abiotic environment – Earth’s gaseous atmosphere, water, soil, & rock. The water in the abiotic environment includes both fresh water & salt water as well as water that is frozen in polar icecaps & glaciers.

Living Things Need Energy Page 310 Living Things Need Energy The Energy Connection All living things need energy to survive. Organisms in any community can be divided into three groups based on how they obtain energy. (producers, consumers, decomposers)

Page 310 Producers Producers = organisms that use sunlight directly to make food. Most producers are plants, but algae & some bacteria are also producers.

Page 311 Consumers Consumers = Organisms that eat producers or other organisms for energy. There are several kinds of consumers. Herbivores = a consumer that eats plants. Carnivore = a consumer that eats animals Omnivores = consumers that eat both animals & plants Scavengers = animals that feed on the bodies of dead animals. They cannot use the sun’s energy directly like producers. Instead, consumers must eat producers or other animals to obtain energy.

Page 311 Decomposers Decomposers = organisms that get energy by breaking down the remains of dead organisms Bacteria & fungi are examples of decomposers. These organisms extract the last bit of energy from dead organisms & produce simpler materials, such as water & carbon dioxide. Decomposers are an essential part of any ecosystem because they are nature’s recyclers.

Food Chains & Food Webs Page 312 Food chain = represents how the energy in food molecules flows from one organism to the next. But because few organisms eat just one kind of organism, simple food chains rarely occur in nature.

Food Chains & Food Webs (Cont’d) Page 312 Food Chains & Food Webs (Cont’d) Food web = the many energy pathways possible in an ecosystem

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Page 313 Energy Pyramids Energy pyramid = a diagram shaped like a triangle showing the loss of energy at each level of the food chain

Page 313 You can see that the energy pyramid has a large base & becomes smaller at the top. The amount of available energy is reduced at higher levels because most of the energy is used by the organism or given off as heat. Only energy stored in the tissue of an organism can be transferred to the next level.

Wolves & the Energy Pyramid Page 314 Wolves & the Energy Pyramid A single species can be very important to the flow of energy in an environment. Gray wolves, for example, are a consumer species that can control the populations of many of the other species in their environment. The diet of gray wolves can include anything from a lizard to an elk.

Page 314 Habitat & Niche Habitat = the environment in which an organism lives Niche = an organism’s way of life within an ecosystem; it includes its habitat, its food, its predators, the organisms it competes with & how the organism affects & is affected by abiotic factors in its environment. The Niche of the Gray Wolf A complete description of a species’ niche is very complex. Gray Wolves are Consumers Wolves are carnivores. Their diet includes large animals, such as deer, moose, reindeer, sheep, & elk, as well as small animals, such as birds, lizards, snakes, & fish. Gray Wolves Have a Social Structure Wolves live & hunt in packs, which are groups of about six animals that are usually members of the same family. Each member of the pack has a particular rank within the pack. The pack has two leaders that help defend the pack against enemies, such as other wolf packs or bears. Gray Wolves Nurture & Teach Their Young A female wolf has five to seven pups & nurses her babies for about two months. The entire pack help bring the pups food & baby-sit when the parents are away from the den. It takes about 2 years for the young wolves to learn to hunt. At that time, some young wolves leave the pack to find mates & start their own pack.

Gray Wolves Are Needed in the Food Web Pages 315 Gray Wolves Are Needed in the Food Web If wolves become reestablished at Yellowstone National Park, they will reduce the elk population by killing the old, injured, & diseased elk. This in turn will allow more plants to grow, which will allow more plants to grow, which will allow animals that eat the plants, such as snowshoe hares, & the animals that eat the hares, such as foxes, to increase in number. “How Wolves Change Rivers” – YOUTUBE!!!!!!

Types of Interactions Page 316 Populations of different organisms vary greatly. The interaction between these populations affect the size of each population. Interactions with the Environment Most living things produce more offspring than will survive. Limiting Factors Populations cannot grow indefinitely because the environment contains only so much food, water, living space, & other needed resources. Limiting factor = When one or more resources becomes scares. Any resource can be a limiting factor to population size.

Carrying capacity Page 317 Carrying capacity = the largest population that a given environment can support over a long period of time. Interactions Among Organisms Ecologists have described four main ways species & individuals affect each other: competition, predators, & prey, certain symbiotic relationships, & coevolution. When a population grows larger than its carrying capacity, limiting factors in the environment cause the population to get smaller.

Page 318 Competition Competition = When two or more individuals or populations try to use the same limited resource, such as food, water, shelter, space, or sunlight. Predators & Prey Many interactions among species occur because one organism eats another Prey = the organism that is eaten Predator = the organism that eats the prey

Predator Adaptations Page 318 In order to survive, predators must be able to catch their prey. Predators have a wide variety of methods & abilities for this. Prey Adaptations Prey organisms have their own methods & abilities to keep from being eaten. Prey are able to run away, stay in groups, or camouflage themselves. Some prey organisms are poisonous to predators.

Page 319 Symbiosis Symbiosis = a close, long-term association between two or more species. Mutualism Mutualism = a symbiotic relationship in which both organisms benefit Commensalism Commensalism = a symbiotic relationship in which one organism benefits & the other is unaffected Parasitism Parasitism = a symbiotic relationship in which one organism benefits while the other is harmed Parasite = the organism that benefits Host = the organism that is harmed Symbiosis = a close, long-term association between two or more species. The individuals in a symbiotic relationship can benefit from, be unaffected by, or be harmed by the relationship. Often, one species lives in or on the other species.

Coevolution Pages 320 – 321 Coevolution Coevolution = a long-term change that takes place in two species because of their close interactions with one another. Coevolution & Flowers Some of the most amazing examples of coevolution are between flowers & their pollinators.