UNIT 6 PART 1: ORGANIZATION IN THE BIOSPHERE The biosphere is the part of earth where living things exist. It is about 20 km thick from the ocean floor through part of the atmosphere. Includes land, sea, and air.

Ecology The branch of biology that deals with the interactions among living things and their environment.

Biotic Factors All living things in the environment and their effects on each other Eats fish Uses grass for nest Bird Fish Man Trees Plants Insects Eats insects Eaten by bird, man Eats fish Mows grass Provide shade Drop leaves Provide food and oxygen Eaten by fish

Abiotic Factors Nonliving things in the environment that determine what types of organisms can survive there AMOUNT OF LIGHT TYPE OF SOIL AMOUNT OF WATER TEMPERATURE

Organization of Living Things Population- all the individuals of one species in an area Community- all the populations in an area Ecosystem- the community and the environment: all living (biotic) and nonliving (abiotic) things

Biodiversity Variety in a biological community is called biodiversity. The greater the biodiversity, the more stable the ecosystem. A rain forest has high biodiversity A tundra has low biodiversity Loss of biodiversity may cause the ecosystem to collapse. Biodiversity

Limiting Factors and Adaptations Some things can limit the growth of a population: Food Water Disease Light Competition Predation These are called limiting factors. Because of variations, some individuals will be better adapted to survive and reproduce than others.

Carrying Capacity When conditions are good populations increase. Limiting factors control the size of a population causing growth to slow or reach equilibrium (birth rate = death rate). The maximum population size that an ecosystem can support (zero growth) is called the carrying capacity.

Types of Organisms Heterotrophs (Consumers) eat other organisms. Herbivores eat plants. Carnivores eat animals. Predators Scavengers Omnivores eat both. Decomposers eat remains of dead organisms. Fungi Bacteria Autotrophs (Producers) make their own food by photosynthesis or chemosynthesis. Green plants and some bacteria

Habitat and Niche Each organism has a particular part of the environment where it lives- its habitat. Squirrel – tree Fox – den Rabbit - hole An organism’s role in the ecosystem (its ‘job’) is its niche. This includes how, where, when it feeds, reproduces, what it eats, where it lives. Habitat is part of niche. Each species has its own niche.

Competition Competition occurs when niches overlap. Eating the same food Reproducing at the same time Interspecific competition occurs between members of different species. Squirrels and chipmunks both eat pine seeds. Intraspecific competition occurs between members of the same species. Choosing mates

ENERGY AND NUTRIENTS IN AN ECOSYSTEM Energy does not cycle through an ecosystem but must be constantly supplied because it gets used by organisms. Much of it is lost as heat. Energy comes from the sun and is made available to all organisms by the producers. Other materials, like carbon, nitrogen, oxygen, and water, do cycle between living things and their environment.

NUTRIENT CYCLES Nitrogen Carbon Water

Food Chain Within an ecosystem there is a pathway of energy flow that always begins with the producers. Producers  herbivores  carnivores  30 (primary, 10) (secondary, 20)

Food Web Many interconnected food chains make up a food web.

Pyramid of Energy and Biomass In a food chain the amount of available energy decreases with each higher feeding level. Only 10% of the energy in one level is passed to the next. Since the total amount of energy decreases, the biomass at each level must also decrease.

Decomposers – organisms of decay Break down the wastes and remains of dead plants and animals. This changes organic matter into inorganic matter that can be reused by other organisms at all levels. The final consumers in every food chain: Fungi Bacteria They are nature’s recyclers.

Symbiosis is a close relationship between two or more different organisms that live together where at least one benefits from the relationship. Mutualism +,+ Parasitism +,- Commensalism +,0 Symbiote benefits Host benefits Host harmed Host unaffected Bees & Flowers Leach & Fish Robin & Tree

Mutualism Both organisms benefit from the relationship: Termites and cellulose-digesting microorganisms Bees and flowers Lichens are an alga and a fungus Legumes and nitrogen-fixing bacteria

Commensalism One organism benefits and the other is unaffected: Barnacles on whales Pilot fish and sharks Cattle egrets and cattle

Parasitism One organism benefits and the other is harmed: Tapeworms Lampreys Mistletoe

Ecological Succession Ecosystems appear stable but they do undergo change. The living things alter the environment so species change over time: the community is replaced. One community changes to another until a stable climax community is reached. This is ecological succession. The climax community stays until there is a catastrophe such as flood or fire. Then succession will begin again. The different biomes are defined by the climax community.

Ecological Succession on Land Primary succession occurs in an area that has no existing life, such as on a bare rock or hardened lava. Secondary succession occurs in an area that has been partially destroyed like a cleared forest. The first organisms to inhabit a community are called pioneers, such as bacteria, fungi and lichens. Pioneers break down the rock and create soil and humus.

Ecological Succession on Land Eventually grasses and small animals move into the area as the soil improves. When these die, the soil becomes richer and can support a greater variety of organisms. The grasses are replaced by small shrubs. Shrubs are replaced by the taller pines. After many years the pines may be replaced by oaks, beeches or maples. These are the dominant species that characterize a climax community.

Ecological Succession on Land

Ecological Succession in Water Small ponds and lakes undergo succession and gradually fill in. Sediments such as soil and leaves wash into the pond, slowly filling it in from the edges. Emergent plants such as cattails and grasses grow around the edges as the pond gets shallower. Shrubs move into the newly formed soil. Trees replace the shrubs as the pond shrinks.

Ecological Succession in Water Chap 25