Ecology

The study of … Relationships between organisms and their physical environment Interactions of living things with their environment

Ecological Organization The relationships between organisms and their environment can be considered at various levels Population Community Ecosystem Biosphere

Ecological Organization Population - all members of a species living in a given area Community - all interacting populations in a given area Ecosystem - all the members of a community along with the physical environment in which they live Biosphere - portion of Earth in which all living things exist – water, soil, air

Characteristics of Ecosystems Requirements of Ecosystems An ecosystem is a self-sustaining unit when the following two conditions are met There must be a constant flow of energy into the ecosystem and there must be organisms within the ecosystem that can use this energy for the synthesis of organic compounds There must be a cycling of materials between the living organisms and the nonliving parts of an ecosystem

Characteristics of Ecosystems Abiotic Factors of Ecosystems The abiotic factors of the environment are the physical factors that sustain the lives and reproductive cycles of organisms Examples: intensity of light, temperature, amount of water, type of soil, availability of minerals Abiotic factors in an environment determine the types of plants and animals that can exist Abiotic factors = limiting factors

Characteristics of Ecosystems Biotic Factors of Ecosystems The biotic factors of an ecosystem are all the living things that directly or indirectly affect the environment There are many interactions among organisms in an ecosystem including nutritional and symbiotic relationships

Characteristics of Ecosystems Nutritional Relationships – involves the transfer of nutrients from one organisms to another within an ecosystem Autotrophs – can use energy to synthesize their own food Heterotrophs – cannot synthesize their own food, must obtain nutrients from other organisms Saprophytes – obtain nutrients from the remains of other organisms – bacteria and fungi Herbivores – animals that feed exclusively on plants Carnivores – animals that consume other animals Omnivores – animals that consume both plants and animal matter

Characteristics of Ecosystems Symbiotic Relationships Symbiosis – close relationship between two or more organisms living together that may or may not be beneficial to the organisms involved

Characteristics of Ecosystems Symbiotic Relationships Commensalism – relationship in which one organism benefits while the other is neither helped nor harmed Barnacles living on whales Mutualism – relationship in which both organisms benefit Nitrogen – fixing bacteria living in the roots of legumes Parasitism – relationship in which one organism (parasite) benefits while the other (host) is harmed Athletes foot fungus, heartworm in dogs

Energy Flow Relationships The pathway of chemical energy from food through the organisms of an ecosystem are represented by food chains and food webs Food Chain – a representation of the transfer of energy from green plants through a series of organisms with repeated stages of eating and being eaten Organisms in a food chain are described as producer, primary consumers, secondary consumers and decomposers

Energy Flow Relationships Producers – organisms that synthesize organic compounds. All energy for the community is synthesized by producers Consumers – all heterotrophs Primary consumers are herbivores Secondary consumers are organisms that feed on primary consumers – carnivores Decomposers – organisms that break down the remains of dead organisms and organic wastes. Return substances to the environment so they can be used again

Energy Flow Relationships Food Chain

Energy Flow Relationships Food Web Representation of various food chains in a community that are interconnected Food webs have the same levels of organisms (producers, consumers, decomposers) as food chains, but the flow of energy and materials is much more complex

Energy Flow Relationships Food Web

Energy Flow Relationships Pyramid of Energy Illustrates the loss of usable energy at each feeding, or trophic level Greatest amount of energy is present in the producer level Only a small portion of this energy is passed on to the primary consumers and only a small portion of that energy is passed on to secondary consumers

Energy Flow Relationships

Carrying Capacity In every ecosystem there is a limited amount of resources which limits the number of organisms that an ecosystem can support The maximum number of organisms of a particular type that can be supported in an area is known as the carrying capacity

Niche Niche – the role that a particular species fills in its habitat. Includes type of food, where and how it lives, where and how it reproduces, and its relationship with other species in the area When two species compete for the same niche the one that is more successful at utilizing the available resources will out compete the other

Cycle of Materials Review Book pages 10 – 11 Questions 67 – 77

Ecosystem Formation Ecosystems, both living and nonliving, tend to change over long periods of time until a stable ecosystem is formed Succession The replacement of one kind of community by another Ecological succession is usually a long process The kind of stable ecosystem that eventually develops in a particular geographical area depends on the regions climate

Ecosystem Formation Pioneer Organisms First plants, or plantlike organisms, to populate an area Lichen and algae are typical pioneer organisms that can be found on bare rock Since plants are the basic source of food for a community, the types of plants present determines the types of animals that can live in the community

Ecosystem Formation Climax Community Succession ends with the development of a climax community in which populations of plants and animals exist in balance with each other and with the environment The climax community will remain stable until a catastrophic change (volcanic eruption, forest fire) alters or destroys it Succession will begin again leading to a new climax community

Ecosystem Formation Succession

Biodiversity The presence of a wide range of different species of organisms living and interacting with each other and with their nonliving environment Biodiversity is required for a stable community or ecosystem

Biodiversity Each organisms plays a variety of roles that contribute to the overall stability of the ecosystem The removal of any one species from its natural environment may have profound negative effects on the overall health of the ecosystem

Biodiversity Biodiversity also increases the likelihood that at least some organisms would be able to survive a catastrophic event Ecosystems that are high on biodiversity all contain a wealth of genetic material that may have beneficial uses in medicine, and agriculture

Biomes Review Book pages 14 – 17 Questions 93 – 106

Humans and the Environment Humans, more than any other organisms have the ability to change the environment Activities of humans can lead to positive or negative effects

Humans and the Environment People Affect the environment Negative effects of humans on the environment Human population growth The population has grown faster than the food- producing capacity resulting in hunger and starvation More people move into and alter wilderness areas resulting in loss of natural habitats

Humans and the Environment Human activities including: Over-hunting Results in extinction of some species and endangerment of others Importation of organisms Loss of biodiversity because there are no natural enemies or competition Exploitation of wild organisms Deforestation has led to habitat loss for wildlife Elephants have been over-hunted for their ivory tusks

Humans and the Environment Poor land-use practices Increased building of cities and suburbs has reduced the amount of farmland and natural habitats Technological oversights Contributes to pollution of air, land, and water Chemical wastes Thermal pollution Exhaust wastes

Humans and the Environment Major air pollutants have led to: Increased levels of carbon dioxide Global warming Ozone layer depletion Formation of acid rain

Humans and the Environment People protect the environment Positive impacts of humans on the environment Population control Conservation of resources Reforestation projects Pollution control Laws have been passed to control the pollution of air and water Hybrid cars

Humans and the Environment Species preservation Endangered species are becoming protected Biological control Use of natural parasites to kill harmful insects Biological control reduces the use of chemical pesticides