Lesson 3Ecology
& Comparing Ecosystems
November 17, 2010
Why do we need pests?
• Imagine a world without pests!• Summer without mosquitos, a garden without
weeds… that sounds great?!• BUT, how would other organisms be affected?
No Pests!• Some fish and amphibians rely on mosquito larvae for food• Adult mosquitoes are important food source for swallows, robins
and other small birds• Most plants rely on insects for pollination• Some insects help decompose tissues of dead plants and animals-
returning nutrients to the soil• Many insects dig around roots of plants allowing more oxygen to
get to their roots• Garden weeds are important source of food for many animals-
grazing animals would become extinct• Roots of these weeds pump more nutrients into soil’s surface• Some weeds even anchor soil, preventing erosion
Organisms Interact within Ecosystems
• Eco- Greek word oikos, meaning place where one lives
• Logy- Greek word logos, meaning study of• Ecology- study of how organisms interact with
each other.
• Ecological studies can begin at the level of a single organism
• They determine how the individual interacts with its environment and how factors in the environment affect its growth, feeding habits and reproduction.
• There are 2 types of factors in an ecosystem-biotic and abiotic
• Biotic- factors caused by the presence and roles of other living things• Abiotic- non-living factors or influences on organisms (ie. Sunlight, temperature,
strength and direction of wind)
• Organisms do not live in isolation-they usually group with others of the same species
• Population- all of the members of the same species living in the same ecosystem or habitat
• There is usually more than one species in an ecosystem, there is more than one population.
• Community- collection of all the populations of all the species in an ecosystem or habitat ( in a lake there may be populations of pike, perch, tadpoles, mosquito larvae, and algae)
What do ecologists study in a community?
• They study how the biotic factors affect each population
• An ecologist studying a forest community might look at interactions between different types of plants and animals
And if they want to study more?
• The can extend their study to include the physical environment
• The ecologist studying the forest community might examine how much sunlight reaches the forest floor and what affect that has on the plants and animals
Ecotones and Biodiversity
• Ecosystems do not have distinctive boundaries
• Organisms can move back and forth from one to another
• There is usually a grey area between ecosystems where organisms from each ecosystem interact with each other
• This transition area is called and ecotone
• Ecotones guard against extinction• If an organism has only one source of food in
its ecosystem, its own existence is linked to the survival of that species
• Ecotones have more species, giving the organism an alternative food source
Comparing Ecosystems
• What are some artificial ecosystems in your area?
• Artificial ecosystem- planned or maintained by humans
• What are natural ecosystems in your area?• Natural ecosystems- living community is free to interact with the physical and
chemical environment (not maintained or planned by humans, but may not be untouched by humans)
• Text Pages 28-29• Case Study
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