1. Introduction to Ecology

2. Ecology
The study of organisms and their interrelationships with their environment (biotic and abiotic) upon which determine distribution and abundance of organisms.

3. Habitat
A place where an organism lives or can be found.

4. Ecosystem
An interacting system that consists of groups of organisms and their non-living environment with in a boundary.

5. Climate
Definition?
The overriding factor that determines the general nature of an ecosystem.
If the climate is always hot and dry, the soil will be sandy. The plants, animals and other life will be specially adapted for survival in a desert.

6. Climate cont.
If the climate is hot and moist, then there will be many trees, characteristic of a Rainforest. Some animals and insects will be adapted for living in trees. They are called arboreal and include monkeys and spiders.

7. Cont.
If we remove all the spiders from a given ecosystem, the insect population will grow rapidly and destroy forest and crops.
Who do you think would benefit?
What would happen to their population?
Who would be affected then?

8. Levels of Organization
Ecologists tend to label groups of organisms.
Let’s look at a familiar setting for example: Your house is part of a town, this is part of a state, which is part of a country, which is part of a continent.

9. Levels of Organization Cont.
No individual organism lives completely on its own. It may live with other individuals of the same species to form a population.
Several populations living together make up a community.
Several communities in a given area make up a biome.

10. Organization Cont.
Collectively, all the biomes of the planet earth make up the biosphere.
Again, the most basic level of
ecological organization is the individual/species.
A group of individuals of the
same species make up a population.
A community is all the
populations of living
organisms in an area.

11. Biosphere
The biosphere is the region on Earth where all life exists.

12. Niche
Example: Snakes eat mice and other birds and rodents but snakes are also eaten by birds of prey and mice eat grasshoppers and other insects.

13. Niche
A niche may be described in terms of space utilization, food consumption, temperature range and mating requirements.
An organism’s niche would also take into account its behavior. You can think of an organism’s niche as its job/role in the environment.

14. Niche
A beaver is an ecosystem engineer. It cuts down trees and dams up a river which will flood the forest with a pond. Eventually the trees will dies, new species of plants and wildlife will arrive to take advantage of the new conditions. Eventually, this forest will become a meadow. The beaver’s NICHE is the role it plays in shaping the environment. But… it is also a main prey species for predators.

15. Habitat
Niche is not synonymous with habitat. Habitat is a place, niche is a pattern of living. Habitat is the address and niche is the job or occupation.
If two organisms have the same habitat and similar niches, they will compete with each other over the available resources. (food- water -shelter)

16. Habitat
Competition is the struggle between two organisms within their habitat.
If a species can avoid competing they may co-exist. But if they compete, one will eventually drive the other out of the habitat, unless they have slightly different niches.
Example: times of activity