1. Introduction to Ecology

2. Organism Species An individual living thing
A group of the same organisms that are able to breed and produce fertile organisms.

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

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

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

6. Two parts of an Ecosystem Biotic and Abiotic
factors that are or were alive/living in an ecosystem.
Examples: animals, plants, insects, bacteria, fungi, and dead organisms.

7. Abiotic Factors in an environment that are not or never were alive.
Examples: rock island, gases, water, sun, minerals and temperature.

8. Levels of Biological Organization
It is important to remember that all
parts of an ecosystem are interrelated.
Each part is affected by all other parts.
If we remove one species from an
ecosystem, there could be severe
consequences for that ecosystem.

9. 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?

10. 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.

11. 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.

12. 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.

13. Organization Cont.
A biome is a large geographical area with a similar climate.

14. Biosphere The biosphere is the region on Earth where all life exists.
Biodiversity is the degree of variation of life. It is a measure of the variety of organisms present in different ecosystems. This can refer to genetic variation, ecosystem variation, or species variation (number of species) within an area, biome, or planet.

15. Habitat and Niche
Each organism confronts the challenge of survival in a different way.
The niche an organism occupies is the sum of all the ways it utilizes the resources of its environment.
Part of this role may be played as the predator and part may be played as the prey.

16. 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.

17. 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.

18. 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.

19. 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)

20. 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

21. Different Niches to avoid competiton:
Nocturnal – active at night
Diurnal - active during the day
Crepuscular – active at dawn and dusk

22. Competitive Exclusion
If two different species compete for the same food source or reproductive sites, one species may be eliminated. This establishes one species per niche in a community.

23. Different Niches to avoid competiton: cont…
Migration – moving from one area to another to use resources
Hibernation – reducing activity severely for a period of time.

24. Ecological Succession
Ecological succession is the observed process of change in the species structure of an ecological community over time.
Two different types of succession—primary and secondary—have been distinguished.

25. Primary Succession
Primary succession occurs in essentially lifeless areas—regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier.

26. Secondary Succession
Secondary succession occurs in areas where a community that previously existed has been removed; it is typified by smaller-scale disturbances that do not eliminate all life and nutrients from the environment.