1. Ecology, Part #1

2. Levels of Organization In Ecology
1. Organism – a single individual
2. Population – a group of the same species in the same place at the same time
3. Community – all living things; interacting populations
4. Ecosystem – all biotic and abiotic factors

3. 1. Organism

4. 2. Population

5. 3. Community

6. 4. Ecosystem

7. Habitat A HABITAT is the place where an organism lives its life
Forest, bottom of the ocean, desert, coral reef

8. Niche
A NICHE is an organism’s role in its environment; how it obtains energy
What it eats, how it eats, where it lives, etc.
Most of the time different species occupy different niches (reduced competition)
When two species have the exact same niche, competition will eventually force one species to either die out or find a different niche

9. Lions kill prey and eat meat
Monkeys climb trees and
eat fruits and insects
Whale sharks swim and eat plankton
Trees use sunlight to make food

10. Where Does Earth’s Energy Come From?
The ultimate source of energy for life is the SUN
Plants use the sun’s energy to manufacture food in a process known as PHOTOSYNTHESIS

11. Autotroph
An organism that can make its own food is called an AUTOTROPH
Autotrophs are also called PRODUCERS because they provide the entire food chain with energy
Plants and algae are the most common type of autotroph and they make their own food using photosynthesis

12. Heterotroph
An organism that cannot make its own food is called a HETEROTROPH
Heterotrophs obtain energy by eating other organisms
Heterotrophs are also known as CONSUMERS because they get energy from other organisms.

13. Herbivore An HERBIVORE is a heterotroph that feeds only on PLANTS
E.g. cows horses, zebras, squirrels

14. Carnivore
A CARNIVORE is a heterotroph that feeds only on other heterotrophs (meat, insects, etc)
E.g. Lions, sharks, wolves

15. Omnivore
An OMNIVORE is a heterotroph that feeds on BOTH plants and animals
E.g. Humans, bears, raccoons, skunks

16. Scavenger
A SCAVENGER is a heterotroph that does not kill for food but eats already dead animals
E.g. Vultures, insects, crabs

17. Decomposer
DECOMPOSERS break down and release nutrients from dead organisms (recycle)
E.g. Bacteria, fungus

18. Food Chain
A FOOD CHAIN is a simple model that shows how matter and energy moves through an ecosystem
producers  consumers  decomposers
Arrows on a food chain show the direction ENERGY is moving

19. Trophic Levels Each step in a food chain is called a TROPHIC LEVEL
Trophic levels include:
Producers – autotrophs that produce their own food
Primary Consumers – heterotrophs that eat autotrophs
Secondary Consumers – heterotrophs that eat primary consumers
Tertiary Consumers – heterotrophs that eat secondary consumers

21. Food Web
Most of the time food chains are too simple and don’t show all of the feeding relationships in an ecosystem
A FOOD WEB is a complex model of interconnected food chains that shows all of the feeding relationships in an ecosystem

23. 10% Rule As energy moves up the food chain, 90% of it is lost as HEAT
Only 10% of energy moves up to the next level
The 90% that is lost is used up by the organism for metabolism and movement; only 10% is stored in its tissues
Biomass – The total weight of living organisms at each trophic level
100 kg of grain  10 kg beef  1 kg of human tissue

25. Survival Relationships
In biomes all animals are part of some type of survival relationship
Predator-prey: predators are consumers that hunt and eat other organisms called prey
Predators have no natural enemies

26. Survival Relationships
Symbiosis: relationship in which one species lives on, in, or near another species and affects its survival
Three types:
(1) Mutualism
(2) Commensalism
(3) Parasitism

27. Mutualism Mutualism: type of symbiosis in which both species benefit
Ants living in the tropical acacia trees- trees are protected when ants attack animals that try to feed on the tree and ants receive nectar and shelter from the tree.

28. Commensalism
Commensalism: type of symbiosis in which one species benefits and the other species is neither harmed nor benefited
Spanish moss grows on the branches of trees. The moss gets a habitat and the tree gets nothing.
Whale have barnacles that live on them. The barnacles have somewhere to live, but do not affect the whale.

29. Parasitism
Parasitism: type of symbiosis in which one species benefits and the other species is harmed
Parasite: organism that harms but does not kill another organism
Host: organism that is harmed by a parasite
Ticks feed on dogs, people, etc. The ticks get food (blood) and the hosts lose blood and can be infected with disease.
Best parasites do not kill their hosts…why?

30. Limiting Factors
A limiting factor or limiting resource is a factor that controls a process, such as organism growth or species population size or distribution
Examples of limiting factors include: availability of food, predation pressure, or availability of shelter

31. Carrying Capacity
As a result of limiting factors (like food availability, disease, predation, etc) no population will continue to increase forever
The carrying capacity is the largest number of individuals in a population that a given environment can support

32. Growth Rate
The growth rate of a population is affected by three things:
(1) the number of births
(2) the number of deaths
(3) the number of individuals that enter or leave the population
Immigration – individuals that enter the population
Emmigration – individuals that leave the population

33. Human Population Growth
If birth rate is greater than death rate, population will grow
If death rate is greater than birth rate, population will decrease
Current human population growth is exponential
Will the population continue to grow unchecked?

34. Human Population Growth Discussion
Human (or any species) growth cannot continue unchecked-why?
What resources do we need to survive as a population?
Are we just concerned about longevity of life? Or do we also care about anything besides physical necessities?
How does human population growth affect biodiversity?

35. Logistic Growth
As resources become less available, the growth of a population slows or stops.
An s-shaped curve of this growth pattern is called logistic growth

36. What can affect population size: Disease
Competition for limited resources, predation, and disease can all affect the size of a population
EX: Dutch Elm Disease – Elm trees are attacked by a fungus spread by a beetle. Result: many elm tree populations have been decimated by this fungus
EX: Pfiesteria- a toxic heterotrophic dinoflagellate associated with fishkills and algal blooms.