Interactions
Environments and Organisms
1. Ecological Concepts
- Ecology: study of the interactions between organisms and their
environment
- Adapted to environment?
- Energy sources?
- Matter (resources)?
2. Levels of organization in Ecology (Figure from Text)
3. Environment?
- Everything that affects an organism during its lifetime
- Biotic: other organisms of many kinds
- Example: Song bird
- Food: seeds of plants or other fruits, insects
- Competitors: other song birds of the same species for mates,
or competitors for nest spots, food.
- Predators: raptors (hawks, eagles, snakes)
- Abiotic: seasonal signals to migrate, sources of water for
drinking and bathing, dirt for dust baths for antiparasite treatments,
shade for protection from the sun on a hot day.
4. Abiotic Factors
- = Non-living
- Types:
- Energy (ultimately from the sun through photosynthesis)
- Nonliving matter: nutrients (N,P,K)
- Living space: aquatic, dry, rocky, sandy, cave
- Processes: interactions of nonliving matter & energy
- weather and solar patterns: winds, humidity, temperature,
precipitation => all interrelated
- Soil formation (pedogenesis)
5. What limits the growth of a particular species?
- Limiting factors: specific to each type of organism
- Abiotic or biotic
- Examples
- Most phytoplankton (microscopic photosynthesizers) in lakes
are limited by the nutrients N or P
- The growth of wolf populations are limited by the
availability of easy to capture prey items like young or injured grazers
6. Monarch butterflies lay their eggs on milkweed plants.
The larvae eat the leaves: monarchs are limited by number of
milkweeds. (Photo from text)
7. Figure 5.3. Oxygen limits the distribution of some fish
species. Headwaters = cool, high O2; middle, warmer, less O2;
near mouth of stream = warmest, lowest O2
8. Range of Tolerance example = growth of bacteria versus
temperature of the culture
(Figure: bar graph with a "bell " shaped curve showing growth of
bacteria vs. temperature).
9. Previous slide: how to read a graph
- Growth
- measured as change in cell density: cells per milliliter
- Plotted on the Y axis: dependent variable
- Experimental conditions: temperature
- Measured as degrees Fahrenheit (oF)
- Plotted on the X axis: independent variable
10. Graph again with optimal growth and stress pointed out.
11. Habitat - Place
- An organism’s address
- Description of habitat includes
- Soil type
- Water
- Climatic conditions
- Typical (predominant) plant species in the area
- Thus: important physical or biological features of the
environment
12. Moss Habitat: typically cool, moist, shady.
Mosses need a thin layer of water to reproduce sexually. (Figure
5.4)
14. Niche - Role or Job
- Includes all ways an organism interacts with others and the
environment
- Examples
- What an organism eats
- What eats it
- What type of effects it has on the environment
- Beavers build dams across streams
- Rivers back up, slower, deeper water
- Kills trees, creates marshes along edges
- Habitat for ducks, fish, attracts some predators
- If beaver are killed, then dam falls apart and the process
reverses back to a stream.
15: (Photograph from text) Niche of a Beaver