Ecology Chapter 20

What is Ecology?? Ecology: the study of how living things interact with their environment.

Section 1: Living things & the environment Habitat: Where an organism lives that provides the things it needs to survive Different organisms need different habitats One area may contain many habitats Food, water & shelter are provided in an organism's habitat.

Biotic Factors All the living things in an environment.

ABIOTIC FACTORS All the nonliving things that affect organisms in their environment Examples include: Water Soil Sunlight Temperature & Oxygen

Levels of Organization in an ecosystem:

The smallest level in an ecosystem is an organism (1 individual). All the individuals of one species living in a certain area is called a population.

All the different populations of species in an area make up a community. To be considered a community, populations must live close enough together to interact. Ex) Eat the same food, prey or be preyed on by other species, use the same resources (water, etc.) to live……

Ecosystem: the community of organisms that live in a particular area, along with their non-living surroundings.

What makes an ecosystem different from the other levels? Organisms, populations & communities are all made up of biotic factors, or living things! An ecosystem contains both biotic AND abiotic factors, or non-living things in a particular area.

Population Size There are 4 ways to determine population size: 1. Direct Observation: count all the members of a population. 2. Indirect Observation: looking at signs of organisms instead of actual numbers Example: looking at swallow mud nests, count the number of entrance holes- on average each nest has 4 swallows- multiply

3. Sampling: if population is large or spread over a large area you can’t count them all, you have to make an estimate based on reasonable assumptions.

4. Mark and Recapture Studies: Capture animals and mark them 4. Mark and Recapture Studies: Capture animals and mark them. Then come back two weeks later and capture again. Count how many marked and unmarked that you count. Use a mathematical formula to calculate the estimated total population.

Changes in Population Size Birth & Death Rate: birth rate higher then death rate- population gets bigger Death rate higher then birth rate= population gets smaller

Changes continued… Population size changes when animals move in and out of the population. Emigration is moving OUT of a population Immigration is moving INTO a population

Population Density How many organisms there are in a certain amount of area Pop. Density= # of individuals/ Unit area Example: 20 butterflies in 10 square meters of area, population density would be 2 butterflies per meter squared.

Limiting Factors An environmental factor that prevents a population from increasing. These environmental factors include: Food & water Space Temperature Rainfall

The largest population that an area can support. Carrying Capacity The largest population that an area can support.

Exponential Growth With unlimited resources, populations will grow. This is called exponential growth and is represented by a “J-Shaped” curve.

Logistic Growth Occurs when there are limiting factors that keep population growth balanced. called an “S-Curve”

Interactions Among Organisms

Predator vs. Prey Predator- An animal that hunts, kills, and eats another. Prey- An animal that is killed and eaten by a predator.

Adaptations for feeding Ambush (camouflage) Teeth Night vision Echolocation

Defense Strategies Camouflage False coloring- false eye- predators think organisms head is someplace else Warning coloration: Bright colors to tell predators they are poisonous Protective covering: porcupine

Mimicry The resemblance of one organism to another or to an object in its surroundings for protection from predators.

Symbiosis A relationship between organisms of different species in which at least one organism benefits. Three types of symbiotic relationships: Mutualism Commensalism Parasitism

Mutualism BOTH species benefit from living together Examples: Shark & teeth cleaning fish Crocodiles & cattle egrets Moray Eel & Cleaner Fish *Moray Eel gets a clean mouth *Cleaner Fish gets a meal

Commensalism Clown fish gets protection Anemone is unaffected One species benefits, other is neither harmed nor benefitted Example: Clown Fish & Anemone Clown fish gets protection Anemone is unaffected

Parasitism Worm infects human blood stream Human may go blind One species benefits and the other is harmed Examples: Leeches Ticks Hookworms Tapeworms botfly Taenia worm in human eye Worm infects human blood stream Human may go blind

Competition When a resource is limited organisms must compete for it (due to limiting factors) Usually the organism that competes the best reproduces more often & passes on those genes that allow it to be more successful- NATURAL SELECTION

Niche The role of an organism in its habitat, or how it makes its living. Different from habitat (where it lives)

Succession Series of predictable changes that occur in a community over time

Primary Succession Occurs in an area where NO soil or organisms exist Ex: Volcano erupting, resulting in an area of land

The 1st species to populate that area is called a pioneer species Examples: Moss or lichen Break up the rocks and provide nutrients to the soil Over time seeds land in the soil and grow Grasses and shrubs often replace the pioneer plants

Secondary Succession Series of changes that occur in an area where the ecosystem has been disturbed, BUT soil and organisms are still present Natural disturbances: fire, flooding, tornado, etc.… Human disturbances: logging, farming…