Unit 5 - Ecology

Relationships and Environmental Factors

Overview• Every living organism

depends on nonliving factors found in its environment and on other organisms living in the same environment for survival.

• Ecology is the study of relationships among living organisms and the interaction the organisms have with their environment

• Biosphere – the portion of Earth that supports life (bio means life, sphere is something round)

Abiotic vs. Biotic Factors• Biotic factors – the living

factors in an organisms environment – Ex – plants, animals,

bacteria• Abiotic factors – nonliving

factors in an organisms environment– Example – temperature,

air, water, light, soil, pH• Organisms are adapted to

surviving in their particular natural environment; if they move to another location with different biotic or abiotic factors, they might die if they cannot adjust quickly

Quick Check for Understanding

• As a class, make a list of at least 5 biotic, and 5 abiotic factors in your environment that are necessary for your survival

Examples

Levels of Organization• To study relationships within the

biosphere, ecologists have organized it into smaller pieces.

• The levels are:1. Organism (a single individual –

one fish, for example)2. Population (when organisms of a

single species share the same geographic location at the same time)

3. Biological community (a group of populations that interact and occupy the same space at the same time)

4. Ecosystem (a biological community plus all of the abiotic factors that affect it)

ex – trees plus water and soil

5. Biome (a large group of ecosystems that share the same climate and have similar communities)

Ex – marine or desert biomes

6. biosphere (all the biomes on Earth combined)

Check for understanding

• Choose an organism – any organism you are interested in

• Describe the levels of organization of that organism

• Share your answer with your partner – random people will be chosen to share their answer

Limiting Factors• Limiting factors – any biotic or

abiotic factor that restricts the numbers, reproduction, or distribution of organisms– Ex – abiotic factors include

sunlight (for plants), climate, water, nutrients, and space; biotic factors would include other plants and animals

• When a resource like food, water, or living space becomes scarce, that factor is what controls the size of a population.– example: snakes feed on mice.

The mice eat grain crops. When the grain crops are plentiful, the snake population will increase. When the crops have a bad year and dry up, there are fewer mice, and therefore fewer snakes.

Carrying capacity…

• The largest population that the environment can support over a long period of time.

• When a population grows larger than its carrying capacity, the limiting factors in the environment cause the population to shrink

Quick Check for Understanding

• As a class, list some abiotic factors that limit plant growth (think about your gardens)

• As a class, list some biotic factors that limit plant growth

• Discuss: how is water a liming factor in certain ecosystems?

Ecosystem Interactions• The interactions between organisms are important in an ecosystem

(remember, an ecosystem is a group of organisms interacting and living together and the abiotic factors in their environment)

• Habitats – an area where an organism lives• Niche – the role or position that an organism has in its environment

(how it gets its food, shelter, and reproduces)

Quick Check for Understanding

• Give 2 examples of a habitat, and an organisms niche within that habitat

• Share your answer with your neighbor• Random answers will be selected to share

with the class

Community Interactions• Organisms that live together in a

community constantly interact – these interactions (and the abiotic factors) shape an ecosystem

• Interactions include competition for basic needs like food, shelter, and reproduction

• Competition – occurs when more than one organism uses a resource at the same time– Ex – during a drought, water will

be scarce for many organisms. The strong organisms compete with the weak for survival; some may die, some may move to another location. If water is plentiful, competition won’t be as fierce. Plants compete for sunlight, animals compete for food or the chance to mate or a place to live

• Predation – when one organisms eats another organism (the predator eats the prey)– Ex – ladybug eating an aphid

Types of Relationships• Symbiotic relationships – a close

relationship between two or more species

• There are 3 different kinds:• mutualism – when both organisms

benefit from each other– Ex – hummingbird and flower; one

gets food, the other gets pollinated

• Commensalism – one organism benefits and the other is neither helped nor harmed– Ex – shark and remora fish; sea

anemones and clownfish• Parasitism – one organism benefits

and the other is harmed– Ex – ticks, fleas, tapeworms,

heartworms• *parasites usually don’t want to kill the

hose, because that’s its home and source of food – but it will weaken it and make it very ill (and eventually kill the host)

Lets Vote

The desert region would be considered a(n)?

A. Ecosystem

B. Biosphere

C. Biome

D. Organism

Lets Vote

A garden in your backyard would be best classified as an?

A. Population

B. Ecosystem

C. Biome

D. Biosphere

Lets Vote

Bacteria living in your small intestine help break down food for nutrient absorption. This is a perfect example of?

A. Parasitism

B. Mutualism

C. Commensalism

D. Ihavenoideaism

Lets Vote

Contact with human feces (poop) can lead to a hookworm infection in the small intestine. If untreated this condition can be fatal. This is an example of?

A. Competition

B. Mutualism

C. Parasitism

D. Fatalism