Ecology: The study of Interactions among

Organisms and its environment including:

Abiotic factors are nonliving factors such as temp. soil, air, rocks

Biotic Factors are living parts of the ecosystem

Populations vs. Communities:

A population is a group of organisms of the same species living in a certain area

All populations interacting together in a given area is a community Ex. Frogs + fish + algae =

community

Habitats are:

Place in the ecosystem where an organism lives

Determined by both biotic and abiotic factors Ex. Earthworm = moist soil, dead

organic material

Niche:

The role of the organism in its environment

Includes feeding habits, reproduction, habitat, and what it contributes to its surrounding

Ecosystem is a community and its physical environment including biotic and abiotic factors

Autotrophic and

Heterotrophic Nutrition:

Autotrophs:

Make their own food PRODUCERS Provide food to consumers Most carry out photosynthesis (solar

light energy being converted into food glucose!!)

Ex. Green Plants!! Some producers are chemosynthetic –

ability to create food by using energy stored in inorganic molecules

Autotrophs:

Heterotrophs:

Are also known as consumers

Cannot make their own food Must obtain their food from

their environment

Heterotrophs:

Types of Heterotrophs include:

Herbivores eat only plants

Types of Heterotrophs include:

carnivores eat only meat predators- kill and eat their prey

prey - the animal that is killed and eaten

scavengers feed on dead and decaying meat

ex. Buzzards, crows, hyenas

Types of Heterotrophs include:

omnivores – eat both plant and animals

ex. US!!, bears and…???

Types of Heterotrophs include:

Decomposers (aka. saprobes) get nutrients from breaking down dead plants & animals

Ex. bacteria, fungus, mushrooms

Symbiosis (Symbiotic Relationships):

2 organisms living together where at least 1 organism benefits

3 types of symbiotic relationships:

1. Mutualism2. Commensalism3. Parasitism

Mutualism

mutualism - both organisms benefit from the association

Ex. Humans and bacteria in the digestive track Ex. Fish in sea anemones Ex. Flower and the bee

Commensalism

Commensalism - one organism benefits the other is not effected

(not harmed, no benefit) ex. Remora fish and sharks ex. Orchids/moss living in tree

Parasitism:

Parasitism - one organism benefits at the cost of the other (host)

ex. parasites living in animals (tapeworm, tick)

often cause disease

Energy Flow in an Ecosystem:

Includes: producers (Autotrophs ) make their

own food consumers (heterotrophs) obtain or

eat their food from the environment Decomposers (a.k.a saprobes )

break down left over remains of plants and animals

FOOD CHAINS: Are a transfer or 1

pathway of energy through an ecosystem

Solar Energy from the sun is converted by producers (photosynthesis) into chemical energy or FOOD

FOOD CHAINS cont…

Show the relationship b/w Producers and Consumers Energy is transferred from the producer to

the consumer that eats it. Herbivores are first order consumers gaining

the most energy from the producers Omnivores and Carnivores are secondary

consumers getting left over energy

FOOD CHAINS cont…

The feeding relationship shows the transfer of energy which forms a food chain

The transfer of energy moves from producer to consumer to decomposers Ex. Sun plant grasshopper bird cat

Decomposers

Producers consumers consumers consumers

(plants) (1st level) (2nd level) (3rd level)

Examples of food chains: 

              

              

          

     

Grass grasshoppers robins hawk  

FOOD WEB

food chains (1 pathway of energy) which are interconnected = food webs

Food webs are many food chains interacting together

Each arrow in the food web means consumed (EATEN) by…

FOOD WEB

Energy Pyramids ARE:

Another way of showing the flow of energy in

an ecosystem

Energy Pyramids

Each step in a feeding relationship is

called a trophic level 1st trophic level = producers 2nd trophic level = primary consumers 3rd trophic level = secondary

consumers

The greatest amount of energy is at

the bottom of the pyramid (producers), the least amount of

energy is at the top.

90% of Energy is lost moving at each level, only 10% is transferred to the next level

Some of the Energy is used in cell activities (growth, cell division), the rest is lost as heat

The Carbon Cycle:An exchange of materials (carbon dioxide, oxygen) between autotrophs and heterotrophs

The Carbon Cycle:

Cycles in Nature:

Autotrophs: use the sun’s energy to produce their own food in a process called photosynthesis

In photosynthesis CO2 is absorbed (taken in) from the environment and O2 (Oxygen) is released as a waste.

Cycles in Nature:

Heterotrophs: take in the Oxygen and use it for cellular activities

Releases CO2 into the environment as a waste

The process is called cellular

respiration

The Carbon Cycle:

The Carbon Cycle is a balance between Carbon Dioxide and Oxygen in the air.

Remember…

A population is a group of organisms of the same species living in a certain area

Discussion on Populations: change over time Most stabilize rather than continuously

grow As populations increase in #, it puts

more demand on the resources available such as food, shelter, and water

Environmental factors that limit the size of a population are called limiting factors.

Limiting Factors:

Environmental factors that limit the size of a population

The availability of resourcesEx. Food, water, shelter, oxygen, sun

Density-Dependent Factors:

limit the growth of a population when the population reaches a certain size Ex. Disease, competition, predators, and

food Population Density

The number of organisms in a given area Predation, competition, and the spread

of disease all are influenced by population density

Question:

what happens to the level of competition when the

population density increases?

Predation? Disease?

Population Cont.

predator- prey population cycles

Density Independent Limiting Factors:

limit growth in a population regardless of size

These factors are often climatic events

Ex. Extreme temp, drought, volcanoes flooding

Carrying Capacity:

The largest number of organisms (of one species) that can be supported for an unlimited amount of time

Occurs when # of deaths and births are about equal If a population goes over the carrying

capacity the number of deaths is greater than the # of births

If the population is under the carrying capacity then…

Carrying Capacity

Population Growth Rate Involves:

Birth and Death rate influences

the population growth Life expectancy of humans

Man-72 years Woman-79 years

Population Growth Rate Involve:

Immigration-movement of individuals into a population

Emigration -movement of individuals out of a population

Graphs & Populations

Exponential Model: Describes a population that

increases rapidly after only a few generations

The larger the population gets, the faster it grows

“J” shaped curve

Logistic Model:

Takes Limiting factors into account Includes carrying capacity -the number of

individuals the environment can support over a period of time

Increased birth rates causes growth rates to increase

Growth will decrease when a population reaches the carrying capacity.

Birth rate = Death rate when a population reaches carrying capacity therefore GROWTH

Logistic Population Growth

After discussing topics in ecology such as: the flow of energy,

balance among organisms and populations, what type of impact do you feel humans have on the environment?

Why?