GED110

• the term was first proposed by A.G Tansley in 1935. He defined it as "The system resulting from the interaction of all the living and non living factors of the environment. (Basically, living things and their environment) 

• It consists of the biological community that occurs in some locale, and the physical and chemical factors that make up it's non-living or abiotic environment. 

Examples:

• A pond

• A forest

• An estuary

• A grassland

1. NATURAL ECOSYSTEMS: 

Operates under natural conditions without any major interference by man.

• Terrestrial Ecosystem : Forest, Grassland, Desert  (Basically Land) 

• Aquatic Ecosystem:

a. Fresh Water: Lotic (Running water like; spring, stream, or rivers ) 

  : Lentic (Standing water like; lake, pond, pools, etc.) 

b. Marine Water: Such as deep bodies as ocean or shallow ones as sea or an estuary 

Functions of Ecosystems

The Major Biological Components of Ecosystems: 

A. Producers (Autotrophs)(Self-feeders) 

-Make their own food from compounds that are obtained from their environment

-Are the source of all food in an Ecosystem.

-On land, most producers are green plants. 

-In freshwater and marine ecosystems, algae and plants are the major producers near shorelines.

-In open water, the dominant producers are Phytoplankton (most of them microscopic).

-Most Producers capture sunlight to make carbohydrates (such as glucose) by photosynthesis.

• It is the Science that deals with the interaction between living organisms and their environment.

Basic Behavioral Patterns

• Tropisms- The turning of plants towards or away from the stimulus.

• Reflexes- These are automatic responses of specific body organs or parts of an organism to stimuli 

• Instinct- These are encoded sequences of stereotyped behavior

• Learning- It is the ability to acquire and process new knowledge.

• Reasoning- It is the ability to evaluate and reflect situations sensibly and thereby exhibit reactions that would allow them to interact better with other organism and their environment. 

Two types of Ecosystem:

1. Natural Ecosystem

a. Terrestrial Ecosystem - land

b. Aquatic Ecosystem - bodies of water 

2. Artificial Ecosystem

natural balance is disturbed regularly (regularly because it's still systematic) 

Example: Crop Land System

The 7 Environmental Principles

1. All forms of life are important - all have their own purpose and function. Disruption of these functions may lead to instability or imbalance (like extinction!) 

2. Nature knows best - ecosystems exist because nature has a natural process or cycle to maintain balance (The circle of life!) 

3. Everything is connected to everything else - one animals eats another and another and what remains is recycled! 

4. Everything changes - Though systems exists there are limiting factors or interruptions like human activities

5. Everything must go somewhere - Nothing simply disappears. Like when water evaporates, the dispersed gas is just brought down by rain again! 

6. Ours is a finite Earth- Earth is a closed system where all matter essential to life comes from within it and must be recycled over and over for life to continue

7. Nature is beautiful and we are stewards of God's Creation

Epigenetics

Epi - "above" or "on top of" : so epigenetics refers to modifications that occur on top of your genes

Environmental factors actually cause your cells and genetic code to change over your lifetimes. Your genetic code itself is alwas the same, but genes can be "turned on" or "turned off" 

For example: 

Your diet can cause "epigenetic changes" to your DNA

This is a strand of DNA

• DNA - is a long, ladder-shaped molecule: the famous 'double-helix' shape. Inside our cells, DNA contains all the information needed to make us grow and live. 

Stress Gene Experiment 

See this as an example how gene's can be altered 

1. Baby rats are nurtured by a mother rat - The babies' DNA is tested and epigenetic tags are visible on the stress response gene, turning it "on"

• These rats respond very well in stressful situations for the rest of their lives. 

• The offspring of these rats ALSO have epigenetic tags on the stress response gene: the babies inherit an imprinted gene on which the stress response gene is "turned on" 

2. Baby rats are neglected by a mother rat - The babies' DNA is tested and epigenetic tags are NOT present on the stress response gene, keeping it "off". 

• These rats do NOT respond well in stressful situations for the rest of their lives. 

• The offspring of these rats ALSO have NO epigenetic tags on the stress response gene. 

Are Epigenetic Changes Permanent? 

Short answer: NO, it's always susceptible to change 

Although epigenetic changes may be passed from one generation to another, we know they are dynamic and reversible. This is commonly observed in nature, even in plants. 

During drought, some plants adapt to survive and than pass those adapted genes to the next generation

If the next two or three generations don't eperience another drought, the epigenetic changes are usually no longer passed on. 

Example of how Epigenetics works 

The DNA of twins begins the same, but over the course of their lives, different health choices and environmental stimuli cause the DNA code to change. 

What does this mean for the nature v.s nurture debate?

• That we are not defined by our genes. Our lifestyle choices can actually impact our genetic codes, causing certain genetic traits to express themselves more or less strongly. 

Aesthetic value 

• Provides visual or artistic enjoyment. (Forested landscape or for spiritual meditation like the Prayer Mountains) 

Why is Biodiversity Important? 

• sustains the flow of energy in the food web on earth and contributes to environmental STABILITY. 

• can be described as the resilience to withstand changes (result of natural or human activities) that may occur in the environment 

Population Growth 

• Population - a group of organisms of the same species that live in a certain area

> Ecologists need to know why the number of organisms is increasing or decreasing 

• Birth rate (natality) - the number of births in a population. 

• Death rate (mortality) - the number of organisms that are dying in a population 

POPULATION GROWTH LIMITING FACTORS:

1. Density-depending Limiting Factor 

Factors that regulate population's growth and is influenced by population density 

e.g. when a population reaches a certain size, there won't be enough resources for all of the organisms. This could cause the population to stop growing when it reaches the maximum number of organisms that can be supported or "carried" by the environment. 

• diseases and parasites

• competition for resources 

• predation 

• emigration 

2. Density-depending Limiting Factor 

• Natural disasters, temperature, sunlight, and the activities of humans in the environment 

Biogeochemical Cycles

a.k.a substance turnover or cycling of substances 

• is a pathway by which a chemical substance moves through both the biotic (biosphere) and abiotic (litosphere, atmosphere, and hydrosphere) components of Earth. 

• The term "biogeochemical" tells us that biological, geological and chemical factors are all involved. The circulation of chemical nutrients like carbon, oxygen, nitrogen, and phosphorus, calcium, and water etc. through the biological and physical world are known as "biogeochemical cycles". 

> Cycle : is a series of change which comes back to the starting point and which can be repeated.

Example: Water Cycle 

• Through biogeochemical cycles, elements , chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another.

• In effect, the element is recycled, although in some cycles there may be places (called reservoirs) where the element is accumulated or held for a long period of time (such as an ocean or lake for water) 

Origin: the term "Biome" was suggested by an American ecologist "Frederic Edward Clements" in the year 1916, from the words "biotic community" , to describe the plants and animals in a certain habitat 

Types of Biomes

Aquatic Biome 

• Fresh Water

• Marine

Terrestrial Biome

• Grassland

• Forest

• Desert

• Tundra

• An area of tall, mostly evergreen trees and a high amount of rainfall 

• Major distinct season: winter is absent, and only rainy and dry seasons are present

• The length of daylight is 12 hours and varies little

• Temperature is on average 20-25° C and varies little 

• Incredibly diverse and complex, home to more than half of the world's plant and animal species 

• Covers about one-fifth of Earth's surface

• This biome has a layer of soil that can either be sandy, gravelly, or stony, depending on the type of desert

• Deserts usually get at most 50 centimeters (20 inches) of rainfall a year 

• Organisms that live in deserts are adapted to this extremely dry climate. (e.g. camals) 

• Plants in deserts have adaptations to conserve water. For example, cacti have enlarged stems to store water to utilize it. 

4 main types: 

1. Hot and dry deserts

2. Semi-arid deserts 

3. Coastal deserts

4. Cold desert 

• Tundra is the coldest of all the biomes (Extremely cold climate)

• Means treeless plain

• Noted for its frost-molded landscapes

• Little precipitation 

• Poor nutrients, and short growing seasons. Dead organic material functions as a nutrient pool. 

• The two major nutrients are nitrogen and phosphorus. Nitrogen is created by biological fixation, and phosphorus is created by precipitation. 

• Simple vegetation structures

The Water Cycle

• Water = H2O and is necessary for the life process of all living things 

-Water is found in:

> Earth's surface (including oceans, lakes, rivers, etc.) 

• 97 % is in the ocean! 

• Of the 3% that is freshwater, 2% is frozen in glaciers 

The Main Stages

1. Precipitation:  water falls to Earth as a liquid (usually rain, sleet, or snow) 

2. Infiltration: some water seeps underground from the surface of the Earth

-Aquifer: An underground layer of of permeable rock that can hold water. 

3. Runoff: liquid water that isn't infiltrated runs along the surface and collects in bodies of water

4. Evaporation: sun heats liquid water to vapor and it rises to the atmosphere

5. Transpiration: water rises back into the atmosphere as water vapor from plants

6. Condensation: water vapor condenses to form clouds before participating again.

The Carbon Cycle

• Carbon is the basis of all organic molecules, and is found in a variety of chemical forms.

• Carbon changes chemical forms as it cycles (unlike water, which is always H2O) 

Example: Carbon is CO2 in the atmosphere, but C6H12O6 as glucose in plants

Carbon is found in: 

-Macromolecules - large molecules necessary for life. 

The Main Stages

1. Photosynthesis: plants capture CO2 from the atmosphere and use it to make sugar. 

2. Cellular Respiration: CO2 released into atmosphere as waste from metabolism. 

3. Consumption: one organism eats another for carbon 

4. Decomposition: decomposers break down carbon from dead organisms, recycling it in the soil.

5. Fossilization: converts carbon from once-living organisms into fossil fuels through intense heat and compression.

6. Combustion: CO2 released into atmosphere from burning

The Nitrogen Cycle

• No step is completed without the help of living organisms

• Bacteria is most important living organism in converting nitrogen to different forms 'Fungi and other decomposers breakdown nitrogen-rich waste and put it in the soil 

• Nitrogen, like carbon, takes on a variety of chemical forms. 

It is found in: 

-In the atmosphere in the form of a gas - N2 (elemental nitrogen, plants and animals do not use this form of nitrogen) 

-Macromolecules 

-Fossil Fuels

-Waste

-Soil

The Main Stages

1. Nitrogen Fixation: Bacteria (or lightning) in the soil or water convert nitrogen (from the air or water) into forms that plants can use. 

2. Consumption: one organism eats another and obtains the nitrogen in it. 

3. Decomposition: decomposers, like bacteria, break down dead matter, returning nitrogen to the soil. 

4. Ammonification: Bacteria convert nitrogen from waste (urine and feces) into ammonia

5. Nitrification: Bacteria convert nitrogen in ammonia into nitrates and nitrites to be absorbed by plants in their roots. 

6. Denitrification: Bacteria convert nitrogen in ammonia to N2 so it can go back into the atmosphere