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Ecology

Ecology is the study of interactions between organisms and their environment.

Ecology entails consideration of  biotic factors (other organisms

that include prey, predators,

 parasites, etc.)

and

…. abiotic factors (such as temperature, light, and water).

Ecology is not environmental

activism or “tree-hugging.”

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Biology-Exploring Life

• Biosphere- on Earth that support life.

• Ecosystem-all living (non-living) in an area

• Community-all living organisms in thatarea

• Population – individuals from one species

• Organism –one living thing

• Organ System-digestive, cardiovascular…

• Organs,->tissues, ->cell,->organelle,->molecule,-> atom

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Ecology

Organization levels of biology.

Ecosystem

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Levels of 

Ecological

Investigation

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Ecosystem (ECS)

• Complex web of relationships (Fig 1.2).• Producers, Consumers, Decomposers.

 – Producers provide food for ECS• Plants-photosynthesis (light, O2/CO2, H2O, sugar,

minerals).

 – Consumers consume plants, animals, O2. Returnwaste like CO2, minerals, phosphate

 – Decomposers bacteria, animals (worms) and fungibreakdown dead organisms to minerals for plants

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Ecosystem Dynamics

The Operation Involves Two Processes:

1. Recycling Nutrients

2. Energy Flow

• Nutrients: Phosphorous, CO2, O2, H2O,

minerals from air and soil to plants,

animals and decomposers then Recycleback to air and soil! 

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Ecosystem Summary

• Energy Conversions…

 –Flow of pure energy (light and heat) throughECS (enters as light, exits as heat).

• This all happens between and within organisms

»Understand Figure 1.2

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Community Ecology

Community ecology examines the question of how populations interact.

Questions include:

What are the types of 

species and their numbers

within a community (i.e.

community structure)?

Are there especially critical species for maintenance of the community?

What is the relationship (predator, prey, parasite) between species within

the community?

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Biogeochemical Cycles

Moving, growing, reproducing requires energy. The

exchange of energy between an organism and it’s

environment involves transformation of one form of 

energy to another.

This is accomplished by biogeochemical cycles. This is

the movement of a substance (for example, water, carbon,

nitrogen, or phosphate) through the biotic (living) and

abiotic (non-living) environments.

Biogeochemical cycles are a key component of ecosystems

ecology.

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The Carbon

Cycle

Understanding of 

the carbon cycle is

critical for global

climate change, yet

it remains

incomplete.

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The Nitrogen Cycle

 Note the key role of 

mutualism between

nitrogen-fixing

 bacteria and their  plant hosts.

 Not shown is the

huge contribution of anthropogenic (man-

made) ammonia and

nitrates.

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The Water Cycle

Only about 40% of precipitation on land comes from water evaporated over oceans; roughly 60% comes from transpiration of water through plants.

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Cells-Structure/Function

Prokaryotic & Eukaryotic Cells (Figure 1.3)• Characteristics

1. Lowest level that sustains life;

2. Regulates own environment;3. Consumes and use energy;

4. Responds to external environment;

5. Maintains it’s internal environment(“Structural Level”…has separate organs) ;

6. Reproduces;

7. Repairs itself.

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Cells-Structure/Function

• Structural level is basis for more complex

levels/functions of higher life organisms…

called emergent properties.

• These complex organizations are called

Systems. Thus Cells, Organisms and

Biosphere, Ecosystems are systems.

• Thus, cells are the basic STRUCTURAL

AND FUNCTION UNITS OF LIFE!!!

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The key to every

 biological problem mustfinally be sought in the

cell, for every living

organism is, or at some

time has been, a cell. E.B.

Wilson, 1925

Why Study Cell

Biology?

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Cells are Us

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Cells are Us

Cilia on a protozoan Sperm meets egg

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Cells are Us

A person contains about 100 trillion cells.

That’s 100,000,000,000,000 or 1 x 1014  

cells.

There are about 200 different cell types inmammals (one of us).

Cells are tiny, measuring on average about

0.002 cm (20 um) across. That’s about

1250 cells, “shoulder-to-shoulder” per 

inch.

nerve cell

Red and

white blood

cells above

vessel-forming cells.

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Cells-Prokaryotic & Eukaryotic

1. Prokaryotic

• Simpler and smaller than Eukaryotic

• Contains no membrane-bound nucleus (but has DNA)

• Bacteria are good example• Few less internal structures (organelles)

1. Eukaryotic

• Many internal compartments & membranes

• Has nucleus and DNA

• Has many organelles

• We are Eukarya Domain!!!!

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Us vs. Them

-Eukaryotes

and

Prokaryotes

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Two Fundamentally Different Types of Cells

A prokaryotic cell

A eukaryotic cell

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Questions

• Which of the following levels of biological

organization includes all others on this

list?

 – Cell, Molecule, Organ, Tissue

• Explain how photosynthesis of plants

functions in both the cycling of chemical

nutrients and the flow of energy in an ECS

• Why are cells the basic units of life?

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Common Features of Life

1. DNA is primary common feature.

 – 2 chains coiled together in double helix

 – Contains 4 building blocks (letters) for 

“alphabet of inheritance”. Genes are

combinations of these blocks, thousands of 

letters long.

 – In DNA they are Adenine, Guanine,Thymine, Cytosine or A, G, T, C

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What’s So Special About DNA?

DNA is one of the most boring macromolecules imaginable

- its made of only four building blocks and has a perfectly

monotonous structure.

Worse yet, DNA just sits there - it doesn’t catalyzereactions or build the cell or organism.

So, what’s so good about DNA?

The answer lies in DNA’s ability to store and copy

information.

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Winners of the Race to Learn DNA’s Structure – Watson and

Crick 53 Years Ago

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Two Views of the Double Helix

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How Can DNA Store and Copy Information?

Key properties that allow these neat tricks are that DNA is a:

DNA is also capable of occasional change, and

occasionally, change is good.

double stranded molecule ….

…. held together by complementary bases …..

…… that pair through simple rules.

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Building DNA Building Blocks

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Common Features of Life

6. Evolution

• The capacity of a species to change

• It’s a unifying feature of life• Estimated that life is about 4 billion

years old.

Now let’s examine the “Diversity of Life.”

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Diversity of Life

• Vertical view refers to Biosphere, ECS,

Community, Population, Organisim, etc.

• Horizontal view sees broad view of 

organism including over 1.8 known

species, grouped by similarities.

• Taxonomy names and puts all species

into categories starting with 3 domains,

then 6- >dozens of Kingdoms etc.

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Two Views of Life’s Organization – Domains and Kingdoms

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3 Domains subdivided by kingdoms

1. Bacteria - Comprised of Prokaryotes

2. Archaea – Like bacteria, comprised of Prokaryotesthat live in extreme environs.

3. Eukarya – Comprised of Protists, (mainly single

celled & photosynthetic), Protozoans (eat

organisms) Plantae, Fungi, and Animalia.

Bacteria and Archaea used to be considered almost

similar but since DNA became available, now

considered separate.

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Life’s History

and Diversity

The Big Picture

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What’s the Domain Archaea?

The Archaea are one of two groups of prokaryotic

organisms (Bacteria are the other group).

Archaea are best known for living in spectacularly inhospitable environments, but

they also occur in great numbers in less extreme conditions.

Much remains to be learned about this recently appreciated “third” life form.

Although Bacteria and Archaea are both prokaryotes, Archaea are even more

different from bacteria than they are from us.

Prismatic Pool, Yellowstone Park – Another “Hot” Site for Archaean

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Prismatic Pool, Yellowstone Park Another Hot Site for Archaean

Extremophiles

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Bacteria – the Most Abundant Cells

There are more bacteria in your mouth than there have

 been people living since the dawn of humans.

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A Sense of Scale and Abundance – Bacteria on the Head of a Pin

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What Good Are Bacteria?

Bacteria are essential for many processes we depend on – sewage treatment,

cheese production, antibiotic production, and biotechnological processes like

gene cloning and protein production.

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Questions

• What is the chemical basis for all life’s

kinship?

• To which of the three Domains of life do

we belong?

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Evolution

• 1859 Charles Darwin published “Origin of Species by Means of Natural Selection.”

• Essential inheritable small variations

exposed to environmental factors could leadto huge changes in species that confer reproductive success.

•This is a Theory often in conflict withanother theory called: “Intelligent Design.”

• Thus, Evolution not a creative process(unlike Intelligent Design).

E l i

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 Nothing in biology makes sense except in

the light of evolution. – Theodosius

Dobzhansky

Evolution

Charles Darwin in later years

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Darwin’s Observations and Inferences

Observation 2: Left unchecked, the number of 

organisms of each species will increase exponentially,

generation to generation.

Observation 1: Individuals in a population vary in

many inheritable traits.

Observation 3: Environmental resources are limited, so individuals are unequal in their 

ability to survive.

Inferences: 1. Today’s species arose from a succession of ancestors “Decent with

modification” 2. Production of more individuals than can be supported by the environment

leads to a struggle for existence among individuals, with only a fraction of offspring

surviving in each generation. Those whose traits are best suited for an environment will leave

offspring….NATURAL SELECTION

E l ti ’ C P i i l

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Evolution’s Core Principles

2. Natural selection.

3. Adaptation. Leads

to multiplication.

1. Varied inheritable

traits (genes)

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Tree of Life

• Darwin said that natural selection over 

time would give rise to 2 or more species.

• If isolated, (Galapagos Island), one

species could then give rise to multiple

species as they adapted over generations

to different geographies.

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Scientific Methods

• At the heart of science is inquiry. No set

formula for successful inquire…methodology

is varied.

• 2 Main types of inquiry – Discovery

 – Hypothesis-based

• Each has there own important value to man’sknowledge base (Jane Goodall).

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Discovery Science

• Leads to conclusions based on “Inductive

Reasoning.”

• From this we derive generalizations from a

large number of observations.

• “The sun always rises in the east”

• “All organisms are made of cells”

 – This came from generations of observations.

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Hypothesis Based Science

• The observations and inductions fromdiscovery science compell us to seek“what causes” the observations we made.

• Example: What caused the finches todiversify on the remote island?

• In HBS, A hypoethesis that can beTESTED is formed from a well-basedquestion. based from observation. IT isTESTABLE!!!

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Hypothesis

• This type of science uses DEDUCTIVE

REASONING.

• This is somewhat opposite of inductive.

Starting from a general premise (not an

observation), we extrapolate to results we

should expect if our premise is true.

• It uses “if”… “then” logic.

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