College Biology - Ecology Unit

Test 1

Inference

Logical explanation using observations.

Observation

Something you use your senses to notice.

Independent Variable

What you change or control in an experiment to see if it affects something else (cause)

Dependent Variable

What you measure in an experiment or study to see if it changes in response to something else (effect)

Null Hypothesis

When there is no result in the experiment (things are often equal)

Population

The number of people living in a specific place

Population Density

A simple measure of how many people live in a specific area

Population Density Formula

Population Density = Total Population / Total Land Area²

Growth Rate (R)

Growth Rate = Birth rate - Death rate

Logisitic Growth

Population stabilizes at a certain level (aka “K”)

Carrying Capacity (K)

Number of individuals in a population that an area can support

Exponential Growth

When a population grows faster over time because the number of new individuals added in each step is proportional to the current total

K-Selected Species

• Do not seek out new environments

• Population is relatively around “K”

• Care for their offspring

• Density dependent (as the population increases, limiting factors bring the population back down)

R-Selected Species

• Opportunist species

• Populations react to variations in environment

• Produce many offspring fast

• Do not provide care for young

• Density independent (population density does not affect the population)

Survivorship Curves

A graph that plots the number or proportion of individuals surviving in a population at each age

Survivorship Curves [X-Axis]

Relative Age (young, middle, old)

Survivorship Curves [Y-Axis]

Number of survivors

Three Types of Surviorship Curves

Type 1: K-Species

Type 2: Linear Line 

Type 3: R-Species

Communites

All the interacting populations of different species living and interacting in a particular area or habitat

Ecological Dominant

Species that are most abundant in certain ecosystems (there are the most of them)

Keystone Species

Species that may not be numerous but whose absence has a significant impact on the ecosystem.

Biodiversity

Range of species in a community

OR…

Diversity of species in a given area

Biodiversity Index

Biodiversity Index = # of different species / total # of organisms

Biodiversity Index (Transect Method)

Estimates the variety of species in an area by sampling along a straight line

[Example: (2/3 + 4/6 + 1/5) / 3]

Habitat

Physical surroundings of a species

Niche

An organism’s role in its enviroment

Interspecific Competition

Between two or more different species

Intraspecific Competition

Between members of the same species

Competitive Exclusion Principal

No two species can share the same vital resource for long periods of time

Resource Partitioning

Species divide up scare resources

AND…

Species adapt and specialize 

Symbiosis (has 4 types)

Two species live close together and at least one benefits

Symbiosis 1: Predator / Prey

One organism feeds on another (+, -)

Predators are dependent on prey

Symbiosis 2: Parasite / Host

Parasite feeds on or lives in the host (+, -) or (+, 0)

Symbiosis 3: Mutualism

Interaction between individuals of two species that is beneficial to both (+, +)

Symbiosis 4: Commensalism

Interaction between two species in which one benefits while the other is neither harmed nor helped (+, 0)

Productivity

The rate at which living matter (biomass) is created by an ecosystem

Mimicry

One species evolved to assume the appearance of another

Example of Mimicry

Batesian vs. Mullerian

Primary Succession

Starting point is little to no life

• Soils lacks nutrients

• Begins with the arrival of a pioneer species

Secondary Succession

The final state of a habitat has been disturbed

• Life remains and the soil has nutrients

Pioneer Species

The first organism to settle in a brand new or disturbed habitat

Lichen

A complex life form that is a symbiotic partnership of two separate organisms, a fungus and an alga (A = food, F= home) & (+, +)

Climax Community

The stable community at the end of a succession

Aquatic Succession

A body of water gradually fills in with sediment and organic material, transforming into land-based ecosystem like a forest over a long period

Eutrophication

The gradual increase in the concentration of phosphorus, nitrogen, and other plant nutrients. Algae begins to bloom, and bacteria breaks it down using dissolved oxygen in the water. This eventually suffocates fish.

Capture / Mark / Recapture

Wildlife estimation method where you capture a sample of animals, mark them with a tag or paint, and then release them back into the population (Later on, you’d catch them again)

Estimated Population Formula

P/M = p/m

Estimated Population Variables Meaning

• P = estimated population

• M = marked Day 1

• p = number caught Day 2

• m = marked Day 2

Estimated Population Example

x/6 = 5/3

Bd (Batrachochytrium dendrobatidis)

A deadly aquatic fungus that infects frogs and other amphibians

How to Find “Q” in WQI (Water Quality Index)

Look at lab number, and follow table / chart

How to Find “T” in WQI (Water Quality Index)

Weighting Factor x “Q”

Ecosystem

Fundamental Unit of Ecology

Abiotic Factors

Non-Living Things

Abiotic Factors Examples

1. Sunlight

2. Percipitation

3. Temperature

4. Soil

Biotic Factors

Living things

Biotic Factors Examples

1. Plants

2. Animals

Density Independent

Population density does not affect the population

Density Dependent

As the population increases, limiting factors bring the population back down

Carbon Cycle

Carbon has been transferred from a fixed state, stored in fossil fuels, to the atmosphere.

• Plants and animals release CO² through cellular respiration

• Plants take in CO² and store it in their tissues

Assimilation

The process where organisms convert inorganic carbon, mainly atmospheric carbon dioxide, into organic compounds which are used for energy and structure

Nitrogen Cycle

Describes how nitrogen moves between the atmosphere, soil, and living things

Nitrogen Cycle Steps

1. Nitrogen from the atmosphere is absorbed into a plant (N2)

2. Nitrogen Fixing Bacteria

3. Ammonia (NH3)

4. Nitrification (NO3)

5. Dentrification

Nitrogen Fixing Bacteria

Stored in some plants’ roots (ex: Legume)

Ammonia (NH3)

When plants and animals die, decomposers (fungi and bacteria) break down their organic matter

Nitrification (NO3)

Turns into nitrogen usable by plants

Dentrification

Other bacteria convert nitrates back into nitrogen gas, which is then released into the atmosphere, starting the cycle anew. 

Water Cycle

The water cycle is the continuous movement of water on Earth

Water Cycle Steps

1. Evaporation

2. Condensation

3. Percipitation

4. Collection

5. Transpiraton

Evaporation

Water turns into vapor and rises

Condensation

Vapor cools and forms clouds

Precipitation

Water falls from clouds as either rain or snow

Collection

Two options:

• Runoff - Water flows into rivers, lakes, and oceans

• Seepage - Goes into ground

  • Can turn into “uptake” or “ground water”

Transpiration

Plants release water vapor from their leaves

Abiotic Parameter (from WQI lab): Turbipity

How cloudy the water is - we want low numbers

Abiotic Parameter (from WQI lab): Change in Temperature {often expressed with a triangle}

Measurement in change of temp. in two different areas - want as close together as possible

Abiotic Parameter (from WQI lab): pH

How acidic or basic the water is - want close to 7

Abiotic Parameter (from WQI lab): Nitrates

Measure of nitrogen in water (can indicate fertalizer run-off) - want low levels

Abiotic Parameter (from WQI lab): Phosphates

Measure of phosphates in water (causes extra algae growth) - want low levels

Abiotic Parameter (from WQI lab): Dissolved Oxygen

The oxygen available for living things to breath - want high numbers

Abiotic Parameter (from WQI lab): Conductivity

Amount of salts [how water can conduct electricity] - want low levels

Important Abiotic Parameters (from WQI lab) Ranked

• Dissolved Oxygen (0.17)

• pH (0.11)

• Nitrates and Phosphates (0.10)

• Turbidity (0.08)

• Change in Temp. and Conductivity (0.07)

Producer

Organisms that make their own food (plants)

Consumer

Cannot produce food - must eat other plants / animals for energy

Herbivore

Eat only plants

Omnivore

Eat plants and meat

Carnivore

Eat only meat

Decomposer

Organism that breaks food down into inorganic compounds

Trophic Levels

Food Levels - has 5

Food Chain

Energy travels upwards

1. Quaternary Consumer

2. Tertiary Consumer

3. Secondary Consumer

4. Primary Consumer

5. Primary Producer

Food Web

All the food chains in a single ecosystem.

Energy Flow

Energy is not recycled like natural substances

• Transferred and released as heat

10% Rule

Only 10% of energy moves up in the food chain

Gross Primary Production

The amount of material that a plant produces from photosynthesis

Net Primary Production

The amount of material a plant actually accumulates from photosynthesis

Soil Pyramid - How to Draw Lines

• Clay - Straight Across

• Sand - Upwards Diagonal

• Silt - Downwards Diagonal

Soil Calculations Example

(Variable in cm {a, b, or c} / Total cm) x 100 = % of soil, silt, or clay

Simpson Biodiversity - what does n and N stand for

n - # of each organism

N - total # of all organisms