Ecology and Populations HS-LS2-2

Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales.

HS-LS2-1

Use mathematical and/or computational representations to support explanations of factors that affect carrying capacity of ecosystems at different scales.

*Notes taken and adapted from biologycorner.com

Driving Questions

Question: What determines how many species live in a given place?

What determines how large each population can grow?

4.1 What is Ecology?

ECOLOGY - the study of interactions among organisms with each other and with environment

BIOSPHERE - portion of planet where life exists

LEVELS OF ORGANIZATION

Species - individuals that can breed with one another

Population - all the individuals of the same species (ducks) in an area

Community - all the different species in an area (ducks + maple trees + dragonflies)

Ecosystem - the community plus the physical factors in an area (ducks + maple trees + dragonflies + temperature + soil + rainfall)

Biome - large area that has a particular climate, and particular species of plants and animals that live there (tundra)

Biosphere - the part of the earth that supports life

Organism

Organism

Population

Population

Community

Community

Ecosystem

Ecosystem

Biome Biosphere

Some Animals Are More Equal than Others

Consider the following ideas as you watch (take notes)

1.)Green World Hypothesis

2.)Keystone Species

3.) Trophic Cascades

4.) Hypothesis and experimentation

Ecologist

Ecologist attempt to solve real-world problems related to the environment

Might Study:

Effects of a forest fire

Number and location of whales

Reasons for frog deaths in a pond

How pesticides affects bees

How changing temperatures affect plants

Ecological Methods-how do we study ecology?

Observation

Experimenting

Modeling –models are used to make predictions

4.2 Energy Flow

Autotrophs (producers) –capture energy and convert to “food”

Plants

Heterotrophs (consumers)-must eat things

animals

Types of Consumers

Herbivores: Eat only plants

Carnivores: eat animals

Omnivores: eat both plants & animals

Decomposers: break down organic matter

Sunlight is the main source of energy

Photosynthesis uses light energy to make “food”

Do you remember the equation for photosynthesis?

Chemosynthesis-makes food from chemicals (some bacteria do this)

Feeding Relationships

Energy flows through an ecosystem in one direction… from the sun or inorganic compounds to autotrophs (producers) and then to heterotrophs (consumers)

The relationships between producers & consumers connect organisms into feeding networks based on who eats whom

Trophic Levels

1st trophic level consists of

producers

2nd trophic level consists of herbivores

3rd trophic level is usually omnivores; can be carnivores

4th trophic level would be carnivores

Primary Productivity

Primary Productivity-rate at which organic matter is created by producers

More plants=more productivity

Which of the following ecosystems has the greatest primary productivity?

Analyze the Food Web

Find a food chain

State the producers

State organisms in the 2nd trophic level

Locate the omnivore

State organisms in the 4th tropic level

Ecological Pyramids

Ecological pyramids: a diagram that shows the relative amounts of energy or matter contained within each trophic level

Ecological Pyramid

Energy Pyramid-shows how much energy is produced at each level

Ecological Pyramids

Pyramid of Numbers-shows how many individuals are in each trophic level

Ecological Pyramids Pyramid of numbers-counts how

many animals are in each trophic level with in an ecosystem

A biology student counts the number of animals viewed on a Trialcam. In the forest, the camera photographed:

Grizzly bears

Deer

Rabbits

Sparrows

Squirrels

Based on the models, which of the animals would you expect to get most abundant in the forest? Why?

Energy Pyramid

Only 10% of the energy that is stored in one trophic level is passed on to the next level

Rest of the energy is used by organisms for life processes such as respiration, movement, and reproduction, or loss as heat

The more levels that exist between

a producer and a top level consumer,

the less energy that remains from

the original amount

How do Ecosystems Change Over Time?

If a major disruption strikes a community, such as the wipe out of many organisms, the ecosystem reacts in such a way that it is restored to equilibrium

Return to original state

Succession

Succession is the regular progression of species replacement

Primary succession – succession that occurs where life has not existed before

Secondary succession – succession in areas where there has been previous growth

Initial conditions and chance play roles in the process of succession

No two successions are alike

Primary Succession

New Organisms form on bare rock

First organisms to live in habitat are pioneer organisms (lichens)

Climax community-mature ecosystem at the end of succession

Primary succession happens after

Volcanic lava flow cools and forms rock

Glaciers retreat and expose rock

Secondary Succession

sequence of community changes that

takes place when a community is

disrupted by natural disaster or human

actions – takes place on existing soil

• Occurs after: A fire in a forest, A

farmer plows his field

Pond Succession

Ecosystem Resiliency

Resilience-ability to recover or adjust easily to change or misfortune without major affects

Predation

reduces effects of competition

Keystone Species – most influential species, regardless of population; removal causes serious disturbances of food web

Biodiversity –number of different species in ecosystem

Communities with greater diversity can recover quicker from a major disturbance like a drought

Cycle of Matter Reading Packet

HS-LS2-3

Construct and revise an explanation based on evidence for the cycling of matter and flow of energy in aerobic and anaerobic conditions.

Populations 5.1

HS-LS2-2

Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales.

5.1 Populations

Population –group of organisms of same species that live in a specific geographical area and interbreed

Populations tend to grow because individuals multiply by producing offspring

Eventually, limited resources in an environment limit growth

Demography – statistical study of all populations

Study the composition and population to predict how size of population will change over time

Three Key Features of Populations

1.Geographic Distribution

The way they are arranged in a population

Three main patterns.. Random, even, clumped.

Three Key Features of Populations

2. Population density-# of individuals that live in a given area

If individuals of population are few and are spaced widely apart, they may not come into contact – no reproduction

Three Key Features of Populations

3.Population Growth-# of individuals in a population

Number of births

Number of deaths

Emigration (out) & Immigration (in)

Growth= Birth Rate-Death Rate

Births=Deaths = No Gowth

Exponential Growth

- Positive Growth rate = population increase Negative Growth rate = decrease Exponential Growth –reproduce at a constant rate. Occurs under ideal conditions (no limits)

- Exponential growth- occurs when individuals in a population reproduce at a constant rate (J-shaped)

-If a population has abundant space and food, and is protected from predators and disease, then organisms in that population will multiply and the population size will increase.

Logistic Growth

Populations do not usually grow unchecked

Limited by predators, disease, and the availability of resources

Carrying capacity – the population size that an environment can sustain, support at a given time. (S-shaped)

As resources become less available, the growth of populations slows or stops

When birthrate decreases, death rate increases, or when they are

the same

Limits to Growth

Factors that affect population growth

Density Dependent Factors – variables affected by number of organisms in area (depends on size of population)

Rate at which they become depleted depends on the population density

Greater the density, will faster factors are depleated (and vice versa)

Examples: nesting sites, as adult birds increase, there not enough nesting sites, so may birds do not have young, and population decreases

Limits to Growth

Density-independent factors – variables that affect population regardless of population size

Example: weather, floods, fires

Features affect Population Survival

Can affect ability of population to survive

Small populations most likely to become extinct

Random disturbances (fires, floods, etc.) endanger small populations

Interbreeding – reduces population’s fitness

Large population has better chance of survival

Community Interactions

Interactions in communities revolve around the relationships between organisms.

1.Predation-- an interaction in which one organism captures and feeds on another organism

Most animals are both predators and prey

Few species are not hunted by others

Killer whales are not hunted by any other animals

Coevolution – evolution of 2 or more species due to mutual influence

Predator-prey or parasite-host relations often develop adaptations in response to one another

Prey evolve to be faster runners

Community Interactions

2. Herbivory- Herbivores do not usually kill the plants they eat

Plants develop methods of defense against herbivores

3. Symbiosis “living together”

A. Mutualism both species benefit (bees and flowers)

B. Commensalism one member benefits and the other is no helped nor harmed (barnacles and whales, orchids and trees)

C. Parasitism-one species benefits and the other is harmed (tapeworms in digestive system)

Community Interactions

4. competition arises when two or more individuals (or populations) rely on the same limited resource. In doing so, both parties are impacted negatively

Stealing of food is called kleptoparasitism

Competitive exclusion-when one species eliminates another through competition

Similar species have similar needs, leads to competition

The organism that is slightly better at getting the resource will survive and reproduce successfully

The other either dies or moves to new ecosystem

Avoiding Competition

Niche- A species physical use (of space) of its habitat and its function within a community

Different from habitat- place organisms lives

Dividing Resources

However, some competitors do still live in the same place

This is possible because they divide the resources by possibly feeding in slightly different ways or in slightly different places

Example: Warbler