AP Bio: Monday, 12.20.10Unit 7: Ecology

Homework: Decide which biome you will do for your project Finish reading and taking notes on Chapter 54

Do Now: How do you define ecology?

Goals for Today: Describe the differences between the way that

energy and nutrients move through ecosystems Define and explain primary productivity and explain

what factors influence it Agenda:

Introduce Biome Project Lecture: Intro to Ecology

Ecology - • The study of interactions between organisms

and their environment– other organisms – abiotic factors

Big Themes of this Unit:• Energy flow – in one direction, and inefficient

transfer• Nutrient cycling (my waste = your food)• Interdependence (within populations, and

between species [food webs])• Human impacts on ecosystems

Ecosystems Ecology

Ecosystem – all the organisms and abiotic factors in a given area

Ex:• a hardwood forest ecosystem in central MA• a freshwater pond

Ecosystem components interact through transfers of energy and nutrients.

What do the following images show concerning

energy flow vs. nutrient cycles?

Energy Flow:• One-way series of energy

transfers:Solar energy

Chemical energy stored in organisms

Heat energy• Inefficient transfer at each

step (1% - 20% transferred; the rest is used for metabolism & ultimately lost as heat)

• Energy can’t be recaptured or used again once it’s lost as heat

Nutrient Cycling:• Cyclic transfer of nutrients

between biotic and abiotic components

Soil/water Producers

DecomposersConsumers

• All atoms are continually recycled – no net inputs or outputs in the biosphere

Energy Transfer is Inefficient…

Energy Pyramid:

1% of solar energy captured by primary producers

~ 10% of energy transfer between each trophic level

Foundation of the Food Web: Primary Productivity

PP = the amount of light energy converted to chemical energy (organic compounds i.e. sugars) by producers (autotrophs) in a given time periodCan be thought of as…– The amount of photosynthesis done– The amount of carbon fixed

Gross PP = total amount

Net PP = total amount minus the energy used for cell respiration by the producers themselvesNPP = GPP – Resp.

Global NPP: What influences it?

Primary Productivity inAquatic Ecosystems

• Limited by availability of…– Light– Nutrients

• How do we measure aquatic PP? (this week’s lab)

6C02 + 6H20 C6H12O6 + 602

• Oxygen produced during photosynthesis dissolves in water – DO2

• Measuring DO gives a measure of PP

AP Bio: Tuesday, 12.21.10Nutrient Cycles

Homework: Work on your biome project

Do Now: What powers the water cycle?

Goals for Today: Explain how water, carbon, and nitrogen cycle

through ecosystemsAgenda:

Hand back tests Lecture/Discussion of Notes: Nutrient Cycles Practice MCQs

Nutrient CyclesWater Cycle: Carbon Cycle:

Nutrient CyclesNitrogen Cycle:

How Does Nutrient Availability Affect Aquatic Ecosystems?

How Does Nutrient Availability Affect Aquatic Ecosystems?

• Eutrophication – process in which aquatic ecosystems become (overly) full

of nutrients like N, K, and P• Allows algae to grow (too) prolifically algae bloom• Algae blocks sunlight for other plants• Algae die and decomposer bacteria eat them and

flourish• Bacteria use up all the DO2

• None left for fish and other organisms they die ocean dead zones

Interactions between Organisms and Nutrients: The Hubbard Brook Experiment

• Cut down all trees, measure nutrients in run-off water

Conclusions?– Trees help hold nutrients in the ecosystem!

Interactions between Organisms and Nutrients: The Hubbard Brook Experiment

AP Bio: Wednesday, 12.22.10Population & Community Ecology

Homework: Work on your biome project

Do Now: Get a laptop

Goals for Today: Identify the key characteristics and major species of your

biome or ecosystem Apply ecological concepts to a particular biome or ecosystem Describe the factors that influence population growth in a

species Identify types of interactions between species in a community

Agenda: Period 1: Work on Biome Project Period 2: Lecture – Population & Community Ecology

Population Ecology

“Life history strategies” - based on reproductive strategies

Two extremes:

The Fast and the Furious/ Slow and Steady

The Young and the Restless

Survivorship Curves

Fraction of Survivors

Max. Life Span

Population Growth:

• Determined by birth rate and death rate• Density-dependent factors limit population growth

– Resources (food, nutrients, light, habitat/territory)– Disease– Aggressive behavior

• Density-independent populations – birth and death rates don’t change with increasing population size

Two Models for Population Growth

(1) ExponentialGrowth

dN/dt = rN

• r-selected populations (r = growth rate; this determines pop. growth)

(2) Logistic Growth

dN/dt = rN([K-N]/K

K = Carrying Capacity -

The maximum population size that an ecosystem can sustainably support over time

K-selected populations – carrying capacity determines population size

Human Population Growth

• Exponential or logistic?• What is Earth’s carrying capacity for

humans?

Community Ecology(interactions between species)

• Niche – – The particular role that a species plays in its

community• Food, predators, micro-habitat, active time of day

• Interactions between species can be positive, neutral, or negative

+/+ +/n +/- -/-

• Competition - – Species compete for food, water, light,

habitat– Occurs when niches overlap– Introduced / “Exotic Invasive” Species –

often outcompete native species

AP Bio: Thursday, 12.23.10Ecological Succession

Homework: Work on your biome project Have a great vacation!

Do Now: If the clear-cut area shown above were left

alone (no more trees cut) for 20 years, how do you think the community of species would change over time?

Why? What do you think the phrase “ecological

succession” means?

AP Bio: Thursday, 12.23.10Ecological Succession

Goal for Today: Predict how and why ecological communities

change after a disturbance

Agenda: Partner Practice-Quiz: Free Response

Question Grade question and discuss succession Finish up lecture from yesterday

(Sorry, we couldn’t get computers for today… )

AP Bio: Monday, 1.3.11Welcome Back & Happy New Year!

Homework: Lab 12 Pre-Lab (#1-5) Do Now: (please write this in your

notebook)(1) Describe one cool thing you did or learned over

the break.(2) Do you want to present your biome project to the

whole class?(3) What is primary productivity? (check your notes

for a reminder) Goals for Today:

Define and explain primary productivity Identify key characteristics of major biomes

Foundation of the Food Web: Primary Productivity

PP = the amount of light energy converted to chemical energy (organic compounds i.e. sugars) by producers (autotrophs) in a given time periodCan be thought of as…– The amount of photosynthesis done– The amount of carbon fixed

Gross PP = total amount

Net PP = total amount minus the energy used for cell respiration by the producers themselvesNPP = GPP – Resp.

Global NPP: What influences it?

Primary Productivity inAquatic Ecosystems

• Limited by availability of…– Light– Nutrients

• How do we measure aquatic PP? (this week’s lab)

6C02 + 6H20 C6H12O6 + 602

• Oxygen produced during photosynthesis dissolves in water – DO2

• Measuring DO gives a measure of PP

AP Bio: Monday, 1.3.11Biome Projects

Homework: Lab 12 Pre-Lab (#1-5)

Goals for Today: Define and explain primary productivity Identify key characteristics of major biomes

AP Bio: Tuesday, 1.4.11Dissolved Oxygen Lab

Homework: Lab 12 Part A – Graph and analysis

Do Now: Take out Lab 12

Goals for Today: Experimentally determine how temperature affects

the dissolved oxygen content of water

Agenda: Lab!

AP Bio: Tuesday, 1.4.11Lab 12 Part B: Primary Productivity

Homework: None Do Now:

Take out Lab 12 and turn to page 8 Goals for Today:

Set up an experiment to determine how water depth (aka % light) affects primary productivity of aquatic algae

Agenda: Review Lab 12 Part A Biome Presentation Pre-Lab for Part B Set up Part B Biome browsing

• Predation– One species eats another– Predator adaptations– Prey adaptations

• Cryptic coloration• Toxins and warning coloration• Mimicry

• Predator-prey population cycles

Keystone Species

Biologicalmagnification