AGENDA May 15 Objective: Explain the forces that affect population dynamics within an ecosystem. Objective: Explain the forces that affect population dynamics.

AGENDA May 15AGENDA May 15

Objective: Explain the forces that affect Objective: Explain the forces that affect population dynamics within an ecosystem.population dynamics within an ecosystem.

1. Biomes Homework1. Biomes Homework 2. Begin Chapter 5: Communities and 2. Begin Chapter 5: Communities and

PopulationsPopulations 3. Homework and Review3. Homework and Review

– Food Web ProjectsFood Web Projects– Study your NotesStudy your Notes

4. BIOLOGY EOC is almost here!4. BIOLOGY EOC is almost here!

Chapter 5: Chapter 5: Populations and Populations and

CommunitiesCommunities

Useful DefinitionsUseful Definitions

Population – Group of organisms that Population – Group of organisms that all belong to the same species and all belong to the same species and live in a specific area.live in a specific area.

Steady State – Growth rate is zeroSteady State – Growth rate is zero

Population remains Population remains stablestable

Exponential GrowthExponential Growth

Ideal Ideal conditions for conditions for growth and growth and reproduction. reproduction.

Rapid increase Rapid increase in a in a population.population.

Logistic Growth Page Logistic Growth Page 10341034

Most populations go through a number of Most populations go through a number of growth phases.growth phases.

Carrying Capacity - # of individuals that Carrying Capacity - # of individuals that can be supported in a given environment.can be supported in a given environment.

Factors that Control Factors that Control Population GrowthPopulation Growth

Density-Dependent Limiting FactorsDensity-Dependent Limiting Factors Affect large populations more strongly than Affect large populations more strongly than

small populationssmall populations

1. Competition – individuals compete1. Competition – individuals compete 2. Predation – Sources of food2. Predation – Sources of food 3. Parasitism – living off other organisms3. Parasitism – living off other organisms 4. Crowding and Stress – overpopulation 4. Crowding and Stress – overpopulation

leads to leads to limited limited resourcesresources

Predator/Prey RelationshipsPredator/Prey Relationships Almost every animal serves as a food source Almost every animal serves as a food source

for another one.for another one. These species have coexisted for many years.These species have coexisted for many years. Accustomed to each other’s strengths and Accustomed to each other’s strengths and weaknesses.weaknesses.

Defense vs.Defense vs. CounterdefenseCounterdefense

The Best Defense is a Good The Best Defense is a Good DefenseDefense

PreyPrey PredatorPredator

Shells, poisonous skin,Shells, poisonous skin, Stronger jaws, Stronger jaws, digestivedigestive

Barbs, CamouflageBarbs, Camouflage enzymes, keen enzymes, keen eyesight,eyesight,

venomvenom Natural Selection….Natural Selection…. Adaptations that allow individuals to best Adaptations that allow individuals to best

survive and reproduce in their natural survive and reproduce in their natural environments.environments.

Section 3: Interactions Section 3: Interactions Among CommunitiesAmong Communities

Populations within a Populations within a community interact withcommunity interact with

one another in many one another in many ways.ways.

Plants compete for water, Plants compete for water, nutrients, and sunlight.nutrients, and sunlight. Herbivores compete Herbivores compete for food and space.for food and space. Carnivores compete for Carnivores compete for

the the herbivores often with herbivores often with

more than one species more than one species targeting the same prey.targeting the same prey.

InteractionsInteractions

1. Commensalism: One 1. Commensalism: One organism benefits and the organism benefits and the other is unharmed.other is unharmed.

2. Mutualism: Two species live 2. Mutualism: Two species live

together that benefit both together that benefit both organisms.organisms.

Interactions between Interactions between EcosystemsEcosystems Consider a pond in a Consider a pond in a

forest.forest. The pond supports a The pond supports a

whole range of plant whole range of plant and animal life.and animal life.

Water enters the pond Water enters the pond from a nearby stream.from a nearby stream.

Water runoff feeds a Water runoff feeds a different stream or different stream or marsh.marsh.

Animals in the forest Animals in the forest rely on the pond for rely on the pond for food and water.food and water.

Even birds that travel Even birds that travel many miles benefit many miles benefit from this pond.from this pond.

AGENDA May 18AGENDA May 18

Objective: Provide evidence as to why Objective: Provide evidence as to why humans disrupt population dynamics.humans disrupt population dynamics.

1. Predator – Prey Graphing Skills1. Predator – Prey Graphing Skills 2. Chapter 6: Human Population Dynamics2. Chapter 6: Human Population Dynamics 3. Homework and Review3. Homework and Review

– Food Web ProjectsFood Web Projects– Study your NotesStudy your Notes

4. BIOLOGY EOC is almost here!4. BIOLOGY EOC is almost here!

Chapter 6: Humans in the Chapter 6: Humans in the BiosphereBiosphere Humans affect the Humans affect the

environments they environments they inhabit.inhabit.

Massive number of Massive number of trees cut down.trees cut down.

Destroyed plants that Destroyed plants that did not provide did not provide benefits.benefits.

Dangerous/Wild animals Dangerous/Wild animals were hunted and killed were hunted and killed to protect humans and to protect humans and domesticated animals.domesticated animals.

Logging around the world continues to threaten and destroy many native species of plants and animals.

Factors that Determine Factors that Determine Population Growth Population Growth

Humans create enormous Humans create enormous demands on the natural demands on the natural resources of planet Earth.resources of planet Earth.

Birthrate versus Birthrate versus DeathrateDeathrate

Earth’s population Earth’s population continues to increase continues to increase threatening to use up threatening to use up many of its natural many of its natural resources to meet the resources to meet the basic needs of life.basic needs of life.

Earth’s population will double in the next half century at the current rates.

1.High birthrate2.Low deathrate3.Longer life-span

Human Population Growth Human Population Growth CurveCurve

PollutionPollution Biodegradeable Biodegradeable

organic wastes such organic wastes such as sewage and food as sewage and food scraps can be broken scraps can be broken down into essential down into essential nutrientsnutrients

Nonbiodegradeable Nonbiodegradeable ones cannot be ones cannot be broken down through broken down through natural processes natural processes (glass, chemicals, (glass, chemicals, plastics.)plastics.)

Garbage dump site in Mexico City, Mexico.

PollutionPollution

Industrial chemicals, sewage waste, and Industrial chemicals, sewage waste, and the thermal pollution (burning of fossil the thermal pollution (burning of fossil fuels)fuels)

The Greenhouse Effect (Carbon dioxide)The Greenhouse Effect (Carbon dioxide)

Destruction of the Ozone Layer Destruction of the Ozone Layer (Chloroflurocarbons are now banned)(Chloroflurocarbons are now banned)

Extinction of Plant and Animal Species Extinction of Plant and Animal Species (Destruction of natural habitats)(Destruction of natural habitats)

Saving the EarthSaving the Earth Going GreenGoing Green Conservation of land.Conservation of land. Protecting oceans and other Protecting oceans and other

bodies of water.bodies of water. Using more biodegradeable Using more biodegradeable

products.products. Breeding endangered species Breeding endangered species

in safe environments.in safe environments. Banning hunting for sport.Banning hunting for sport.

Joining the PTHS Joining the PTHS ENVIRONMENTAL ENVIRONMENTAL CLUB!CLUB!