Chapters 3-5Chapters 3-5Communities, Communities,

Population Biology, Biological Population Biology, Biological Diversity & ConservationDiversity & Conservation

Big Idea: How much can ecosystems Big Idea: How much can ecosystems handle before we screw them up handle before we screw them up

permanently? permanently?

Living in the CommunityLiving in the Community Community – collection of Community – collection of

interacting populationsinteracting populations Limiting Factors – Limiting Factors –

environmental factors that environmental factors that affect an organism’s ability affect an organism’s ability to survive in its environmentto survive in its environment Can be living: food Can be living: food

availability, predatorsavailability, predators Can be non-living: Can be non-living:

temperature, water, sunlighttemperature, water, sunlight Can affect a population Can affect a population

directly or indirectlydirectly or indirectly For instance, food availability For instance, food availability

will affect a herbivore and the will affect a herbivore and the carnivore that eats the herbivorecarnivore that eats the herbivore

Ranges of ToleranceRanges of Tolerance Tolerance – the ability of an organism to withstand Tolerance – the ability of an organism to withstand

fluctuations in biotic and abiotic environmental fluctuations in biotic and abiotic environmental factorsfactors Each organism has a specific range that it can survive in for Each organism has a specific range that it can survive in for

a specific factora specific factor Ex: catfish can tolerate warm water with little oxygen, Ex: catfish can tolerate warm water with little oxygen,

while bass or trout cannotwhile bass or trout cannot

Organisms Absent

Zone of Intolerance

OrganismsInfrequent

Zone of Physiological

stress

Greatest Number of Organisms

Optimum Range

OrganismsInfrequent

Zone of Physiological

Stress

Organisms Absent

Zone ofIntolerance

Pop

ulat

ion

Range of ToleranceLow High

Pg. 66 of book

SuccessionSuccession Let’s say you no longer cut your lawn. What Let’s say you no longer cut your lawn. What

would happen with sufficient water?would happen with sufficient water?

1. The grass gets taller; weeds start to grow. The 1. The grass gets taller; weeds start to grow. The area resembles a meadow.area resembles a meadow.

2. Later, bushes grow, trees appear and different 2. Later, bushes grow, trees appear and different animals enter the area to live.animals enter the area to live.

3. The bushes and trees change the environment; 3. The bushes and trees change the environment; less light reaches the ground. The grass slowly less light reaches the ground. The grass slowly disappears.disappears.

4. Thirty years later, the area is a forest. 4. Thirty years later, the area is a forest.

SuccessionSuccession The orderly, natural changes and species The orderly, natural changes and species

replacements that take place in the replacements that take place in the communities of an ecosystemcommunities of an ecosystem

Primary Succession – the colonization of Primary Succession – the colonization of new sites by communities of organismsnew sites by communities of organisms

Pioneer Species – the first species in an areaPioneer Species – the first species in an area Ex: Lichen (a combination of fungus and algae) Ex: Lichen (a combination of fungus and algae)

grows readily after a volcanic eruptiongrows readily after a volcanic eruption Lichens break up rock slowly and help soil Lichens break up rock slowly and help soil

accumulateaccumulate Slowly, more things are able to live in the Slowly, more things are able to live in the

environmentenvironment

Climax Community – mature community Climax Community – mature community that undergoes little or no changethat undergoes little or no change Ex: Deciduous forestEx: Deciduous forest

Secondary SuccessionSecondary Succession

The sequence of community changes The sequence of community changes that takes place after a community is that takes place after a community is disrupted by natural disasters or disrupted by natural disasters or human actionshuman actions Occurs on land that already has soilOccurs on land that already has soil The pioneer species will be different and The pioneer species will be different and

the community will climax in a shorter the community will climax in a shorter timetime

Example: Yellowstone burned in Example: Yellowstone burned in 19881988 Wildflowers came back first, then Wildflowers came back first, then

grasses, ferns and pine seedlingsgrasses, ferns and pine seedlings

BiomeBiome A biome is a large group of ecosystems that share A biome is a large group of ecosystems that share

the same type of climax communitythe same type of climax community There are terrestrial biomes (tundra, taiga, desert, There are terrestrial biomes (tundra, taiga, desert,

grassland, temperate forest, rain forest)grassland, temperate forest, rain forest) There are aquatic biomes (marine, estuaries, There are aquatic biomes (marine, estuaries,

freshwater) freshwater)

Review Review

What are the two kinds of limiting factors?What are the two kinds of limiting factors? What is a range of tolerance? Give an What is a range of tolerance? Give an

example. example. What is primary succession?What is primary succession? What is secondary succession?What is secondary succession? What is a biome?What is a biome? What is a pioneer species?What is a pioneer species?

Chapter 4 – Population BiologyChapter 4 – Population Biology

Population Growth – an Population Growth – an increase in the size of a increase in the size of a population over timepopulation over time

All populations start off All populations start off growing relatively growing relatively slowly (relative to their slowly (relative to their capacity to reproduce)capacity to reproduce)

If resources are not If resources are not limited, all populations limited, all populations will grow exponentially will grow exponentially (a “J” curve) (a “J” curve)

Exponential Growth

0

50

100

150

200

250

1 2 3 4 5 6 7 8 9 10

TimeNu

mbe

r

E. coli

Realistic Population GrowthRealistic Population Growth Resources are never unlimitedResources are never unlimited Populations will reach a carrying capacity – the Populations will reach a carrying capacity – the

number of organisms of one species that an number of organisms of one species that an environment can supportenvironment can support

Populations follow an S-shaped growth curvePopulations follow an S-shaped growth curve

---------------------------------------------------------------------------------------------------Carrying Capacity

Beginning Growth - Population slowly increases

Rapid Growth –

exponential growth

Leveling Off – competition, limited resources slow growth, limiting factors

Carrying Capacity – if population gets bigger, organisms die

Fluctuations – birth and death rates fluctuate with competition and resources

Pg. 94 of book

Patterns of Population GrowthPatterns of Population Growth Some organisms reach their Some organisms reach their

carrying capacity faster than carrying capacity faster than othersothers This is due to their This is due to their

reproductive patternsreproductive patterns Environmental ConditionsEnvironmental Conditions

Ideal rangesIdeal ranges In general, organisms that are In general, organisms that are

small and mature rapidly small and mature rapidly reach carrying capacity fasterreach carrying capacity faster Organisms that are large and Organisms that are large and

mature slowly, reach a mature slowly, reach a carrying capacity slowercarrying capacity slower

Environmental Limits to Environmental Limits to Population Growth Population Growth

Density-Dependent Limiting Factors have an Density-Dependent Limiting Factors have an increasing effect as the population increasesincreasing effect as the population increases Ex: disease, competition, parasites, foodEx: disease, competition, parasites, food Ex: How does predation effect population sizes?Ex: How does predation effect population sizes?

Density-Independent Limiting Factors affect Density-Independent Limiting Factors affect all populations, regardless of their densityall populations, regardless of their density Most are abiotic factors such as temperature, Most are abiotic factors such as temperature,

storms, flood, drought, habitat destructionstorms, flood, drought, habitat destruction

Density-Dependent Limiting FactorsDensity-Dependent Limiting Factors Competition – increases within species as population Competition – increases within species as population

gets too big. gets too big. Over food, water, territory, mates, etc.Over food, water, territory, mates, etc. Can you see this in a human population?Can you see this in a human population?

Density-Dependent Limiting FactorsDensity-Dependent Limiting Factors Crowding & Stress – as Crowding & Stress – as

populations increase in populations increase in size, individual animals size, individual animals begin to exhibit:begin to exhibit: AggressionAggression Decrease in parental Decrease in parental

carecare Decreased fertilityDecreased fertility Decreased Decreased

resistance to diseaseresistance to disease Can you see this in Can you see this in

a human a human population?population?

ReviewReview

1.1. What conditions must be met for exponential What conditions must be met for exponential growth?growth?

2.2. What pattern do populations follow in reality?What pattern do populations follow in reality?

3.3. What determines how fast a population reaches its What determines how fast a population reaches its carrying capacity?carrying capacity?

4.4. Give 3 density-independent limiting factors.Give 3 density-independent limiting factors.

5.5. How can crowding and stress limit a population? How can crowding and stress limit a population?

6.6. Describe the relationship between predators and Describe the relationship between predators and prey.prey.

Demographic TrendsDemographic Trends

Demography – the study of human population growth Demography – the study of human population growth characteristicscharacteristics i.e., growth rate, age structure, geographic distributioni.e., growth rate, age structure, geographic distribution

Humans reduce negative environmental effects on our Humans reduce negative environmental effects on our population population i.e., eliminating competitors, increasing food production, i.e., eliminating competitors, increasing food production,

controlling diseasescontrolling diseases Human Population (see pg. 100 in book)Human Population (see pg. 100 in book)

1 A.D. – around 1850 : slow growth1 A.D. – around 1850 : slow growth After 1850-present: exponential growth (J-curve)After 1850-present: exponential growth (J-curve)

Realistic Population GrowthRealistic Population Growth

Where are humans on this curve?Where are humans on this curve? What will eventually have to happen? What will eventually have to happen?

---------------------------------------------------------------------------------------------------Carrying Capacity

Beginning Growth - Population slowly increases

Rapid Growth –

exponential growth

Leveling Off – competition, limited resources slow growth

Carrying Capacity – if population gets bigger, organisms die

Fluctuations – birth and death rates fluctuate with competition and resources

Pg. 94 of book

Birth and Death RatesBirth and Death Rates Death Rate – the number of deaths per 1000 people in a given yearDeath Rate – the number of deaths per 1000 people in a given year

Affected by life expectancy, diseases in area, stress, etc. Affected by life expectancy, diseases in area, stress, etc. Difference in Africa and U.S.? Difference in Africa and U.S.?

Birth Rate – the number of live births per 1000 people people in a Birth Rate – the number of live births per 1000 people people in a given year. given year. Fertility rate is a large influence here Fertility rate is a large influence here Difference in Africa and U.S.? Difference in Africa and U.S.?

Birthrate (per Birthrate (per 1000)1000)

Death Rate (per Death Rate (per 1000)1000)

Fertility (per Fertility (per woman)woman)

Population Population Increase (percent)Increase (percent)

JordanJordan 38.838.8 5.55.5 3.33.3 3.33.3

UgandaUganda 50.850.8 21.821.8 7.17.1 2.92.9

ZimbabweZimbabwe 34.334.3 9.49.4 5.25.2 2.52.5

GermanyGermany 9.49.4 10.810.8 1.21.2 -1.5-1.5

ItalyItaly 9.49.4 9.79.7 1.21.2 -0.5-0.5

SwedenSweden 10.810.8 10.610.6 1.51.5 0.10.1

MexicoMexico 27.027.0 5.25.2 3.13.1 2.22.2

United StatesUnited States 14.814.8 8.88.8 2.02.0 0.60.6

Population Growth Rate (PGR)Population Growth Rate (PGR) Immigration – movement of individuals into a Immigration – movement of individuals into a

populationpopulation Emigration – movement from a populationEmigration – movement from a population Population Growth Rate = (Birthrate + Immigration Population Growth Rate = (Birthrate + Immigration

Rate) - (Death Rate + Emigration Rate) Rate) - (Death Rate + Emigration Rate) Or, for convenienceOr, for convenience

PGR = Birthrate - Death ratePGR = Birthrate - Death rate When birthrate equals death rate, the population isn’t When birthrate equals death rate, the population isn’t

growinggrowing As long as the PGR is positive, the population will As long as the PGR is positive, the population will

continue to growcontinue to grow

Doubling Time & Age StructureDoubling Time & Age Structure Doubling Time - the time needed for a population to Doubling Time - the time needed for a population to

double in sizedouble in size Doubling Time (in years) = 70/annual percent growth rateDoubling Time (in years) = 70/annual percent growth rate What is happening to the world doubling time?What is happening to the world doubling time?

Age structure refers to the proportions of a population Age structure refers to the proportions of a population that are at different age levelsthat are at different age levels If a population has many young members, it will mostly likely If a population has many young members, it will mostly likely

grow rapidlygrow rapidly If a population has equal numbers of ages, it is stableIf a population has equal numbers of ages, it is stable Look page 103 in bookLook page 103 in book

These demographics do not influence world population, These demographics do not influence world population, but do show movement from or to urban areas, countries, but do show movement from or to urban areas, countries, etc.etc.

Ecology and GrowthEcology and Growth Population needs differ throughout the Population needs differ throughout the

worldworld Some populations have competition Some populations have competition

for food, water, etc. for food, water, etc. Some population are more concerned Some population are more concerned

about the health of their citizensabout the health of their citizens When populations grow rapidly, there When populations grow rapidly, there

is often competition for resourcesis often competition for resources Lead to stress, contamination, etc. that Lead to stress, contamination, etc. that

lead to disease and affect stability of lead to disease and affect stability of populationspopulations

ReviewReview

1.1. How do humans “change the rules” in How do humans “change the rules” in demography?demography?

2.2. How do birth rates and death rates influence How do birth rates and death rates influence population growth?population growth?

3.3. How do you calculate population growth How do you calculate population growth rate?rate?

4.4. What is a population’s doubling time?What is a population’s doubling time?5.5. How do population needs differ around the How do population needs differ around the

world?world?

Biological DiversityBiological Diversity Biodiversity refers to the variety of life in an areaBiodiversity refers to the variety of life in an area

Most common measure is the number of species that live in a Most common measure is the number of species that live in a certain areacertain area

Terrestrial biodiversity tends to increase as you move towards the Terrestrial biodiversity tends to increase as you move towards the equator (or in isolated warm regions) equator (or in isolated warm regions) 2/3 of all land species on Earth are in tropical regions2/3 of all land species on Earth are in tropical regions

The size of the area also affects biodiversityThe size of the area also affects biodiversity Larger areas tend to be more diverse (unless other things Larger areas tend to be more diverse (unless other things

prevent or encourage life)prevent or encourage life)

Importance of BiodiversityImportance of Biodiversity Organisms are adapted to live together in a Organisms are adapted to live together in a

communitycommunity If you take one away, there are consequences to the restIf you take one away, there are consequences to the rest

Biodiversity brings stability to an ecosystemBiodiversity brings stability to an ecosystem More resources, interactions, etc.More resources, interactions, etc. When a population utilizes more than one resource, it will When a population utilizes more than one resource, it will

be ok if one of them disappearbe ok if one of them disappear Biodiversity is important to humansBiodiversity is important to humans

Oxygen to breath, remove COOxygen to breath, remove CO22

Diverse diet / Better crops (resistance)Diverse diet / Better crops (resistance) Building materialsBuilding materials Possible pharmaceuticalsPossible pharmaceuticals

Loss of BiodiversityLoss of Biodiversity Extinction – the disappearance of a species Extinction – the disappearance of a species

when the last of its members dieswhen the last of its members dies Since 1980, almost 40 species of plants and animals have Since 1980, almost 40 species of plants and animals have

gone extinct in the U.S.gone extinct in the U.S. Can be natural or human-causedCan be natural or human-caused

Threatened Species – when the population Threatened Species – when the population of a species begins declining rapidlyof a species begins declining rapidly In the US: sea otters, loggerhead turtles, bald eagleIn the US: sea otters, loggerhead turtles, bald eagle

Endangered Species – population numbers Endangered Species – population numbers so low that extinction is possibleso low that extinction is possible In the US: California Condor, Florida manateesIn the US: California Condor, Florida manatees

Threats to BiodiversityThreats to Biodiversity Habitat loss – the biggest threatHabitat loss – the biggest threat

Take away resources for lifeTake away resources for life Habitat fragmentation – separation of wilderness areas from Habitat fragmentation – separation of wilderness areas from

other wilderness areasother wilderness areas Roads – leads to less biodiversityRoads – leads to less biodiversity Animals that migrate or need large areas to huntAnimals that migrate or need large areas to hunt Climates can change (take away shade)Climates can change (take away shade) Edge Effect – the different conditions along the Edge Effect – the different conditions along the

boundaries of an ecosystemboundaries of an ecosystem

Threats to BiodiversityThreats to Biodiversity Habitat Degradation – the damage to a habitat by Habitat Degradation – the damage to a habitat by

pollutionpollution Air, Water, or Land Air, Water, or Land

Air PollutionAir Pollution Burning fossil fuels is the greatest source of air Burning fossil fuels is the greatest source of air

pollutionpollution Acid Precipitation – sulfur dioxide from burning Acid Precipitation – sulfur dioxide from burning

coal and nitrogen oxides from automobile exhausts coal and nitrogen oxides from automobile exhausts combine with water vapor combine with water vapor Leaches nutrients from the soilLeaches nutrients from the soil Damages plant tissuesDamages plant tissues Alters pH of lakes Alters pH of lakes

Ozone layer damage – CFC’s break down 0Ozone layer damage – CFC’s break down 033 Increased skin cancersIncreased skin cancers Possible cause for amphibian population decreasingPossible cause for amphibian population decreasing

Threats to BiodiversityThreats to Biodiversity Water PollutionWater Pollution Fertilizers and animal wastes carried by runoff Fertilizers and animal wastes carried by runoff

Causes algal blooms Causes algal blooms These algae die, decay and remove oxygen from the waterThese algae die, decay and remove oxygen from the water

Silt from erosion clogs gills, blocks sunlightSilt from erosion clogs gills, blocks sunlight Detergents, metals, industrial chemicals from runoffDetergents, metals, industrial chemicals from runoff Debris in oceans and lakesDebris in oceans and lakes

Threats to BiodiversityThreats to Biodiversity Land pollution Land pollution Trash – the average American produces about Trash – the average American produces about

1.8 kg of solid waste daily – 657 kg/yr 1.8 kg of solid waste daily – 657 kg/yr Destroy habitats and pollute areasDestroy habitats and pollute areas

Pesticides, etc. can also lead to habitat Pesticides, etc. can also lead to habitat degredationdegredation DDTDDT

Threats to BiodiversityThreats to Biodiversity

Introduction of ExoticsIntroduction of Exotics Exotic species – organisms that are Exotic species – organisms that are

not native to a particular areanot native to a particular area Can grow at an exponential rate Can grow at an exponential rate

due to a lack of competitors and a due to a lack of competitors and a lack of predatorslack of predators

Take over niches of native Take over niches of native species or replace the species or replace the species species

Sea lamprey in Great Sea lamprey in Great Lakes after Erie Canal Lakes after Erie Canal

Goats on Santa Catalina Goats on Santa Catalina Island Island

Section 1 ReviewSection 1 Review

What are two reasons for a species to become What are two reasons for a species to become threatened or endangered?threatened or endangered?

Explain how land that gets broken up can contribute Explain how land that gets broken up can contribute to loss of species diversity.to loss of species diversity.

What is an edge effect? Explain how changes in an What is an edge effect? Explain how changes in an ecosystem’s edges can affect organisms.ecosystem’s edges can affect organisms.

How can exotic species affect populations of native How can exotic species affect populations of native species?species?

Conservation BiologyConservation Biology Conservation BiologyConservation Biology is the study is the study

and implementation of methods to and implementation of methods to protect biodiversity. protect biodiversity. Natural resource conservation - Natural resource conservation -

natural resourcesnatural resources are those parts are those parts of the environment that of the environment that are useful or necessary are useful or necessary for living organisms. for living organisms.

Species conservation - Species conservation - protecting species from protecting species from extinction and preserving biodiversityextinction and preserving biodiversity

Legal Protection of SpeciesLegal Protection of Species 1973, the U.S. Endangered Species Act made it illegal 1973, the U.S. Endangered Species Act made it illegal

to harm any species on the endangered or threatened listto harm any species on the endangered or threatened list Illegal for federal agencies to fund Illegal for federal agencies to fund

any project that would harm these any project that would harm these speciesspecies

The Convention on International Trade in Endangered The Convention on International Trade in Endangered Species (CITES)Species (CITES) Established lists of species for which international trade is Established lists of species for which international trade is

prohibited or controlled prohibited or controlled Honored by 120 countries Honored by 120 countries

Preserving HabitatsPreserving Habitats One way is to create One way is to create

national parksnational parks First one in US was First one in US was

YellowstoneYellowstone Originally this was to Originally this was to

preserve the geologypreserve the geology Protects natural Protects natural

environments and environments and provides habitats provides habitats for many organisms for many organisms

Habitat CorridorsHabitat Corridors

Protected strips of land Protected strips of land that allow the migration that allow the migration of organisms from one of organisms from one wilderness to anotherwilderness to another Isolated populations Isolated populations

inbreed too muchinbreed too much

Sustainable UseSustainable Use

In National Parks, the land is managedIn National Parks, the land is managed This philosophy strives to enable people to use This philosophy strives to enable people to use

natural resources in ways that will benefit natural resources in ways that will benefit them and maintain the ecosystemthem and maintain the ecosystem Some grazingSome grazing Harvest fruitsHarvest fruits Hiking, camping, etc. Hiking, camping, etc.

Preservation ProgramsPreservation Programs Captive Breeding followed by Captive Breeding followed by

Reintroduction ProgramsReintroduction Programs Release organisms into Release organisms into

area where the species once area where the species once livedlived

Ex: black-footed ferretEx: black-footed ferret Ex: brown pelican after Ex: brown pelican after

DDTDDT Seed banks for threatened and Seed banks for threatened and

endangered plant speciesendangered plant species

Section 2 ReviewSection 2 Review

Describe the U.S. Endangered Species Act. Describe the U.S. Endangered Species Act. Why is it difficult to reintroduce species that Why is it difficult to reintroduce species that

have been captive bred?have been captive bred? What is sustainable use and how does it What is sustainable use and how does it

influence Utah? influence Utah?