PopulationsPopulations

Definition of a PopulationDefinition of a Population A A populationpopulation is a is a

group of organisms group of organisms of the same species of the same species that breed together that breed together and inhabit a specific and inhabit a specific geographic area.geographic area.

Changes in Population sizeChanges in Population size The number of organisms in a The number of organisms in a

population population changeschanges with time with time Individuals are always being added or Individuals are always being added or

subtracted from a populationsubtracted from a population Pop’s increase by Pop’s increase by birth birth & immigration, & immigration,

decrease by death & emigrationdecrease by death & emigration

Population Growth EquationPopulation Growth Equation

(# births) – (# deaths) + (# immigrants) – (#emigrants)(# births) – (# deaths) + (# immigrants) – (#emigrants)

OROR

(# Births + # Immigrants) (# Births + # Immigrants) –– (# Deaths + # emigrants) (# Deaths + # emigrants)

Birth = NatalityBirth = Natality Death = Mortality Death = Mortality

Extremely fast growth in a population is called a Extremely fast growth in a population is called a Population Explosion. Population Explosion.

Reasons for a Reasons for a population explosion population explosion include:include:1.1. Plentiful food supplyPlentiful food supply

2.2. Abundant spaceAbundant space

3.3. Introduced (Alien) SpeciesIntroduced (Alien) Species

Introduced/Alien SpeciesIntroduced/Alien SpeciesAlien Species is the term for the Alien Species is the term for the

introduction of a foreign introduction of a foreign species to a new environment. species to a new environment. The Asian Carp is one The Asian Carp is one example.example.

Lack of predators & abundant Lack of predators & abundant food allows them to multiply food allows them to multiply easilyeasily

The Great Lakes have suffered The Great Lakes have suffered many problems because of the many problems because of the introduction of Zebra Mussels introduction of Zebra Mussels and other and other Alien SpeciesAlien Species

Population ExtinctionPopulation Extinction

A Population A Population ExtinctionExtinction occurs occurs when a greater number when a greater number of individuals leave a of individuals leave a population compared population compared to the number of to the number of individuals entering the individuals entering the population. population.

(Due to Death or (Due to Death or Emigration)Emigration)

Some Reasons for ExtinctionSome Reasons for Extinction Over-fishingOver-fishing PoachingPoaching Habitat LossHabitat Loss Climate ChangeClimate Change

Graphing Population GrowthGraphing Population Growth

Called population Called population growth curvesgrowth curves 2 Types: J-shaped and S-shaped2 Types: J-shaped and S-shaped

Exponential GrowthExponential Growth J-ShapedJ-Shaped - Population size increases slow at - Population size increases slow at

first, then rapidly increases first, then rapidly increases Organisms have a high reproductive rate – Organisms have a high reproductive rate –

reproduce at their full biotic potentialreproduce at their full biotic potential Often populations that grow this fast will Often populations that grow this fast will

eventually crash (organisms die off quickly) – eventually crash (organisms die off quickly) – occasionally the occasionally the population crashpopulation crash can lead to can lead to extinctionextinction

Usually population will continually increase and Usually population will continually increase and decrease in what is called a decrease in what is called a population cyclepopulation cycle

J- Shaped Growth CurveJ- Shaped Growth Curve

Population CyclesPopulation Cycles

Sketch these:

Biotic PotentialBiotic Potential is the maximum number of offspring that can is the maximum number of offspring that can

be reproduced in a given time frame, if be reproduced in a given time frame, if rresources were unlimited.esources were unlimited.

For example, human females could For example, human females could theoretically produce 1 child every 9 months theoretically produce 1 child every 9 months between the ages of approximately 12 and between the ages of approximately 12 and 45.45.

Organisms do Organisms do not not usually reproduce at their usually reproduce at their full biotic potential due to many different full biotic potential due to many different environmental factors (resources are limited).environmental factors (resources are limited).

Sigmoidal Growth Sigmoidal Growth (S-Shaped)(S-Shaped) Most populations grow in this fashionMost populations grow in this fashion Population growth is fast at first but Population growth is fast at first but

then slows down as the population then slows down as the population becomes largerbecomes larger

The point at which population growth The point at which population growth levels out or becomes steady is when levels out or becomes steady is when the number of births=deaths and the number of births=deaths and immigrants=emigrantsimmigrants=emigrants

S- Shaped Growth CurveS- Shaped Growth Curve

Carrying Capacity

Carrying CapacityCarrying Capacity

is the maximum number of organisms is the maximum number of organisms that an environment can support that an environment can support

Biotic Potential VideoBiotic Potential Video

http://www.youtube.com/watch?v=BSVbdaubxxg&safe=active

Populations Biotic Potential 2:58Populations Biotic Potential 2:58

Limiting FactorsLimiting FactorsLimiting Factors Limiting Factors are are factors that prevent a factors that prevent a population from growing population from growing larger. Also called larger. Also called Environmental Resistance.Environmental Resistance.

There are 2 main types: There are 2 main types:

density-dependent density-dependent factors factors

density-independent density-independent factorsfactors..

Population DensityPopulation Density Population size - the # of organisms Population size - the # of organisms

occupying a certain amount of space. occupying a certain amount of space.

Density Independent FactorsDensity Independent Factors

Regardless of how many organisms are in a Regardless of how many organisms are in a population, population, Density Independent Factors Density Independent Factors can limit population growth can limit population growth

These factors can affect future population sizeThese factors can affect future population size

(Deforestation)

Density Dependant FactorsDensity Dependant Factors1.1. PredationPredation

2.2. CompetitionCompetition

3.3. Disease (Plague, Flu, Disease (Plague, Flu, Rabies,etc..)Rabies,etc..)

4.4. ParasitismParasitism

5.5. Resources (food, Resources (food, water, shelter, etc..)water, shelter, etc..)

AssignmentAssignment

Worksheets on pages 20 - 28Worksheets on pages 20 - 28

Growing Bacteria P. 20Growing Bacteria P. 20

Carrying Capacity Page 21Carrying Capacity Page 21

1. 1. The number is increasing so rapidly in area A The number is increasing so rapidly in area A because there are favorable conditions for because there are favorable conditions for pollination…lots of male and female trees close pollination…lots of male and female trees close together, good weather, lots of water and sunshine, together, good weather, lots of water and sunshine, lots of insect pollinators…lots of insect pollinators…

2. Fluctuations in section C are due to slight 2. Fluctuations in section C are due to slight increases and decreases in population number due increases and decreases in population number due to DD factors that limit growthto DD factors that limit growth

3. B represents the Carrying Capacity of the area for 3. B represents the Carrying Capacity of the area for Jack PinesJack Pines

4. The average growth rate (net) in C is Zero (0)4. The average growth rate (net) in C is Zero (0)

55. . Growth is slow at first, while numbers that can breed are Growth is slow at first, while numbers that can breed are low. Next there is a period of rapid population growth low. Next there is a period of rapid population growth where many trees are reproducing at a very fast rate. where many trees are reproducing at a very fast rate. Finally, when the population reaches the carrying capacity, Finally, when the population reaches the carrying capacity, the reproductive rate slows again such that the net growth the reproductive rate slows again such that the net growth = 0= 0

6. The numbers of trees in the area would decrease . The 6. The numbers of trees in the area would decrease . The graph would curve downwards in a “crash”. After a period graph would curve downwards in a “crash”. After a period of adjustment, the numbers will again begin to increase of adjustment, the numbers will again begin to increase and the graph will turn to J shaped again.and the graph will turn to J shaped again.

7. Numbers of trees would decrease as the area is logged, 7. Numbers of trees would decrease as the area is logged, but at a slower rate than if a forest fire wiped them out all but at a slower rate than if a forest fire wiped them out all at onceat once

1.

2. Large increase in deer could be 2. Large increase in deer could be due to them having lots of food, mild due to them having lots of food, mild weather and low numbers of weather and low numbers of predators like wolves.predators like wolves.

3. The deer population may have 3. The deer population may have decreased because of high numbers decreased because of high numbers of wolves, high numbers of deer of wolves, high numbers of deer competing for the same resources, competing for the same resources, deer hunting season, harsh weather, deer hunting season, harsh weather, natural disaster (flood etc)natural disaster (flood etc)

4. The wolf population was high 4. The wolf population was high because there were lots of deer for because there were lots of deer for food. food.

5. The relationship between wolves 5. The relationship between wolves and deer is related/correlated. When and deer is related/correlated. When deer increase in number, so do deer increase in number, so do wolves, and visa versa.wolves, and visa versa.

6. By extrapolation/estimated, there 6. By extrapolation/estimated, there would be approx. 5000 deer and 33 would be approx. 5000 deer and 33 wolveswolves

7. Yes or No. Yes, if there are too 7. Yes or No. Yes, if there are too many wolves, they could prey on many wolves, they could prey on domestic animals like cattle. No, they domestic animals like cattle. No, they are following the natural course of are following the natural course of their population cycle.their population cycle.

8. 8. • A. decreaseA. decrease• B. increaseB. increase• C. decreaseC. decrease• D. decreaseD. decrease• E. increaseE. increase

9. Hunting and trapping limits are 9. Hunting and trapping limits are calculated based on how many calculated based on how many animals can be killed without putting animals can be killed without putting the population in danger of crashing to the population in danger of crashing to low numbers or extinction. So when low numbers or extinction. So when deer populations are high, then deer populations are high, then hunting limits can also be high.hunting limits can also be high.

Limiting Factors p. 25/26Limiting Factors p. 25/26 1. DD – The larger the population, 1. DD – The larger the population,

the larger the impact of the factorthe larger the impact of the factor DI – the factor operates to its full DI – the factor operates to its full

extent no matter how big the extent no matter how big the population ispopulation is

2.a. DD (competition)2.a. DD (competition)

b. DD (predation)b. DD (predation)

c. DI (weather)c. DI (weather)

D. DI (natural disaster)D. DI (natural disaster)

E. DD (stress, disease, competition, lack of E. DD (stress, disease, competition, lack of food,water, shelter, jobs)food,water, shelter, jobs)

F. DD (predation)F. DD (predation)

G. DI (natural disaster)G. DI (natural disaster)

H. DD (overcrowding – lack of….)H. DD (overcrowding – lack of….)

I. DD (overcrowding - disease)I. DD (overcrowding - disease)

J. DI (severe weather)J. DI (severe weather)

K. DD (no predators)K. DD (no predators)

L. DD (competition)L. DD (competition)

M. DI (severe weather)M. DI (severe weather)

1. December = 21. December = 2

2. January = 9002. January = 900

3. 400 0003. 400 000

4. 1 800 000 0004. 1 800 000 000

5. At first the population needs time to 5. At first the population needs time to adjust. There are only a few males and adjust. There are only a few males and females to mate in the beginning and females to mate in the beginning and many more later on.many more later on.

6. Things flies compete with are dogs, 6. Things flies compete with are dogs, humans, other insects, bacteriahumans, other insects, bacteria

7. Factors that changed when the 7. Factors that changed when the window was opened include window was opened include temperature, other insects came in, temperature, other insects came in, some flies flew awaysome flies flew away

8. DD factors: food, water, space, 8. DD factors: food, water, space, predators, disease, overcrowding, predators, disease, overcrowding, stressstress

9. DI factor: Temperature9. DI factor: Temperature

10. Drought is DI. It causes a reduction 10. Drought is DI. It causes a reduction in food supply regardless of how many in food supply regardless of how many individuals are in the populationindividuals are in the population

11. Competition is DD. The more 11. Competition is DD. The more individuals, the more competition for individuals, the more competition for food, water, space, etc.food, water, space, etc.

Populations video p. 29/30Populations video p. 29/30

23 minutes

Eyes of Nye Video p. 29/30Eyes of Nye Video p. 29/30

1. world population reached 6 billion1. world population reached 6 billion 2. 5 billion2. 5 billion 3. 9 billion3. 9 billion 4. longer life expectancy, more food, 4. longer life expectancy, more food,

better food, better medicinebetter food, better medicine 5. 1505. 150 6. population explosion/exponential 6. population explosion/exponential

growth/J-shaped growthgrowth/J-shaped growth

7. The World’s Fair was in 1965. World 7. The World’s Fair was in 1965. World Pop was 3 billion. It took 34 years for the Pop was 3 billion. It took 34 years for the world pop to double (1999-1965)world pop to double (1999-1965)

8. In order to help reduce the growth 8. In order to help reduce the growth rate, the UN decided that women should rate, the UN decided that women should be entitled to be in control of the size of be entitled to be in control of the size of their family. That meant that women their family. That meant that women needed to receive higher educationneeded to receive higher education

9. Nearly ½ of the people on our planet are under 9. Nearly ½ of the people on our planet are under the age of 25the age of 25

10. A woman is fertile for approx. 30 years. 10. A woman is fertile for approx. 30 years. Because there are so many young females on Because there are so many young females on Earth right now, there lies a possibility of massive Earth right now, there lies a possibility of massive population growthpopulation growth

11. China passed the One Child/family law. Yes the 11. China passed the One Child/family law. Yes the law worked and population growth slowed down. law worked and population growth slowed down. Population size has decreased by over 200 million.Population size has decreased by over 200 million.

12. China, India, US12. China, India, US

13. The 2.1 replacement rate means that 13. The 2.1 replacement rate means that most couples are having 2 kids while some most couples are having 2 kids while some arent having any. This is important arent having any. This is important because it has resulted in a net population because it has resulted in a net population growth is close to zero, which means births growth is close to zero, which means births are almost equal to deaths. The US pop is are almost equal to deaths. The US pop is still growing because of immigration.still growing because of immigration.

14. Just 5% of the worlds population lives in the US 14. Just 5% of the worlds population lives in the US yet US citizens consume 30% of the worlds yet US citizens consume 30% of the worlds resourcesresources

15. Three planet Earth’s15. Three planet Earth’s

16. Bill suggests that reducing the growth rate to 16. Bill suggests that reducing the growth rate to 1.7. In other words, deaths need to be higher than 1.7. In other words, deaths need to be higher than births so that overall population size will decrease. births so that overall population size will decrease. (Replacement rate is 2 – 2 kids for 2 parents)(Replacement rate is 2 – 2 kids for 2 parents)

Bart vs. Australia video p. 34Bart vs. Australia video p. 34

1. Can’t bring foreign plants and animals 1. Can’t bring foreign plants and animals into a country they didn’t live in before into a country they didn’t live in before because these “alien” species could because these “alien” species could multiply out of control and destroy the multiply out of control and destroy the native environment.native environment.

2. Bullfrogs2. Bullfrogs

3. The number of frogs increased 3. The number of frogs increased exponentially – population explosionexponentially – population explosion

4. The introduced frogs ate all the crops4. The introduced frogs ate all the crops

5. Lisa said that’s what happens when you 5. Lisa said that’s what happens when you introduce a foreign species into an introduce a foreign species into an ecosystem that can’t handle themecosystem that can’t handle them

6. Koala’s only eat Eucalyptus trees which 6. Koala’s only eat Eucalyptus trees which we don’t have here so probably they we don’t have here so probably they wouldn’t survivewouldn’t survive

7. Realistic concept. It actually happens in 7. Realistic concept. It actually happens in real lifereal life

Toxic Toads Worksheet p 35/36Toxic Toads Worksheet p 35/361. Cane Toads were introduced to Australia 1. Cane Toads were introduced to Australia from Hawaii in 1935from Hawaii in 1935

2. Although not specified in the article, it was 2. Although not specified in the article, it was the Bureau of Sugar Experiment Stations, an the Bureau of Sugar Experiment Stations, an Australian government research institutionAustralian government research institution

3. The toads were introduced in an effort to 3. The toads were introduced in an effort to control the spread of beetles that were control the spread of beetles that were destroying sugar cane cropsdestroying sugar cane crops

4. The rate of invasion was 30 miles/year4. The rate of invasion was 30 miles/year

5. Three reasons for the ever increasing 5. Three reasons for the ever increasing numbers of toads include having lots of numbers of toads include having lots of food, no predators, and having a high food, no predators, and having a high reproductive ratereproductive rate

6. When an Alien species is first 6. When an Alien species is first introduced, it multiplies very slowly as it introduced, it multiplies very slowly as it takes time to adapt to the new takes time to adapt to the new environmentenvironment

7. An ecological nightmare may occur if 7. An ecological nightmare may occur if the toads outcompete native species to the toads outcompete native species to the point of their extinction. That will lead the point of their extinction. That will lead to a domino effect of other species to a domino effect of other species extinctions. The toads will be the extinctions. The toads will be the dominant species and multiply out of dominant species and multiply out of control until their population crashes too.control until their population crashes too.

Video Video Worksheet Worksheet

p. 33p. 33

1. Co-operation can be seen as:1. Co-operation can be seen as:

• Males and females share the task of Males and females share the task of incubating the eggincubating the egg

• Males huddle together and rotate positions Males huddle together and rotate positions during winter storms to keep warmduring winter storms to keep warm

• Penguins are well adapted to their Penguins are well adapted to their environment and its harsh weather environment and its harsh weather conditions conditions

2. Summer – penguins spread out along 2. Summer – penguins spread out along the seashorethe seashore

Spring – penguin population is most Spring – penguin population is most dense at the breeding site, after the dense at the breeding site, after the females return and chicks are bornfemales return and chicks are born

Fall – penguin density increases along Fall – penguin density increases along seashore as they prepare to marchseashore as they prepare to march

Winter – population high at breeding siteWinter – population high at breeding site

Carrying capacity is the total number of penguins Carrying capacity is the total number of penguins that can be supported in the specified area. that can be supported in the specified area.

FemalesFemales lose 1/3 of their body mass when they lose 1/3 of their body mass when they produce an egg and must return to the sea immediately produce an egg and must return to the sea immediately after laying an egg in order to eat and surviveafter laying an egg in order to eat and survive

MalesMales remain at the breeding site in order to incubate remain at the breeding site in order to incubate the egg. They go without food and must endure the the egg. They go without food and must endure the harshest of weather for longer periods of time compared harshest of weather for longer periods of time compared to females and thus more male penguins dieto females and thus more male penguins die

4. DD factors:4. DD factors:• Competition for matesCompetition for mates• Predation by leopard seals and seagullsPredation by leopard seals and seagulls• Lack of food/starvation (males don’t eat for 3 Lack of food/starvation (males don’t eat for 3

months)months)

5. DI factors5. DI factors• Harsh weatherHarsh weather• Climate Change – ice thickness is decreasing Climate Change – ice thickness is decreasing

6. 6. InterInterspecific Competitionspecific Competition• (Between different species)(Between different species)• Seals, fish, other birds (all feed on the Seals, fish, other birds (all feed on the

same kind of fish that penguins eat)same kind of fish that penguins eat)

7.7. IntraIntraspecific Competition specific Competition • (between penguins – the same species)(between penguins – the same species)• Penguins compete with each other for Penguins compete with each other for

things like food, water, territory, mates, things like food, water, territory, mates,