How can humans cause population decline in other species?

7 billion and growing

How can humans cause population decline in other species?

“As dead as a dodo”

humans Mauritius,

dogspigscatsrats

nests, forests

Four ways humans can cause population decline are:

• Habitat ……………………………… (e.g. endangered panda)• Introducing new ……………………… (e.g. extinction of dodo)• Over………….. (decline in rhinos)• ……………………… change (decline in polar bears)

How can humans cause population growth in other species?

How can humans cause population growth in other species?

Four ways humans cause population growth in other species:

Improve conditions ( )

Reduce pressure from predators ( )

Reduce competition ( )

Introduce animals to new areas ( )

Humans are k strategists.

Fish are r strategists.

Fish? Human?Long life vs short lifeSlower growth vs rapid growthMature late vs mature earlyMany small offspring vs few large offspringLittle parental care vs lots of parental careHigh investment in individual offspring vs little investment in individual offspringPredators vs preyLower trophic level vs higher trophic levelPioneers and colonisers vs later stages of successionPopulation may crash vs live close to carrying capacityAdapted to unstable environment vs adapted to stable environment

r strategists k strategists

flour beetles trees bacteria annual plants albatrosses humans

Which are r strategists?

Which are k strategists?

For one example of each explain why.

Survivorship curves: I II III

A: Almost all individuals survive for their potential lifespan and then die almost simultaneously

B: Most individuals die at a very young age but those that do survive are likely to survive for a very long time

Answer:

1. Which of the following is a characteristic of K-selected organisms?

A. They are typical of pioneer communities.

B. Usually a very high percentage of young die during the early part of their life cycle.

C. Sexual maturity is reached early in the lifespan.

D. They usually have a high degree of parental care of young.

Answer:

2. Which statement most correctly describes K-strategist organisms?

A. They reach adulthood quickly and have many young.

B. They reach adulthood slowly and have many young.

C. They reach adulthood quickly and have few young.

D. They reach adulthood slowly and have few young.

Answer:

3. Which of the following is characteristic of r-selected organisms?

A. They are typical of pioneer communities.

B. Usually a high proportion of the young survive to adulthood.

C. Sexual maturity is reached late in the lifespan.

D. They usually have a high degree of parental care of their young.

4. The graph below shows the number of individual organisms surviving from an initial cohort of 1000, plotted against time. (A cohort is a group of organisms in a population that are born or hatch at about the same time.) Which line on the graph is most likely to represent a K-strategist?

A. I

B. II

C. III

D. IV

Answer:

5. I species reproduce and disperse rapidly and unfavourable environmental conditions can cause such populations to II

Which of the following provides the correct words to be inserted in the sentence above?

Answer:

I II

A. r-strategist increase

B. K-strategist crash

C. K-strategist increase

D. r-strategist crash

Answer:

6. An r-strategist generally

A. gives considerable parental care to its offspring.

B. is small and short-lived.

C. lives in a stable environment.

D. produces small numbers of offspring.

Answer:

7. Which of the following is a typical characteristic of a K-strategist?

A. Little or no parental care and protection of offspring

B. Low ability to compete

C. Reproduce late in life

D. Reproduce and disperse rapidly when conditions are favourable

Answer:

8. Which statement about K-strategists is correct?A. They are less adaptable than r-strategists.B. They have high genetic diversity.C. They exhibit fast rates of evolution.D. They live in a rapidly changing environment.

Answer:

9. Oysters release millions of eggs each time they breed, but most of their offspring die before reaching adulthood.This is an example ofA. an r-strategist organism.B. an organism threatened by extinction.C. a K-strategist organism.D. an organism typical of a climax community.

10. Lines I, II and III are survivorship curves for three different populations in an ecosystem. Which row best describes the nature of

the three populations? Answer:

r-strategists K-strategists Intermediate strategists

A. III II IB. I III IIC. III I IID. I II III

Answers

12345678910

What factors are going to stop the human population from growing?

The world is fast-reaching its carrying capacity.

(the maximum number of organisms that an area or ecosystem can sustainable support over a long period of time)

Evaluate the use of models in population prediction

+ or –

Many factors affect birth rate

Many factors affect death rate

Hard to predict how these factors will change

Predictions are accurate within some range

Need something to use for planning purposes

What single factor affected the decline in China’s population growth rate?

These are called limiting factors

What factors will stop animal and plant populations from growing?

(1) is the maximum number of organisms that an area or ecosystem can sustainable support over a long period of time.

Every species has a (2) for any environmental factor.There is an (3) within which any species can thrive.Beyond this a species will suffer (4)Above and below the tolerance threshold is the (5) where the species will be (6)

Tolerance rangeRange of intolerance Optimum rangeStress AbsentCarrying capacity

Explain the concepts of limiting factors and carrying capacity in the context of population growth.

Malthus Boserup

Who was he? Who was she?

When did he live? When did she live?

What was his profession? What was her profession?

What did he predict? What did she predict?

What was his limiting factor? How did she think we would overcome this limiting factor?

List 10 ways we have been able to increase food supply since Malthus’s time.

What did her studies show about change in farming techniques?

Describe and explain S- and J- population curves

Label the s curve and the j curve.

What are the stages in the typical s curve?

DENSITY-DEPENDENT AND DENSITY-INDEPENDENT FACTORS

These are factors that control the population size.

density dependent? density-independent?

density dependent? density-independent?

disease

tsunamis parasitism volcanic eruptionsnegative positive density dependent birth death density-independent biotic abiotic

Some limiting factors are related to how dense the population is. Some aren’t.…………………………………………………….. factors will control a population size if there is a high population density.They lower the …………………….. rate or raise the ……………………….. rate as the population grows in size. Density dependent factors cause ……………………………………. feedback to occur e.g.……………………………………………….. will control a population size whether there is a high population density or not.Density independent factors are usually …………………………… e.g.

Density-dependent limiting factors

Internal factors:Act within a species

External factors:Act between species

Limited breeding areas?

Predation

Disease

Limited food supply

Think: how do predator-prey relationships control the population size of both the predator and the prey?

How do limited breeding areas control the population size and leads to a better gene pool?

Density-dependent limiting factors

Internal factors:Act within a species

External factors:Act between species

Limited breeding areas

Limited food supply

Predation

Disease

Explain how predator-prey relationships control the population size of both the predator and the prey.

Explain how limited breeding areas controls the population size and leads to a better gene pool.

1. What are density dependent factors?2. What are density independent factors?3. What are internal and external factors?How do density-dependent and density-independent factors, and internal and external factors, regulate populations?