How Does Natural Selection Really Work? Objective: Understand How the Mechanism of.

How Does Natural Selection Really Work?

http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html

Objective: Understand How the Mechanism of Natural Selection Explains EvolutionKey Words: Genetic Variation, Competition, Overproduction, Survival of the Fit, Differential Reproduction, Accumulation of Traits

1. Arrange in order the 6 steps of Natural Selection: • Differential Reproduction, • Genetic Variation, • Survival of the Fit, • Accumulation of Traits, • Struggle for Survival, and • Overproduction

Accumulation of Traits

Differential Reproduction

Survival of the Fit

Struggle for Survival

Overproduction

Genetic Variation1.

2.

3.

4.

5.

6.



2. Which are the steps of the Natural Selection mechanism shown in the pictures?

Genetic Variation Struggle to Survivalor Survival of the Fit

Accumulation of traits Differential Reproduction

Overproduction



3. Cockroaches that are resistant to many common house-hold insecticides are more numerous than those that are killed by the same insecticides.

First, arrange in order the step of Natural Selection. Then match each steps with its description.

OrderStep of Natural

SelectionDescription

Struggle to Survive Cockroaches struggle to survive house-hold insecticides

Overproduction of Offspring

By reproduction, more organisms were produced that can survive

Genetic Variation

Those cockroaches with resistant-to- insecticides genes were better adapted to

survive in the house. This is known as survival of the fit

Differential ReproductionAfter many generations the favorable trait accumulated in the population. Eventually, organisms became resistant to the house-hold insecticide

Survival of the Fit

Not all of the cockroaches were identical. They had genetic variation. Some cockroaches had genes that made them resistant to house-hold insecticides and other did not have them

Accumulation of Traits

These cockroaches which survived, they reproduced and pass on the favorable variation – being able to survive the house-hold insecticide - to the next generation

Cockroaches that are resistant to many common house-hold insecticides are more numerous than those that are killed by the same insecticides. Explain how this can be possible.

1. GENETIC VARIATION

Not all of the cockroaches were identical. They had genetic variation. Some cockroaches had genes that made them resistant to house-hold insecticides and other did not have them.

2. OVERPRODUCTION OF OFFSPRING

By reproduction, more organisms were produced that can survive.

3. STRUGGLE TO SURVIVE

Cockroaches struggle to survive house-hold insecticides.

Objective: Understand How the Mechanism of Natural Selection Explains EvolutionKey Words: Genetic Variation, Competition, Overproduction, Survival of the Fit, Differential Reproduction

5. DIFFERENTIAL REPRODUCTION These cockroaches which survived, they reproduced and pass on the favorable variation – being able to survive the house-hold insecticide - to the next generation.

6. ACCUMULATION OF TRAITSAfter many generations the favorable trait accumulated in the population. Eventually, organisms became resistant to the house-hold insecticide.

4. SURVIVAL OF THE FIT

Those cockroaches with resistant-to- insecticides genes were better adapted to survive in the house. This is known as survival of the fit.

1. GENETIC VARIATION (genetic variation, mosquitoes, resistant, insecticide, genes)

Not all of the __________________ were identical. They had ________________. Some _____________ had ____________ that made them __________ to _________________ and other did not have them.

2. OVERPRODUCTION OF OFFSPRING (survive, reproduction)

By ___________________, more ______________ were produced that can ______________.

3. STRUGGLE TO SURVIVE (natural resources, struggle, insecticide)

Mosquitoes _____________to survive _______________________.

mosquitoes genetic variation

mosquitoes genes resistantinsecticides

survivereproduction

struggle insecticide

A population of mosquitoes is sprayed with a new insecticide. Most of the mosquitoes are killed, but a few survive. In the next generation, the spraying continues, but still more mosquitoes are immune to the insecticide. How could these results be explained?



mosquitos

4. SURVIVAL OF THE FIT (survival of the fit, adapted, insecticide, mosquitoes)

Those ______________ with resistant-to- _______________ genes were better _________ to survive____________. This is known as ____________________

5. DIFFERENTIAL REPRODUCTION (pass, reproduce, mosquitoes, being resistant to insecticide)

These ______________which survived, they ____________ and ________ on the favorable variation – _________________________ - to the next generation.

6. ACCUMULATION OF TRAITS (resistant, accumulated, insecticide, natural selection)

After many generations, the favorable trait _____________________ in the population. Eventually, organisms became ______________________ to the _________________.

This process is known as ______________________________

mosquitoes insecticideadapted insecticide survival of the fit

mosquitoes reproduce passbeing resistant to insecticide

accumulatedresistant

insecticide

Natural Selection





August’01. (69)A European species of rabbit was released on a ranch in Victoria, Australia. The species thrived and reproduced rapidly. The rabbits overgrazed the land, reducing the food supply for the sheep. The Myxoma sp. Virus was used to kill the rabbits. The first time this virus was applied, it killed 99.8% of the rabbits. When the rabbits became a problem again, the virus was applied a second time. This time, only 90% of the rabbits were killed. When the rabbits became a problem a third time, the virus was applied one again, and only 50% of the rabbits were killed. Today, this virus has little or no effect on this species of rabbit.

Explain what happened to the species of rabbit as a result of the use of this virus. You must include and circle the following terms in your answer: gene, adaptive value or adaptation or adapted, variation, survival of the fittest.

3. STRUGGLE TO SURVIVE Rabbits struggle to survive the Myxoma virus.

1. GENETIC VARIATIONNot all of the rabbits were identical. They had genetic variation. Some rabbits had genes that made them resistant to Myxoma virus and other did not have them.

2. OVERPRODUCTION OF OFFSPRINGBy reproduction, more rabbits were produced that can survive.

4. SURVIVAL OF THE FITTEST

Those rabbits with resistant-to-Myxoma-virus genes were better adapted to survive. This is known as survival of the fit



5. DIFFERENTIAL REPRODUCTION These rabbits which survived, they reproduce and pass on the favorable variation – being resistant to Myxoma virus- to the next generation

6. ACCUMULATION OF TRAITSAfter many generations the favorable trait – being resistant to Myxoma virus- accumulated in the population. Eventually, organisms became resistant to Myxoma virus.

This process is known as natural selection.

Learn how tuberculosis is transmitted and why the evolution of multi-drug resistant strains of TB in Russia affects us all

Objective: Understand Why Evolution Matters NowKey Words: Resistance, Tuberculosis, Antibiotics, Natural Selection

Jan’02 (68) In the past, a specific antibiotic was effective in killing a certain species of bacteria. Now, most members of this bacterial species are resistant to this antibiotic. Explain how this species of bacteria has become resistant. Your answer must include at least the concepts of: Overproduction variation natural selection adaptation to the environment.

3. STRUGGLE TO SURVIVE Bacteria struggle to survive antibiotics.

1. GENETIC VARIATIONNot all of the bacteria were identical. They had genetic variation. Some bacteria had genes that made them resistant to antibiotics and other did not have them.

2. OVERPRODUCTION OF OFFSPRINGBy reproduction, more bacteria were produced that can survive.


6. ACCUMULATION OF TRAITSAfter many generations, the favorable trait accumulates in the population. Eventually, bacteria became resistant to antibiotics

This processs is know as Natural Selection


Those bacteria with resistant-to- antibiotics genes were better adapted to survive. This is known as survival of the fit

5. DIFFERENTIAL REPRODUCTION These bacteria which survived, they reproduce and pass on the favorable variation – being resistant to antibiotics - to the next generation

Jan’02 (68) In the past, a specific antibiotic was effective in killing a certain species of bacteria. Now, most members of this bacterial species are resistant to this antibiotic. Explain how this species of bacteria has become resistant. Your answer must include at least the concepts of:

Overproduction variation natural selection adaptation to the environment.


Use the terms gene, variation, adaptation, and survival of the fittest to explain the evolution of resistance to a virus in gerbils.

Your explanation should be in accordance with the theory of natural selection.

3. STRUGGLE TO SURVIVE Natural resources were limited. Gerbils struggle to survive virus.

1. GENETIC VARIATIONNot all of the gerbils were identical. They had genetic variation. A few gerbils had genes that made them resistant to a virus and most of them did not have them.

2. OVERPRODUCTION OF OFFSPRINGBy reproduction, more gerbils were produced that can survive.


6. ACCUMULATION OF TRAITSAfter many generations, the favorable trait accumulates in the population. Eventually, gerbils became resistant to virus.

This is known as natural selection


Those gerbils with resistant-to- virus genes were better adapted to survive. This is known as survival of the fit

5. DIFFERENTIAL REPRODUCTION These gerbils which survived, they reproduce and pass on the favorable variation – to be resistant to virus - to the next generation

Use the terms gene, variation, adaptation, and survival of the fittest to explain the evolution of resistance to a virus in gerbils.

Your explanation should be in accordance with the theory of natural selection.


Some bacteria have become resistant to penicillin by producing an enzyme called penicillinase to destroy this antibiotic.

In an essay, explain one mechanism of these bacteria developing resistant.Include the terms variation, adaptation, natural selection, resistance, gene, and survival of the fittest.

3. STRUGGLE TO SURVIVE Bacteria struggle to survive penicillin.

1. GENETIC VARIATIONNot all of the bacteria were identical. They had genetic variation. Some bacteria had genes that made them resistant to penicillin and other did not have them.

2. OVERPRODUCTION OF OFFSPRINGBy reproduction, more organisms were produced that can survive.


6. ACCUMULATION OF TRAITS

After many generations, the favorable trait accumulates in the population. Eventually, bacteria became resistant to penicillin.

This process is known as Natural Selection.

5. DIFFERENTIAL REPRODUCTION

These bacteria which survived, they reproduce and pass on the favorable variation – being resistant to penicillin - to the next generation


Those bacteria with resistant-to- penicillin genes were better adapted to survive. This is known as survival of the fit

Some bacteria have become resistant to penicillin by producing an enzyme called penicillinase to destroy this antibiotic.

In an essay, explain one mechanism of these bacteria developing resistant.Include the terms variation, adaptation, natural selection, resistance, gene, and survival of the fittest.


Growers of fruit trees have always had problems with insects. Insects can cause visible damage to fruits, making them less appealing to consumers. As a result of this damage, much of the fruit cannot be sold. Insecticides have been useful fro the controlling theses insects, but in recent years, some insecticides have been much less effective. In same cases, insecticides do nothing to stop the insect attacks.

Provide a biological explanation for this loss of effectiveness of the insecticide. In your answer, be sure to:

a. Identify the original event that resulted in the evolution of insecticide resistance in some insects.__________________________________________________________________

b. Explain why the percentage of resistant insects in the population has increased. You must include and circle the following terms in your answer: gene, adaptive value or adaptation or adapted, variation, survival of the fittest.

6. A scientist discovered that in a large population of E.coli bacteria, a few were resistant to the antibiotic streptomycin. By adding streptomycin to the population, she soon obtained a large population that was resistant to streptomycin. A. Explain how this experiment supports the concept of evolution by natural selection. Your explanation should include the concepts of

Selective agentResistanceReproductionOffspring

b. Identify the chemical substance in the bacteria that provides the resistance to streptomycin and makes this resistance inheritable. C. The evolutionary changes described here occurred in a relatively short period of time rather than requiring millions of years. State one reason why it is possible for E.coli to evolves so rapidly.

E. Coli bacteria genetic variationgenes antibiotic streptomycin

reproduction survive

Natural resources struggle

___________________antibiotic streptomycin

Bacteria

bacteria

bacteria

antibiotic streptomycin

This process is known as ______________________________

reproduced passedbe resistant to antibiotic

accumulatesResistant to antibiotic streptomycin.

Natural selection

insecticideadapted survival of the fit

bacteria

bacteria

antibiotic

b. Identify the chemical substance in the bacteria that provides the resistance to streptomycin and makes this resistance inheritable.

C. The evolutionary changes described here occurred in a relatively short period of time rather than requiring millions of years. State one reason why it is possible for E.coli to evolves so rapidly

Jan’03 (70) Over the last 30 years, a part of the Hudson River known as Foundry Cove has been the site for many factories that have dumped toxic chemicals into the river. Some of these pollutants have accumulated in the mud at the bottom of the river. The polluted cove water contains many single-celled organisms and simple multi-cellular animals. Curiously, when the same species from nearby regions with non-polluted sediments are moved to the polluted cove water, they die.

Scientists hypothesized that the organisms living in the cove have evolved so that they are able to survive in polluted water. To test this hypothesis, biologists tried to duplicate the history of the cove in the laboratory.

They took a large number of one species of simple animal from a cove with unpolluted mud and placed them in a flask that contained polluted mud from Foundry Cove (diagram 1). Most of the animals died, but a few survived (diagram 2).

The scientists then bred the survivors with each other for several generations producing offspring that were descendants of the survivors. When placed in Foundry Cove, most of these descendants survived.

The diagrams below represent the steps in this investigation

On the diagram of the flask below, sketch the animals that would be present in flask 3 after several generations of breeding in the laboratory.

Explain how the simple animals of Foundry Cove adapted to the polluted water. Your answer must include an explanation of the role of three of the following in this process.

Environment genetic variation selectionreproductionsurvival of the fittest


DO NOW: Do you agree or disagree with the vignette? Explain.

How Does Natural Selection Really Work? Objective: Understand How the Mechanism of.

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