Evolution

EvolutionYear 10 Biology

Survival of the fittest!

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Lesson 2Natural Selection

Goal: To describe Natural Selection using examples and differentiate between natural selection and artificial selection

Glossary Words: Natural Selection, Artificial Selection

Success Criteria: Role played/ Shared ideasAnswered practice questions on Natural Selection

Role play your Darwin Vs. Lamarck Accounts of the evolution of Mosquitos -In paris and as a whole class!

Lamarck was totally wrong!2

Role PlayWork in pairs to allocate a role (Darwin or Lamarck) to each person.

Role play your Darwin Vs. Lamarck accounts of the evolution of Mosquitos

Lamarck was totally wrong!3

Natural Selection- INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE.A.K.A. SURVIVAL OF THE FITTEST

This process of evolution is known as NATURAL SELECTION and can be summarised in five points: 1 There is variation between organisms. 2 The numbers of natural populations remain fairly constant even though they reproduce in far greater numbers. 3 There is a struggle for survival. 4 Some variations help organisms survive. Organisms with less favourable characteristics die out. 5 The variations with survival value are passed on to the following generations, so over millions of years species become better adapted to their environment.

Today we will focus on

Charles Darwin (1809-1882) Sailed around the world 1831-1836 He Discovered The diversity of living species was far greater than anyone had previously known!! For example, when making observations on Galapagas islands, he saw that each island had its own type of tortoises and birds that were clearly different from other islands, geographic separation produced this due to natural selection, organisms that were better suited to their environment survived to reproduce It was these observations led him to develop the theory of evolution!!

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Natural Selection- INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE.A.K.A. SURVIVAL OF THE FITTEST

Summary of Darwins TheoryThere is variation in a populationThose that are better suited to their environment, survive over others to reproduceThese characteristics are passed down to the offspring

Today we will focus on 5T-P-SWhy do you think that over time differences occur amongst a species that have been geographically separated?

Separation Because different environments provide different pressures or challenges to survival

6Struggling to Survive

Approaching an exam question on Natural Selection:When answering ANY natural selection question, break it into 3 parts: (for example- Giraffes) 1. What is the variation; neck lengths2. What is the selecting factor; food source on tall trees3. Who will survive to pass on their genes: Giraffes with long necks that can reach their food source.Summary of Darwins TheoryThere is variation in a populationThose that are better suited to their environment, survive over others to reproduceThese characteristics are passed down to the offspring

As we have already seen, natural selection was the name given by Darwin to his explanation of the mechanism of evolution. He looked at the variety of plants and animals that existed on Earth. He noted that within a particular species there is variation between individuals that lead to some individuals being better adapted to their environment than others. For example, in a herd of antelope some might be good at running, some might be strong, and some might blend in better with their background environment and be less visible to predators. He thought that such individuals would be more likely to survive than others and so more likely to reproduce and pass on their advantageous qualities to their offspring. This explains why in a stable environment a species becomes better suited to the environment and why most of the organisms are so similar.

8The peppered MotHWhat happens when the environment changes?

Your Task: Use the information provided in the figure and in the previous slide to explain how you think the process of natural selection changed the appearance of peppered moths around manchester.

Detailed as possibleInclude an explanation of the origin of the first black moth & what happened to all the light coloured moths.In a stable environment, a population becomes better suited to its environment via natural selection and is said to be adapted to that environment. But what happens if the environment changes? Use the information in Figure 8.19 (page 194) to explain how you think the process of natural selection changed the appearance of peppered moths around Manchester. Make your explanation as detailed as possible. Try to include an explanation of the origin of the first black moth and what happened to all the light- coloured moths.

Survival of the fittest is more than having muscles, being tough or working out at the gym. Its about being better suited to a particular environment and having an increased chance of surviving long enough to be able to have offspring that will take your genes into the next generation.

9Approaching an exam question on Natural Selection:When answering ANY natural selection question, break it into 3 parts: (for example- Peppered Moths) 1. What is the variation (colour of the moths); 2. What is the selecting factor (birds);3. Who will survive to pass on their genes (black moths that can camouflage in industrial areas)

Summary of Darwins TheoryThere is variation in a populationThose that are better suited to their environment, survive over others to reproduceThese characteristics are passed down to the offspring

Natural Selection: Practice Q 1 & 2.1. What is a main difference between Lamarks theory and Darwins theory of evolution?

2. Many frog species inhabiting tropical rainforests have evolved green skin colour.It would be reasonable to conclude that the main selection pressure responsible for the evolution of green skin colour is:A. PredationB. ClimateC. ReproductionD. Infection by pathogens

Survival of the fittest is more than having muscles, being tough or working out at the gym. Its about being better suited to a particular environment and having an increased chance of surviving long enough to be able to have offspring that will take your genes into the next generation.

12Natural Selection: Practice Q 3.The following statement (NOT IN THE CORRECT ORDER) summarise the steps in natural selection.

1. Some individuals are better suited to a particular environment.2. Over time, there is an increase in particular characteristics in the population.3. There is variation within a population, some of which is genetic.4. Individuals better suited to the environment are more successful at survival and reproduction.5. The order of statements which best describe natural selection are:A. 1, 3, 2, 4B. 3, 1, 4, 2C. 2, 3, 1, 4D. 1, 2, 4, 3

Survival of the fittest is more than having muscles, being tough or working out at the gym. Its about being better suited to a particular environment and having an increased chance of surviving long enough to be able to have offspring that will take your genes into the next generation.

13Natural Selection: Practice Q 4.Streptococcus pneumonia is a type of bacteria that causes pneumonia in humans. This bacteria sometimes shows resistance to antibioticsA. How would have the antibiotic resistance first occurred in the population?1 marks The population of antibiotic resistant Streptococcus pneumonia has increased in the last 15 years. This is due to a process known as Natural Selection.B. Explain (step by step) how natural selection in the bacteria has occurred. 4 marksC. Natural Selection is also known as Survival of the Fittest.Discuss the reasoning behind this term2 marksTotal 7 marks

Survival of the fittest is more than having muscles, being tough or working out at the gym. Its about being better suited to a particular environment and having an increased chance of surviving long enough to be able to have offspring that will take your genes into the next generation.

14Artificial SelectionOccurs when humans artificially select individuals for breeding based on their possession of particular features in order to increase the chances that the offspring will have features that will suit our needs.

Examples:Plants to improve the quantity and quality of crops produced for a more dependable food sourcePig Farmers Select sows with the ability to produce large litters of piglets, grow quickly and convert feed into meat rather than into fat

T-P-S How do you think this is different from Natural Selection?

Darwin came to the conclusion that individual organ- isms with favourable characteristics are more likely to survive. Just as the dog breeder artificially selected particular individuals for breeding and discarded others, nature appeared to be selecting the features of a population that were well suited to their environment.

For thousands of years humans have made use of two very important factsthere is variation within a species, and offspring resemble their parents more than other members of the species. Knowing this, humans have selectively bred animals and plants for desired character- istics such as milk yield, fleece quality and grain size. Behavioural char- acteristics such as loyalty and a docile nature have been selected for in domesticated animals. This process is called artificial selection. As humans domesticated certain plants, they began a selective breeding process designed to improve the quality and quantity of the crops produced. This gave humans a more dependable food source than hunting and gathering could provide. Many of these plants are now so selectively bred that they probably could not survive in the wild. Modern agriculture is now in an uncomfortable balance. It must provide food for the billions of people on Earth but cultivated crops are very vulnerable to natural and human-caused disasters. In an attempt to protect the Earths food supply, many countries try to maintain seed banks of agriculturally important plants. Dairy farmers may wish to increase milk production. This can be done by collecting sperm from a bull that has been proven to produce offspring who are good milk-producers. By using the techniques of artificial insemination combined with fertility hormones and the use of surrogate mothers, hundreds of thousands of offspring can be pro- duced very quickly. In pig farming, breeders look for the ability of sows to produce large litters of piglets. This can be combined with choosing to breed pigs that grow quickly and convert feed into meat rather than into fat. Breeders

15ReflectionT-P-S

What are the three key pieces of information to include when answering a question about natural selection?

1. What is the variation; neck lengths2. What is the selecting factor; food source on tall trees3. Who will survive to pass on their genes: Giraffes with long necks that can reach their food source.

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