Evolution Survival of the fittest! Year 10 Biology
Lesson 2Natural Selection Role play your Darwin Vs. Lamarck Accounts of the evolution of Mosquitos -In paris and as a whole class! • 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 ideas • Answered practice questions on Natural Selection
Role Play Work in pairs to allocate a role (Darwin or Lamarck) to each person. Role play your Darwin Vs. Lamarck accounts of the evolution of Mosquitos
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.
Natural Selection • - INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE. • A.K.A. “SURVIVAL OF THE FITTEST” Summary of Darwin’s Theory There is variation in a population Those that are better suited to their environment, survive over others to reproduce These characteristics are passed down to the offspring
T-P-S • Why do you think that over time differences occur amongst a species that have been geographically separated?
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 lengths • 2. What is the selecting factor; food source on tall trees • 3. Who will survive to pass on their genes: Giraffes with long necks that can reach their food source. Summary of Darwin’s Theory There is variation in a population Those that are better suited to their environment, survive over others to reproduce These characteristics are passed down to the offspring
The 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 possible • Include an explanation of the origin of the first black moth & what happened to all the light coloured moths.
Approaching 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 Darwin’s Theory There is variation in a population Those that are better suited to their environment, survive over others to reproduce These characteristics are passed down to the offspring
Natural Selection: Practice Q 1 & 2. • 1. What is amain difference between Lamark’s theory and Darwin’s 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. Predation • B. Climate • C. Reproduction • D. Infection by pathogens
Natural 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, 4 • B. 3, 1, 4, 2 • C. 2, 3, 1, 4 • D. 1, 2, 4, 3
Natural Selection: Practice Q 4. • Streptococcus pneumonia is a type of bacteria that causes pneumonia in humans. This bacteria sometimes shows resistance to antibiotics • A. 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 marks • C. Natural Selection is also known as “Survival of the Fittest”. • Discuss the reasoning behind this term • 2 marks • Total 7 marks
Artificial Selection • Occurs 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 source • Pig 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?
Reflection • T-P-S • What are the three key pieces of information to include when answering a question about natural selection?