Changes in beaks of finches on Daphne Major 5.2 Natural Selection Understanding: Natural Selection can only occur if there is variation amongst members of the same species Mutation, meiosis and sexual reproduction cause variation between individuals in a species Adaptations are characteristics that make an individual suited to its environment and way of life Species tend to produce more offspring than the environment can support Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring Individuals that reproduce pass on characteristics to their offspring Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species Applications Changes in beaks of finches on Daphne Major Evolution of antibiotic resistance in bacteria Nature of science: - Use theories to explain natural phenomena: the theory of evolution by natural selection can explain the development of antibiotic resistance in bacteria

Extension: Add on 3 more characteristics you can think of Prior learning… Use the words below to create a spectrum of inherited to environmental characteristics Extension: Add on 3 more characteristics you can think of INHERITED ENVIRONMENTAL Eye colour Tongue rolling Hair colour Accent Weight Scars Tattoos

Variation Organisms of the same species with different characteristics Variation can be affected by the environment or genes (or both!) Understanding: Natural Selection can only occur if there is variation amongst members of the same species

Asexual organisms only have genetic mutation to produce variation. Causes of variation Genetic mutations in DNA Meiosis: makes genetically different daughter cells Sexual reproduction: fusion of male and female gametes (different parents) Asexual organisms only have genetic mutation to produce variation. Slow evolution. Understanding: Mutation, meiosis and sexual reproduction cause variation between individuals in a species

Variation Experiment Collect data. Choose one example of variation. Draw a bar chart for your data. Graph paper, rulers and pencils at the front. Extension: change your height data into data suitable for a bar chart then plot a new graph. Understanding: Natural Selection can only occur if there is variation amongst members of the same species

To make continuous into discontinuous Create specific categories. i.e 140-145,146-150, etc starting with the lowest in the range and ending in the highest. Make a tally table: Draw a bar chart to now show this information as discontinuous. Height cm 130-135 136-140 141-145 etc Number of pupils II IIII

Dimples Gender Male or Female Tongue Roll √ if you can or X if you can’t Eye Colour Hair Colour, Is it natural or dyed? Dimples

Lobe None Thumbs curved or straight ? Hair on the middle bit of your fingers (just above knuckles) or none? Do your little fingers tips bend away from each other? Lobe None

Showing data

…this polar bear was bright pink? What would happen if… …this cactus didn’t have spikes? …this polar bear was bright pink?

Adaptations Species adapt to suit their environment Those that are not well adapted to their surroundings will die. Those that are well adapted will survive and reproduce Adaptations are passed on to the next generation This is survival of the fittest Understanding: Adaptations are characteristics that make an individual suited to its environment and way of life

Evolution by Natural Selection Understanding: Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring Individuals that reproduce pass on characteristics to their offspring Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species Evolution by Natural Selection Charles Darwin

They are all adults with different neck lengths! Once upon a time… Note: these are NOT baby giraffes They are all adults with different neck lengths! Giraffes once had variation in neck lengths

Giraffes compete to eat leaves from the trees and bushes

Over time the leaves start to thin out on the lower branches…

…to the point where the short-necked giraffes can no longer reach

The short-necked giraffes can no longer eat so die

The long-necked giraffes survive and reproduce to pass on their genes

The population of giraffes slowly change to all have long necks. They have adapted to their environment

Different selection pressures Darwin observed natural selection in the finches of the Galapagos Islands Different islands Different selection pressures Different beaks Applications Changes in beaks of finches on Daphne Major

Natural Selection: Finches Which beak will survive and reproduce? Each person will have a different shape ‘beak’ Each person has to pick up as many bits of food as possible in 1 min with their beak. All beaks go at the same time in your group: competition (you cannot bat food out of someone's beak!) Only one piece of food at a time. No scooping. Record the amount of food each beak picked up at the end of your minute (place into your beakers then count) Repeat the experiment 3x and find an average for each beak Sketch a bar chart to show and compare results. What do your results show? Which bird would most likely survive in this environment? Why? Applications Changes in beaks of finches on Daphne Major

Darwin's Finches: Natural Selection Conclusion: Which bird would survive? Why? Describe the experiment: Sketch graph of results: Extension: Describe the theory of Natural Selection by creating a comic strip (on the back of this page) Use the following key words: Natural selection Variation Competition Genes Survive Reproduce Adaptation Beak 1 2 3 Average

Natural Selection Comic Strip Describe the theory of Natural Selection by creating a comic strip Use the following key words: Natural selection Selection pressure Variation Competition Genes Generation Survive Reproduce Adaptation Applications Changes in beaks of finches on Daphne Major

Natural selection - Giraffe

Explain how natural selection leads to evolution Exam Question Explain how natural selection leads to evolution 6 marks

6 marks variation in a population; example of an environmental condition/selection pressure; some are better adapted than others to the environment; these tend to survive to reproduce themselves; characteristics are inherited; so the new generation has these characteristics too; this leads to changes in the population as a whole; these changes constitute evolution (by natural selection);

Overproduction Huge variations in breeding rates between species Hornbill: 1 offspring every 3 years Coconut palm: 60 coconuts per year Overall trend that organisms produce more offspring than an environment can support Competition for resources = not all survive and reproduce Understanding: Species tend to produce more offspring than the environment can support

Antibiotics Chemicals that inhibit the growth of microorganisms Block processes that occur in prokaryotes (but not eukaryotes) Do not cause harm to human cells Cannot treat viral diseases as they lack a metabolism (viruses only reproduce inside other cells)

Antibiotic Resistance

A natural population of bacteria has some that are susceptible and some that are more resistant

You start taking an antibiotic…

And the susceptible (weak) bacteria die first

You keep taking the antibiotic, more bacteria die

Until eventually only the most resistant bacteria are left

You stop taking the antibiotic

The more resistant bacteria reproduce and are likely to mutate

The more resistant bacteria reproduce and are likely to mutate

Now there are lots of more resistant bacteria

If I take the antibiotic again, what happens?

Nothing! All the bacteria are resistant!

Antibiotic Resistance The danger posed by growing resistance to antibiotics should be ranked along with terrorism on a list of threats nations. Sally Davies – England Government’s chief medical officer

Antibiotic Resistance When were antibiotics first introduced? Give examples of antibiotic resistant bacteria What makes them resistant to antibiotics? Why is that a problem? Applications Evolution of antibiotic resistance in bacteria Nature of science: - Use theories to explain natural phenomena: the theory of evolution by natural selection can explain the development of antibiotic resistance in bacteria

Exam Question Explain how natural selection can lead to evolution using antibiotic resistance in bacteria as an example. 9 marks

9 marks members of a population of the same species show variation; some organisms are more likely to survive due to selective advantage / survival of the fittest; some organisms have a reproductive advantage; these variations may be genetically controlled/heritable; these genes are most likely to be passed on to offspring; this can change the characteristic of the population; bacteria can normally be killed with antibiotics; antibiotics impose a selection pressure; if a few bacteria have natural resistance to the antibiotic they will survive; if the resistance is heritable they will pass it on to their offspring; they will reproduce/evolve to form bacterial colonies resistant to the antibiotic; example of organism selected by use of antibiotic; (e.g. MRSA bacteria / resistant TB bacteria)