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So we should now have a good grasp of where the variation we see comes from and how to predict the probability of a specific phenotype showing up. SO what drives the change in a population - the change that happens over time = Evolution. So how does that work?
Step 1 : So by now we know what a gene is and what an allele is - but we don't all have the same alleles as each other (we'd all be clones).
This whole collection of all the alleles in all the genes in the whole population is what we call the Gene Pool.
The human genome project established that us humans individually have between 20,000 - 25,000 genes = all the different combinations of these genes is our Genetic Diversity.
How often a certain allele turns up in the gene pool is the Allele Frequency (measured as a decimal, fraction or percentage). Allele frequency is an indication of genetic biodiversity.
Want to read more - https://www.khanacademy.org/science/biology/her/heredity-and-genetics/a/allele-frequency-the-gene-pool
Or watch this .... or do both (Learn)
Mission 1 : Your turn - read and complete the work on butterflies in your garden. (Learn)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Step 2 : Evolution and Darwin. This is quite a big step - Google - Charles Darwin and see what turns up = people today are still trying to get to grips with his ideas and disputing them and ..... so we'll chunk it ....
Step 2(a) : In the previous step the video clip and article mentions a thing called microevolution - we'll start with that = this is just the changes in allele frequency from one generation to the next. It will also introduce some of the ways allele frequency can change that we'll look at later. You look different from your parents - right ....
Let have this explained to us using allele frequencies. (Learn)
Step 2(b) : Now there are several mechanisms mentioned in this clip - these also apply to what Darwin was talking about which is Macroevolution = how organisms change over time.
But the mechanisms mentioned play a part in what Darwin called Natural selection.
Often this is described as "Survival of the Fittest" = not those that are simply cardiovascularly fit - but those that are the best fit for the environment that they live in.
Here it is explained to us. (Learn)
Mission 2 : Using what you now know plus what you can read in your workbook complete the questions on evolution and Darwin. (Learn)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Step 3 : So the main mechanism behind evolution is natural selection - so what is it and how does it work.
We have seen that via meiosis a lot of random genetic shuffling happens = a lot of random different looking offspring. Some of these will be better suited to survive others won't = those that survive pass on their genetics.
Ever had a "frog" in your throat ..... (Learn)
Mission 3 : How is your personal evolution going? Will you be selected? read and complete the questions on natural selection - mechanisms for evolution. (Learn)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Step 4 : So nature is "choosing" the ones that survive = the individuals that get to pass on their genes. What if we were all the same = no variation - and the environment changed? Why is biodiversity a measure of environmental "health"
Have a look as this is explained to us (Learn)
Mission 4 : How diverse is you knowledge of this - use the information above and read and complete the questions on how important variation is. (Learn)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Step 5(a) : By now you should have met somewhere sometime a thing called "The Bell Shaped curve" or a graph of "Normal Distribution" See below. (Learn)
Step 5(b) : Due to natural selection some phenotypes will always be more common - shortest, slowest, etc. So the "Normal curve" can get shifted due to this selection. There are 3 main types of shift ....
Stabilising = middle peak gets higher - as there are fewer extremes.
Directional = one extreme is undesirable - peak shifts towards other extreme.
Disruptive = extremes are more desirable than the middle - 2 peaks form.
May be easier to see in action .... (Learn)
Mission 5 : So where are you on the curve? Read and complete the work on types of selection in your workbook. (Learn)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Step 6 : In the clip above it mentioned the Peppered Moth from England - this was an example of both natural selection/evolution and pollution issues.
Watch and see what happened. (Learn)
Mission 6 : Using what you now know read and complete the work on the peppered moth in your work book. (Learn)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Step 7 : What happens when nature isn't in charge? When us humans choose which individuals get to reproduce? If its not natural selection then it is artificial selection - often called selective breeding.
How do you think we got Chihuahua's? Have a look. (Learn)
Mission 7 : What would happen if we let natural selection back in charge with Chihuahua's? You have ago at the questions on artificial selection in your work books. (Learn)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Step 8 : So far we've been working with the genes all ready in the gene pool - nature choosing the fittest.
What happens when we introduce a new gene = a mutation. What kind of mutation is most likely to be passed on via natural selection? (Silent, Harmful, Beneficial)
Where does it need to happen to be passed on? (Somatic or Gametic)
What are these terms? Have look the clips will help translate the new words. (Learn)
Mission 8 : Mutation - mechanisms for evolution - These are examples of longish answer questions that you'll get in the end of year exam. You'll need to use the specific example given and use the "science" you've learned to elaborate on how it all happens. (Learn)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Step 9 : Here is an example of directional selection and mutation happening - maybe in your house?
First watch the story behind the poison and the "super" rats (Learn)
Mission 9 : Using your new knowledge - here is some more exam question practice for you - once you've answered it ..... let me know how to best get rid of the rats in my hayshed - they're huge! (Learn)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Step 10 : Natural selection, artificial selection and mutation are not the only ways the allele frequency in a population can change. We can also get alleles leaving the population = individuals or groups leave - emigration. Or if new individual or groups move in AND interbreed with the existing population = contribute their alleles - immigration. The effects of migration can be big or small depending on the size of the population the alleles either leave or arrive into.
Here is a reminder of all that we have been talking about - but pay attention to the gene flow (or migration) section. (Learn)
Mission 10 : Okay your turn to investigate the effects of gene flow in Huhu beetles, by completing the exercise in your workbooks - remember the effects are more noticeable in small populations. (Learn)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Step 11 : When allele frequencies change due to chance events (not due to natural or artificial selection) we have Genetic Drift. It is far more noticeable in smaller populations.
2 major genetic drift events that we can study the effects of are the Founder Effect (small founding population) and the Bottleneck effect (sudden decline in population size).
Its easier to see these effects modeled rather than just read about them = watch. (Learn)
Mission 11 : After you've dusted off and played with your Lego ..... Read and complete the workbook sections on Genetic Drift, The founder Effect and The Bottleneck Effect. (Learn)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Challenge 1 : Modelling founder effect and bottleneck effects. Here is something you can do at home using Jellybeans, M and M's, Skittles (as suggested) or any other coloured lollies. Try out the exercises - don't eat any till you are done!! (Learn) (Create) (Share)
Mission 12 : Writing practice - possibly not as much fun as the above exercise - but super important to prepare for longer answer questions that you'll get in the end of year exams. Use the word list to complete the first Takahe question = then use that as help for the questions on Tuatara and Possum. (Learn) (Create) (Share)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Mission 13 : At the end of this section of your workbook you'll find (maybe) a puzzle page or two, a review planning page then a practice copy of the end of topic test. Complete these pages plus don't forget the definition page found at the start of the topic = you'll be ready for the test. (Learn)
Included here is a power point that reviews a lot of the information covered in this section .... plus extra to stretch your thinking. (Learn)
Population Genetics.pptGenetic Change review questions - you should have completed these by now = we'll go over the answers together. This should give you an idea of where you are at with your understanding of Genetic Change = let you know what you need to do the get ready for the practice exam at the end of the whole section on Genetic variation and change.
Final Mission : At the end of this topic there is also a practice exam that puts problems from all the 3 topics (Sources of genetic variation, Predicting inheritance and Genetic change) together in the form of the type of exam you'll be sitting at the end of the year. (we'll use for a trial run later in the year for the school practice exams) Do a bit more revision and give it a go. (Learn) (Share)
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