PhET-Simulations-for-Biology/C3/Natural-Selection/English-timed

Time	Narration
00:01	Welcome to this tutorial on Natural Selection, an interactive PhET simulation.
00:08	In this tutorial, we will demonstrate Natural Selection, an interactive PhET simulation.
00:17	Here, I am using: Ubuntu Linux Operating System version 16.04,
00:26	Java version 1.8.0,
00:30	Firefox Web Browser version 60.0.2.
00:35	Learners should be familiar with biology and ecology.
00:41	Using this simulation, we will look at a population of rabbits for effects: Of mutations and selection factors,
00:52	Of environment, On pedigree.
00:55	Let us begin.
00:58	Mutations- Mutations are alterations in the nucleotide sequence of any genetic element. They are passed onto offspring.
01:11	Mutations may or may not change the observable traits or phenotype of an organism.
01:18	Inheritance of mutations can be dominant or recessive.
01:25	Use the given link to download the simulation.
01:30	I have already downloaded the Natural Selection simulation to my Downloads folder.
01:37	To open the jar file, open the terminal. At the terminal prompt, type: cd Downloads and press Enter.
01:48	Type: java space hyphen jar space natural-selection_en.jar. Press Enter.
02:03	File opens in the browser in 'html' format.
02:08	This is the interface for the Natural Selection simulation.
02:13	Observe the rabbit hopping in the simulation panel. Click the Pause button at the bottom of the interface.
02:22	Now we will explore the interface.
02:25	The interface has Simulation panel;
02:29	On the left side, Add Mutation, Edit Genes,
02:35	in the middle- Graph, Time until next generation progress bar,
02:42	Play/Pause button, Step button,
02:46	on the right side, Selection Factor, Environment, Chart.
02:54	Clicking on the Reset All button takes you back to the starting point.
02:59	Let us keep the default settings: None for Selection Factor Equator for Environment Population for Chart
03:11	Observe the Population versus Time graph.
03:15	It shows the number of rabbits along the y axis and time on the x axis.
03:22	Click Play button at the bottom of the interface.
03:26	In the graph, observe how the black line moves to the right.
03:31	Keep clicking on the Step button to move the simulation along faster.
03:37	If there are no rabbits left, you will see a Game Over pop-up box like this. The text will read “All of the bunnies died!”
03:48	Click on the Play Again button to resume the simulation.
03:53	Click on Add a Friend to add another rabbit to the simulation.
03:58	Click on Pause at the bottom of the interface.
04:03	Generations of Progeny
04:06	Observe the labels on the right and roman numerals on the left of each row. Generation P is shown in row I (one).
04:17	The F1 generation in row II (two) is made up of the progeny or children of generation P. And so on until row V (five).
04:30	We will allow the population to grow until F3. This would be three steps after the mating pair.
04:41	Click Play at the bottom of the interface.
04:45	Note how the progress bar is full when a new generation begins.
04:52	The progress bar starts moving to the left as a generation starts growing.
04:58	Click Pause button.
05:01	Click the second button at the top left corner of the graph to zoom out.
05:08	You can now see the height of the next step.
05:12	The black line shows the total number of rabbits in the graph.
05:17	Under Selection Factor, click the Food radio button.
05:22	Under Add Mutation, click the Long Teeth button.
05:27	A text-box, “Mutation coming” appears at the bottom of the simulation panel.
05:33	Note the yellow triangle with the lightning inside.
05:37	This indicates a mutation. You can see a picture of long teeth in the text-box.
05:45	Under Edit Genes, the rows next to the Teeth label have become active.
05:52	The radio buttons can now be clicked.
05:56	For each row, two options appear under the Dominant and Recessive columns.
06:03	To the left of each row are the pictures of long and short teeth.
06:09	Default selections are dominant mutation for long teeth and recessive for short teeth.
06:17	Observe the progress bar and the graph after the mutation has been added.
06:22	Let us allow the population to grow for another three generations after the mutation. Keep clicking on the Step button.
06:33	The interval between two narrow steps in the graph corresponds to a generation.
06:41	Click on the second Zoom Out button in the graph until you see the steps.
06:47	Observe how differently coloured lines appear in the graph after mutation and food selection.
06:56	Note that the timing of mutations and selection factors will affect population growth.
07:03	The legend below the graph gives the different colours and what they mean.
07:09	We introduced a dominant mutation for long teeth.
07:14	Let us look at the magenta line for long teeth, the olive line for short teeth.
07:23	Initially, the olive line is above the magenta line. The number of short-toothed rabbits is higher than that of the long-toothed rabbits.
07:36	Later, the magenta line is above the olive line.
07:41	The number of long-toothed rabbits has increased relative to the short-toothed ones.
07:49	This means that long teeth help rabbits survive by eating the available food.
07:57	Fur Mutation. Set up conditions to study effects of a fur mutation on survival of rabbits.
08:06	Keep brown fur as the dominant mutation and white fur as the recessive mutation.
08:13	Choose wolves as the selection factor.
08:17	Allow the population to grow for another 3 generations after the mutation.
08:25	Observe how the wolves move in and out, killing the rabbits.
08:31	Brown rabbits begin to appear after the mutation was introduced.
08:37	Note that we are still looking at effects of the dominant long teeth mutation besides brown fur.
08:46	Compare numbers of rabbits having white and brown fur in the graph and simulation panel.
08:55	Initially, there are more white rabbits than brown rabbits.
09:02	Later, the number of brown rabbits has increased relative to white ones.
09:10	At the equator, with wolves killing the rabbits, brown fur is an advantage for survival.
09:18	This strategy to blend with the environment is called camouflage.
09:24	What can you say about the numbers of long and short-toothed rabbits?
09:31	Sometimes a mutation changes the phenotype of all rabbits.
09:37	If so, the graph will not compare the mutation versus the wild type (unmutated) phenotypes.
09:45	Here, there are more long-toothed rabbits than short-toothed ones.
09:53	Tail Mutation Set up conditions to study effects of a tail mutation on survival of rabbits.
10:02	Keep long tail as the dominant mutation and short tail as the recessive mutation.
10:09	Choose wolves as the selection factor.
10:13	Allow the population to grow for another 3 generations after the mutation.
10:20	Keep clicking on the Step button to move the simulation along faster.
10:28	Click on the 2nd Zoom Out button.
10:31	Note the number of rabbits with brown fur, long teeth and short tails.
10:38	It is higher than that of rabbits with white fur, short teeth and long tails.
10:49	Brown fur and short tails help escape from wolves.
10:55	Long teeth help survival by making it easier to eat vegetation.
11:01	Under Chart, click Pedigree.
11:04	Note the text, “Click a Bunny” at the top.
11:08	Let us click on the rabbit at the left bottom corner of the simulation panel.
11:16	Observe how the selected rabbit is framed inside a blue rectangle.
11:22	The pedigree chart appears for the rabbit framed in the blue rectangle.
11:28	Click on the top right button in the Pedigree window.
11:33	The Pedigree window is separated and the Population chart appears behind it.
11:41	We can now resize the Pedigree window.
11:46	Note the color of the previous four generations of rabbits above the selected rabbit.
11:54	Red crosses on the rabbits indicate that they are dead.
11:59	The yellow triangle with the lightning symbol inside indicates a mutation.
12:06	It shows that that rabbit underwent a mutation so its genotype and phenotype changed.
12:14	Pedigree analysis allows study of inheritance of genes based on data about phenotypes.
12:23	Click repeatedly on the Step button. Rabbits can be seen all over the continents on the planet Earth.
12:33	Observe the caption, “Bunnies have taken over the world!”
12:38	These are the long-term effects of the simulation under these conditions.
12:44	Do refer to Additional material provided with this tutorial.
12:50	Let us summarize.
12:52	In this tutorial, we have demonstrated how to use the Natural Selection PhET simulation.
13:00	Using this simulation, we looked at a population of rabbits for effects: Of mutations and selection factors Of environment On pedigree
13:13	As an assignment, observe the rabbits: For effects of mutations and selection factors in Arctic environment
13:23	After switching mutations from dominant to recessive and vice versa. For changes in pedigree under different conditions
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13:59	This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching.
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14:21	This is Vidhya Iyer from IIT Bombay, signing off. Thank you for joining.

Contributors and Content Editors

Nancyvarkey, PoojaMoolya, Sandhya.np14