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IQ2 How did Darwin explain this?
IQ2 How did Darwin explain this?
Natural Selection vs. 'Survival of the Fittest'
Natural Selection vs. 'Survival of the Fittest'
When Charles Darwin was developing the Theory of Evolution, he had to find a mechanism that drove evolution. Many other scientists, such as Jean-Baptiste Lamarck, had already described the change in species over time, but they didn't have explanations for how it occurred. Darwin and Alfred Russel Wallace independently came up with the idea of natural selection that gave that explanation.
Natural selection is the idea that species that inherit adaptations favourable for their environment will pass those adaptations to their offspring. Eventually, only individuals with those favourable adaptations will survive, which is how the species changes over time = evolves.
Someone not familiar with natural selection might take "fittest" to mean the best physical specimen of the species and that only those in the best shape and best health will survive in nature. That isn't always the case. Individuals that survive aren't always the strongest, fastest, or smartest. Darwin didn't mean it in those terms; he intended "fittest" to mean the members of the species best suited for the immediate environment, the basis of the idea of natural selection.
Since an individual needs the most favourable traits to survive in the environment, it follows that individuals with favourable adaptations will live long enough to pass their genes to their offspring. Those lacking the favourable traits—the "unfit"—most likely won't live as long to pass down their unfavourable traits to as many offspring, and eventually, those traits will be bred out of the population.
The unfavourable traits might take many generations to decline in numbers and longer to disappear from the gene pool. This is evident in humans with the genes of fatal diseases; their genes are still in the gene pool even though conditions are unfavourable for their survival.
Video (13 mins): How the owl developed eye spots - how natural selection really can occur!
Steps_in_Natural_Selection.pptxActivity 2.1 Evolution "fractured whispers"
Activity 2.1 Evolution "fractured whispers"
How can mutations cause new species?
The peppered moth, Biston betularia, has two colour patterns:
a light, speckled colour dd
a dark, speckled colour. DD, Dd
The colour is determined by one gene with the dark allele dominant to the light allele.
The peppered moths are active at night. They spend their days resting on the bark of trees, where they are preyed upon by birds. Moths rely on camouflage to hide from predators.
Evolution of a population occurred with peppered moths in the area of Manchester in England, from 1845 to 1890. Before the industrial revolution, the trunks of the trees in the forest around Manchester were light grey-green due to the presence of lichens. As the industrial revolution progressed, when large factories began to burn a lot of coal, the tree trunks became covered with black soot.
From 1835 on, the lichen began to die off the trees until it was all gone. With changes to industrialisation of the area from 1955, with soot exhaust being strongly regulated, the lichen began to re-grow on the trees.
Go to https://askabiologist.asu.edu/games-sims/peppered-moths-game/play.html.
Choose the light forest, move the bird's head (beak) over the moths to eat them. Write down the % after you eat the moths.
Choose the dark forest. Write down the % after you eat the moths.
What happened to the moth population after the Industrial Revolution?
What happened after the regulations for air pollution were tightened?
Photocopied and laminated frog and habitat cards. http://stileapp.com/go/habitatcards
Method:
Play in groups. If you don't have time to play the game in both environments, share results with a group that used a different environment to yours.
1. Collect 24 green frog cards and 24 yellow frog cards, and two habitat cards.
2. For one game, take a habitat card, 8 green frog cards and 8 yellow frog cards.
This is your initial population - "Year 0". Keep the remaining green and yellow frog cards nearby.
3. Shuffle the 16 cards of your initial population to mix up the green and yellow frogs.
4. Reproduction round: The frogs in your initial population will pair off and mate, having 1 offspring each.
* Take the frog cards from the top of the pack two at a time. These are mate pairings.
* If both frogs in a pair are green, add another green frog as their offspring.
* If both frogs in a pair are yellow, add another yellow frog as their offspring.
* If you have a green and yellow pair, throw the die. Both habitats: 1-3 green, 4-6 yellow.
* At the end of the round your population will have grown to 24 frogs.
5. Predation round: Now 8 frogs will be eaten by snakes.
* Throw the die 8 times to determine which colour frogs are eaten. Forest habitat: 1-4 yellow, 5-6 green; Swamp habitat: 1-4 green, 5-6 yellow.
* At the end of the round you will be back to 16 frogs. Record their colours.
6. Repeat steps 4 and 5 four more times.
* Label the results for each successive round, "Year 1", "Year 2", etc.
* If all the frogs of a colour are eaten before the end of a predation round, take out the number of frogs necessary to get back to 16 from the remaining colour to finish the round. That is the end of the game.
Task 2.6 Natural selection simulation
Task 2.6 Natural selection simulation
Visit https://sepuplhs.org/high/sgi/teachers/evolution_act11_sim.html and engage. First set up the three bird types, then choose environment. Predict their fittedness in the environment. Click "Next" each time to move on. Once you have your birds in their environment, click top to start and later to resume.
Follow your interest...
Follow your interest...
Visit https://learn.genetics.utah.edu/content/evolution/ and browse.
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