Natural Selection
Snemalna Knjiga Besedilo
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- Hello, I'm here to explain Darwin’s theory of evolution by natural selection. The first thing I'll explain is Overproduction. Each species produces more offspring than can survive.
- For instance, a butterfly can lay up to 100 eggs on a single bush
- The next thing is Competition. Overpopulation causes members of the same species, as well as other species, to compete for limited resources like food, water and a place to live.
- Butterfly larvae (caterpillars) compete for host plants. For instance, the monarch caterpillar competes for only one species of plant called milkweed.
- Next is Variation. Variation is when organisms in population vary.
- For example, Butterflies of the same species have unique genotypes that will produce different phenotypes (observable characteristics like size, coloration, spots, wingspan).
- This green butterfly was born with a unique color which helps it blend in better to the environment.
- Here, this green Butterfly is showing Adaptation. This means that an individual may inherit a genetic trait that increases the chance of survival.
- Natural Selection, Organisms that inherit favorable traits are more likely to survive and produce offspring which will inherit the favorable trait.
- Look next to the dog house where the rees are. That is called natural selection. But the poor little spider did not survive because it was stuck on a pointy twig on the tree.
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- Lastly, I'm here to describe Speciation. A million years from now, I think the new species of butterflies would look like this. Favorable adaptations gradually accumulate, and unfavorable adaptations will disappear over many generations. After a very long time, a new species can form.
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