concept map natural selection
Storyboard Text
- Starting Population
- Overproduction
- Variation Competition
- The snail species, Fentonius laudermithi, lives on a brown, sandy beach. The snails are eaten by hungry birds that spot them from above.
- Adaptation
- More juvenile snails are born than can survive on the beach. There is not enough food or space for all of them to live. Some of the snails are always spotted by the birds and eaten.
- Differential Survival
- Not all of the snails are brown. Some snails are born with other colors. All of the snails on the beach are competing to stay hidden from the birds and not get eaten.
- Differential Reproduction
- The brightly colored snails really stand out against the brown, sandy beach. That makes them easy to spot from above. The brown snails match the color of their environment, making it easier for them to hide.
- Because their color is an adaptation on the beach, brown snails are better at avoiding the birds. Brown snails are eaten less often and survive longer.
- Only surviving snails get a chance to reproduce. Because most of those snails are brown, they pass on their brown color trait to their offspring. Therefore, a greater percentage of snails are brown in the next generation.
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