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Hi there! I'm Studyfin, and today we will explore how natural selection shapes living things over time.
Natural selection is the process where organisms with helpful traits are more likely to survive and reproduce. It is important to know that natural selection changes whole populations over time, not individual living things. An individual cannot change its own genes during its lifetime to adapt.
For natural selection to happen, a population needs inherited variation, which means individuals have different genetic traits. There must also be overproduction of offspring, leading to a struggle for resources. Individuals with helpful traits survive and pass those traits to their babies.
Over many generations, natural selection can lead to speciation. This is the creation of a brand new species. This often happens when one group gets isolated from the rest, adapts to a new environment, and can no longer mate with the original group.
A population of brown mice lives in a grassy field. Over time, a mutation causes some mice to be born with green fur. Analyze how natural selection will affect this mouse population over several generations.
- Identify the inherited variation: The population now has two inherited fur colors, brown and green.
- Analyze the environmental pressure: Owls hunt the mice in the green grass. Brown mice stand out, while green mice blend in.
- Evaluate survival and reproduction: The green mice are hidden from predators, so they survive more often to pass on their green fur genes.
- Explain the population change: Over generations, the percentage of green mice in the population will increase, while brown mice will decrease.
- Conclusion: The population evolved to have mostly green fur because of natural selection, even though no single mouse changed its own color.
