natural selection
1. Organisms
Organisms are all living things — plants, animals, humans, insects, even tiny bacteria.Every organism has traits like color, height, speed, beak size, fur color, etc.
2. Genes
Genes are the instructions inside an organism that decide its traits.You get your genes from your parents.Different genes create different versions of traits.
Examples:
Gene for dark fur
Gene for long neck
Gene for fast running
3. Variations
Variations are the differences between organisms of the same species.They exist because genes are not exactly the same in everyone.
Examples:
Some rabbits run faster
Some plants grow taller
Some beetles are darker
Some birds have longer beaks
Variations are important because they give nature “options.”
4. Natural Selection
Natural selection chooses which variations are better for survival in a certain environment.
Steps:
Organisms are all different (variations).
These differences come from genes.
Some variations help an organism survive better.
Those organisms survive longer and have more babies.
The helpful traits spread to future generations.
How ALL the things you gave me connect
Here is the full chain:
Genes → Variations → Organisms → Natural Selection → Survival
Genes create traits.
Differences in genes create variations.
Organisms with useful variations survive better.
Natural selection chooses those organisms.
Over time, the species changes and becomes better adapted.
Example with ALL the things included
Birds living on an island
Organisms: a group of birds.
Genes: some birds have genes for longer beaks, some have genes for shorter beaks.
Variations: beak length is different in each bird.
Natural selection: during a drought, only deep flowers have food. Birds with long beaks can reach it. They survive and have babies.Result: more long-beaked birds in the next generation.
Natural Selection
Happens naturally.
Nature chooses which traits help organisms survive.
Organisms with useful traits live longer and have more babies.
Takes many generations.
Example:Fast deer escape predators → more fast deer born.
Artificial Selection (Selective Breeding)
Happens because humans choose traits.
Humans select animals/plants with desired qualities.
Much faster than natural selection.
Example:Humans breed cows that give more milk.
Key Difference
Natural selection = nature chooses.Artificial selection = humans choose