Evolution Flashcards
(34 cards)
What is Evolution?
Evolution is the gradual change in species over a long time.
It explains how new species develop and how organisms become better adapted to their environment
What Causes Evolution?
- Variation
- Competition
- Natural Selection
Causes Evolution? 1. Variation
• Individuals in a species have different characteristics due to genetic variation (from sexual reproduction or mutation).
Causes Evolution? 2. Competition
Not all organisms survive — they compete for food, mates, and space.
Causes Evolution? 3. Natural Selection
• The best adapted individuals are more likely to survive and reproduce.
• They pass on their useful genes to their offspring.
• Over many generations, the species evolves.
Natural Selection
Natural selection is the process where the best adapted organisms survive and pass on their genes.
This idea was first suggested by Charles Darwin.
What is a Mutation?
• A mutation is a random change in DNA.
• Most mutations have no effect or are harmful.
• But occasionally, a mutation gives a survival advantage — and spreads by natural selection.
What Can Evolution Lead To?
- Adaptation
- New species (called speciation)
Evolution Lead To? 1. Adaptation
• A characteristic that helps an organism survive.
• Example: long neck in giraffes to reach high leaves.
Evolution Lead To? 2. New species (called speciation)
• If populations become separated (e.g. by geography), they may evolve differently until they become different species.
What is evolution?
A gradual change in a species over time.
What is natural selection?
When the best adapted organisms survive and pass on their genes.
What is a mutation?
A random change in DNA that may cause variation.
Who developed the theory of evolution?
Charles Darwin.
Why didn’t people believe Darwin at first?
He had no evidence from DNA, and it went against religious beliefs
What is adaptation?
A characteristic that helps an organism survive.
: How can a new species form?
Populations become isolated and evolve differently over time
How Does Evolution Happen?
- Variation exists in a species (from genes or mutations).
- Some individuals have features that help them survive better.
- These individuals are more likely to survive and reproduce.
- They pass on their useful genes to their offspring.
- Over time, these helpful characteristics become more common.
→ The species evolves.
Evidence for Evolution
Fossils
Antibiotic resistance
Fossils
Show gradual changes over time (e.g. horse ancestors)
Antibiotic resistance
Bacteria evolving to survive antibiotics
Mutation may give…
an advantage (e.g. camouflage).
Step 2 for How Evolution Happens
Mutation may give an advantage (e.g. camouflage).
Step 4 How Evolution Happens
They pass on the gene to offspring.
