Topic 5: Evolution Flashcards
Evolution
Change over time; change in the frequency (how often they appear) of selected genes within a population of organisms
Organisms tend to become more BLANK as they evolve through time
complex
What types of genes will increase in number as time goes on?
Genes with high adaptive value: these allow an organism to survive. They will pass from one generation to another
Evolution happens faster if…
The environment is changing
Evolution occurs as a result of…
Natural selection
Who proposed the theory of natural selection in 1859?
Charles Darwin
Natural Selection
If an organism has genes with adaptive value, they reproduce, passing the genes to the next generation. This causes the gene to become more common in the population. In a changing environment, favorable genes accumulate rapidly changing the appearance or behaviors of the populations
What may happen if a species doesn’t adapt/evolve in a changing environment?
They may go extinct
4 steps of natural selection
- Overproduction
- Competition
- Variation
- Selection and Reproduction
Overproduction
too many offspring are created. They can’t all survive because of limited resources in the environment.
Competition
Because species share common niches they will compete for food, space, mates, etc.
Variation
Sexual reproduction creates new combinations of genes
Mutations
change the DNA/gene slightly
Why are individuals of a population different?
They contain different genetic information because of sexual reproduction and mutations
Selection & Reproduction
The genes that are not adapted to the environment are selected against (die).
