Evolution Notes
Charles Darwin
• Proposed the _____________________________________________
•
Evolution-gradual change in a _________________ through ____________________ over time
•
Theory of Evolution= ________________________________
•
Natural Selection- Organisms with traits well suited to an environment are more likely to
____________________ and _______________________ then organisms without these favorable traits.
•
Favorable traits will be passed onto the offspring so that they can survive
Evidence of Evolution
• Evolution occurs over millions of years and cannot be seen in one lifetime
• Scientists rely on evidence to support the Theory of Evolution
1.Adaptations
_____________________- structure of behavior that helps an organism better survive in its environment.
_______________- structural adaptation that enables one species to resemble another species.
_______________- structural adaptation that allows a species to blend in with its surroundings
____________________- changes in an organism’s metabolism that occurs quickly. Many
bacteria have become resistant to penicillin over the last 50 years
2. Fossil Record
Fossil-__________________________. Examples bones, dinosaur track, insects trapped in tree sap,
impressions of leaves, animals buried in tar or ice
- Give clues are to what _______________________ looked like
- Compare fossils to _______________ we know today
- Today’s species had to evolved from _____________________________
3. Comparative Anatomy
___________________________- body structures on different organisms that are similar in structure or
function and evolved from the same ancestor
___________________________- Body structures on different organisms that are similar in function but
did not evolve from the same ancestor.
___________________________- Body structure in an organism that no longer serves its original purpose
but was useful to the ancestor
Embryo- earliest stage of ______________________________ of both plant and animals
Human embryos and embryos of all other _______________________are very similar which suggests that
all vertebrates are related
Nearly all organisms have ______, _______, and many of the same _______________
The DNA of closely related organisms looks very similar
Natural Selection
 Occurs in populations over time not _____________________

_________________________- all the members of a species that live in an area

_________________________- all of the alleles of the population’s genes

______________________________- the frequency of alleles remains the same over generations

Populations in genetic equilibrium are not changing so they are not _________________

Anything that changes the genes in the population’s ___________________ will cause evolution to occur
What Causes Changes in the Gene Pool?
1. Mutations that occur by chance or by ______________________ and ______________________
2. _____________________: frequency of alleles are changed by random events in an isolated population
3. ___________________: the transport of genes by traveling individuals
4. _______________________: Individuals selecting mates with specific heritable traits (sexual selection)
5. Natural selection
3 Conditions for Natural Selection
 ____________________: more offspring are produced than can survive so organisms compete for survival

Natural _________________________ among individuals

Survival of the __________________
3 Types of Natural Selection
• __________________________: favors _______________ individuals in a population
•
__________________________: favors one of the _____________________ variations of a trait
•
_______________________________________: favors individuals with either extreme of a trait
Speciation
• Evolution of a new species that occurs when members of _____________________________ no longer
breed with each other to produce ____________________________
•
There are several reasons why similar populations no longer breed
- ____________________________: when a ______________________ (lava from volcanic
eruptions, sea level changes, etc.) divides a population
- _______________________________: occurs when organisms no longer breed with each other
to produce fertile offspring because of
- _____________________________________
- _____________________________________
- _____________________________________
How Fast Does Speciation Occur?
•
______________________________: idea that species originate through a gradual change of adaptations
(_________________________________)
•
_____________________________: idea that species originate in rapid bursts (_____________________)
with long periods of genetic equilibrium in between
Two Types of Evolution
•
____________________________ (adaptive radiation): species that once were similar become
increasingly different
•
____________________________: distantly related organisms evolve similar traits