evolution A process in which something passes by degrees to a different stage, such as a
living organism turning into a more advanced or mature organism; the change of the
inherited traits of a group of organisms over many generations.
evolution by natural selection The changes in the inherited traits of a population from
one generation to the next; due to a process where organisms that are best suited to
their environments have greater survival and reproductive success.
Galápagos Islands AgroupofislandsinthePacificoffSouthAmerica; ownedbyEcuador;
known for unusual animal life. Many scientists, including Charles Darwin made many
discoveries that led to the theory of evolution by natural selection while studying the
plants and animals on these islands.
inherited traits Features that are passed from one generation to the next.
natural selection Results when some organisms have traits that make them better suited
to live in a certain environment than others; they are more likely to survive, reproduce
and pass their traits on to future generations than those without the special traits.
species A group of individuals that are genetically related and can breed to produce fertile
young.
trait A feature or characteristic of an organism. For example, your height, hair color, and
eye shape are physical traits.
Points to Consider
- Evolution by natural selection is supported by extensive scientific evidence. What do
you think this evidence consists of?
7.2 Lesson 7.2: Evidence of Evolution
Lesson Objectives
- Understand that the scientific theory of biological evolution is based on extensive phys-
ical evidence and testing. This includes:- differences between fossils in different layers of rock
- the age of rocks and fossils