Transcript 7th grade ch. 6 sec. 1

Darwin’s Theory
Ch. 6
Section 1
Learning Target
• I can describe important observations
Darwin made on his voyage and explain
how natural selection leads to evolution.
Charles Darwin
• Darwin was 22 years old when he set sail on
the British ship HMS Beagle in 1831.
• A naturalist on the ship. (someone who
studies the natural world).
• Observed many types of plants and animals
and wondered why they were so different
from the plants and animals in England.
• Led to the theory of Evolution by Natural
Selection.
Darwin’s Observations
• Included…
• Diversity of living things, remains of
ancient organisms, and characteristics
of organisms on the Galapagos Islands.
Diversity and Fossils
• Darwin Noticed that animals were
diverse and that they adapted to the
environment in which they lived in.
• Fossil- preserved remains or traces of
an organism that lived in the past.
Galapagos Organisms
• Many similarities were found between the
Galapagos Organisms and the South
American Organisms. (plants and animals)
• There are differences too.
• Ex. Galapagos iguanas have longer claws
than South American.
> This is so they can grip on the slippery rocks
on the cost.
Adaptations
• Finches beaks varied between islands.
• Some had narrow beaks for eating
insects
• Others had wide beaks for eating
seeds.
• Adaptation: trait that helps an organism
survive and reproduce.
Evolution
• When animals arrived on the Galapagos
Islands they had to adapt to new
conditions and environment.
• The species gradually changed over
many generations.
Natural Selection
• Darwin’s Book “the Origin of Species”
proposed that evolution occurs by
means of natural selection.
• Natural Selection: process by which
individuals that are better adapted to
their environment are more likely to
survive and reproduce than other
members of the same species.
Natural Selection with turtles
• Overproduction: Turtles lay many eggs, not
all of the young survive.
• Variation: each turtle has slightly different
traits.
• Competition: turtles compete with one
another. A faster turtle may escape a
predator.
• Selection: variation such as speed make
some turtles better able to survive in their
environment.
• Survival and Reproduction: only few turtles
Learning Target
• I can describe important observations
Darwin made and explain how natural
selection leads to evolution.