Transcript Natural Selection - Madeira City Schools

Natural Selection
Madeira Middle School
8th Grade Science
Learning Objective
• I can … describe the role of genetic and environmental factors
in the theory of evolution by natural selection.
• I can Identify who Charles Darwin is.
Charles Darwin
Carles Darwin
During HMS Beagle Journey
• Born in England in 1809
• Graduated from college
with a degree in
theology
• He then became a
naturalist – a scientist
who studies nature on
the British ship HMS
Beagle
• He observed and
collected many living
fossils
• He made his most
important observations
at the Galapagos Islands
in South America
• He kept a log that was
then latered published to
be the
The Voyage of the beagle.
Darwin
Evolution
• Evolution – process by which populations change over time
• Population – individuals of a species that live in an area at the
same time
• Species – group of closely related organisms that can mate to
produce fertile offspring
Darwin and his Studies
• Galapagos Islands
• Darwin studied plants and
animals
• Best known for his work
with finches and turtles
Collecting Birds
• Darwin collected Birds on the Galapagos Islands
• The birds differed slightly from the bird on the mainland
• The birds also on each island were different
• Darwin observed differences in beak size
• This had to do with their diets
• Page 361 in your book
Galapagos Turtles
Darwin’s Influence
• Artificial Selection – process by which humans select plants or
animals for breeding based on the desired traits
• Ex. – Horse Racing
• Artificial Selection shows that traits can change
• Traits can also spread through populations
Organisms Acquire Traits
• Jean – Baptiste Lamarck – organisms can acquire and pass on
traits they need to survive
• We know that acquired traits on not passed on through the
dna
• But the fact that species change, and the idea that an
organism’s traits help it survive, really shaped Darwin’s ideas
Earth Changes Over Time
• Law of Uniformitarianism supports that Earth has changed
over time
• Charles Lyell hypothesized that small changes in rock have
collected over hundreds of years
• Darwin said that if Earth was really old, then there would be
enough changes in life forms to add up.
The Struggle is Real
• Darwin did some research on how the environment could
influence which organisms can survive and which don’t
• All populations are affected by factors that affect population
growth
• Disease, predation, and competition for food
Natural Selection
• Natural Selection – process by which organisms that inherit
advantageous traits tend to reproduce more sucessfully than
other organisms do