Darwin’s Theory of Evolution. What is a scientific theory? A well substantiated explanation of...
-
Upload
malcolm-preston -
Category
Documents
-
view
216 -
download
1
Transcript of Darwin’s Theory of Evolution. What is a scientific theory? A well substantiated explanation of...
Darwin’s Theory of Evolution
What is a scientific theory?A well substantiated explanation
of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment.
The Puzzle of DiversityEvolution
◦Change over time◦Change in the inherited
characteristics of populations over successive generations.
Evolution how◦Mutations that result in better
chance for survival Traits are passed on to offspring
The puzzle of diversityCharles Darwin
◦Largest contributor to current understanding of evolution
◦Voyage of the H.M.S. Beagle Collected samples of life in different parts
of the world.
◦Galapagos Islands Patterns of diversity Fossils
Voyage of the Beagle
Galápagos Islands
Galápagos SpeciesTurtles
◦ Different length necks◦ Different shells◦ Work perfectly for the island on which they live
Galápagos SpeciesFinches
◦ Different beaks◦ Different colors◦ Traits correlate to
environment
Artificial Selection
If we can change a species through our choosing, why could nature not choose and change?
Humans choose which organisms survive and reproduce
Thomas Malthus 1798
• Human populations will out grow space and food supplies.
• Can you see this theory at play today?
Natural SelectionSome organisms in the fight for life are better equipped than others
Those best equipped will survive
Natural SelectionSome organisms in the fight for life are better equipped than others
Those best equipped will survive
Natural Selection
Principles on pg 422
Ideas That Shaped Darwin’s ThinkingInfluences on Darwin’s Thinking
◦James Hutton (1785) Geological forces shaped Earth. Earth millions of years old, not
thousands.
How are mountains formed?
Tectonic Plates
Are Scientific Discoveries Unique?Alfred Russel Wallace
Influences on Darwin◦Jean-Baptiste Lamarck (1809)
Living things have changed over time ~ all species descended from other species.
Species are adapted to their environment.
Jean-Baptiste LamarckOrganisms acquired or lost
certain traits during their lifetime. These traits could be passed on to their offspring.
3 parts to this idea…
Tendency Towards PerfectionAll organisms seek perfection
Acquire traits that help them flourish◦Birds’ desire to fly led to flight
Use and DisuseChange parts of body through
use and disuse
Bird tries to fly, wings develop over time◦Bird does not fly, wings fall off over
time
Tie an arm behind your back…
Inheritance of Acquired TraitsGained during an organism’s
lifetime◦Body builders, strong heart, obesity
Traits passed directly to offspring◦Since I run a lot, my child will see the
advantage
Epigenetics?
EvaluatingLamarck was wrong; so, what did
he contribute?
Laid the foundation for evolutionary theory
First to document that organisms adapt to their environment
Influences on Darwin◦Charles Lyell – Principle of Geology
Past events must be explained using processes that can be observed.
Slow process ~ These processes are still occurring!
◦Robert Frost once said, “In three words I can sum up everything I
know about life: it goes on.”
Stop, collaborate, and listen…Could one person come up with
and completely legitimize a theory on his/her own?
Could Darwin have drawn the picture of Evolution all by himself?◦Who were four of the main
contributing artists to his first proposal?
Darwin Presents His CasePublication of On the Origin of
Species◦Inherited Variation◦Artificial Selection◦Natural Selection
Struggle for existence Fitness and Adaptation Survival of the Fittest
Natural Selection Descent with modification Common descent
15-3: Darwin Presents His Case
Publication of On the Origin of Species◦Evidence
Fossil record Geographic distribution Homologous body structures Vestigial organs Similarities in Embryology
Strengths and Weaknesses of Evolution