Darwin and Evolution UNIT 6. EVOLUTION THE PROCESS BY WHICH SPECIES CHANGE OVER TIME THEORY: Broad...
-
Upload
arthur-burns -
Category
Documents
-
view
217 -
download
0
Transcript of Darwin and Evolution UNIT 6. EVOLUTION THE PROCESS BY WHICH SPECIES CHANGE OVER TIME THEORY: Broad...
Darwin and EvolutionUNIT 6
EVOLUTION
THE PROCESS BY WHICH SPECIES CHANGE OVER TIME
THEORY: Broad explanation that has been scientifically tested and supported
• James HuttonJames Hutton -1785-Proposed that the Earth is millions of years old.
• Many land formations took millions of years to form.
• Known as the founder of modern geology.
History 2121
• Thomas Malthus -1798-• Proposed that populations outgrew
their food supplies, causing competition between organisms and a struggle for one species to survive against another
• This "struggle for existence" drives population change.
HistoryHistory 2222
Jean-Baptiste Lamark -18091809-
• Believed that all life forms evolved and that the driving force of evolution was the inheritance of acquired acquired characteristicscharacteristics.
• He believed that organisms changed due to the demands of their environment.
HistoryHistory 2323
What we What we understaunderstand now:nd now:
2424
•Charles Lyell -1830-proposed that plant and animal species had arisen, developed variations, and then became extinct over time. •He believed that every animal or plant, including humankind, was adapted to the niche in which it was created.
15.115.1
•He also believed that the Earth’s physical landscape changed over a long period of time.
the present is the key to
understanding the past
2525
•Alfred Russel Wallace -1858
• Emphasis was based on the idea of competition for resources as the main force in natural selection.
15.215.2
Best known for independently proposing a theory of natural selection which prompted Charles Darwin to publish on his own theory
2626
Charles Darwin• English naturalist who studied the diversity of life and
proposed a broad explanation for it
His experiences
provided him with
evidence of
evolution at work
• Charles Darwin -1859- Publishes “On the Origin of Species”
• Believed that Natural Natural SelectionSelection is the driving force for evolution.
2727
•From 1831 to 1836
Darwin served as a
naturalist aboard the
H.M.S. Beagle on a British
science expedition
around the world.
•In South America Darwin
found fossils of extinct
animals that were similar
to modern species.
•On the Galapagos
Islands in the Pacific
Ocean he noticed many
variations among plants
and animals of the same
general type as those in
South America.
CLIP
2929
Darwin’s Theory was based on…………..
• 1.) The voyage of the Beagle Observing different animal species from
around the world
• 2.) Studies of breeders – Dog breeders, cow breeders, etc.
Darwin’s Voyage
Beagle• Darwin took a trip on a ship called the Beagle
• Galapagos Islands in Pacific Ocean- collected finches – Studied the size and shape of the beaks
• Suggested that the Galapagos species descended from species that came from South America
Emu (Australia) Ostrich (Africa)
Rhea(S. America)
Darwin’s Observations
Darwin’s Theory of Evolution by Natural
Selection
Darwin’s Key Idea• Natural Selection
– Individuals that have traits that better suit the environment are more likely to survive and pass on their traits to offspring
Steps of Darwin’s Theory
• STEP ONE: Overproduction Every Population is capable of producing more
offspring that can possibly survive.
Steps of Darwin’s Theory
STEP TWO: Variation Individual members of a population are different
Steps of Darwin’s Theory
• STEP THREE: Selection– In a given environment, having
a trait can make individuals more likely to survive
Steps of Darwin’s Theory
• STEP FOUR: Adaptation over Time– Evolution takes time. Traits that improve
survival and reproduction will become more common over time
What Darwin Explained
• Presented a unifying explanation for data from multiple fields of science– Fossil record– Biogeography– Developmental biology– Anatomy– Biochemistry
Evaluating Darwin’s Ideas
• Darwin’s work had 3 major strengths:– Evidence– Mechanism for evolution (How it happened)– Recognition that variation is important
• However, he didn’t know much about genetics. – Lacked understanding of heredity
Charles Darwin
Darwin’s Ideas from ExperienceVoyage of the Beagle:
Steps of his Theory:
What did Darwin Explain:Fossil Record-
Biogeography-
Developmental Biology-
Anatomy-
Biochemistry-
Define:1.Artificial Selection
2.Natural Selection-
3.Adaptation-
Strengths of Darwin:Weaknesses of Darwin:
Charles Darwin
Darwin’s Ideas from ExperienceVoyage of the Beagle: •Noticed Galapagos plants & animals were similar, but not identical, to plants & animals in South America•Descent with modification
• Species had descended from species that came from South America and then modified over time
Steps of his Theory:
1.Overproduction- every population is capable of producing more offspring than can possibly survive2.Variation- variation exists within every population; inherited traits3.Selection- having a particular trait can make individuals more or less likely to survive and have successful offspring4.Adaptation- over time, those traits that improve survival and reproduction will become more commonWhat did Darwin Explain:
Fossil Record- comparing fossils and living things reveals a pattern of gradual change
Biogeography- similar environments shape the evolution of organisms in similar ways; geography can separate populations and the 2 groups may evolve in different patterns
Developmental Biology- compare development of species to look for similar patterns and structures that likely derive from a shared ancestor
Anatomy- homologous structure (ex. Vertebrate forelimbs)
Biochemistry- genetic changes occur over time in all population; compare DNA to show how genetically similar species are
Define:1.Artificial Selection- breeding animals or plants that have certain desired traits
1.Natural Selection- individuals that have traits that better suit their environment are more likely to survive and reproduce
1.Adaptation- trait that improves ability to survive and reproduce
Strengths of Darwin:
•Evidence of evolution- so much data!
•Mechanism for evolution (natural selection)- logical AND testable
•Variation- showed that is was everywhere and is important for understanding how population evolve
Weaknesses of Darwin:
•Inherited variation was crucial to Darwin’s theory of natural selection, but he did not have a clear mechanisms for inheritance. •Mendel’s findings about heredity solved this problem
Patterns of Natural Selection
1.Directional trait changes in 1 direction
2. Stabilizingtrait variation decreases
3. Disruptivetrait changes in 2 directions
Or is the whale descended from the Mosasaur?
Vestigial Structures
• Adjective describing something that is a vestige (remnant) or a primitive structure, and no longer believed to be important.
• Examples– Wings on flightless birds– Body hair on humans– Wisdom teeth in humans– Human Appendix
Darwin’s Theory was based on…………..
• 5.) Lyell– Geologist
– Rock layers show the earth is quite old
– Fossil record showed creatures who were now extinct
What Darwin’s Theory Explains
• Fossil Record
• Anatomy
• Biochemistry